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FM 24-5
WAR DEPARTMENT
BASIC FIELD MANUAL
SIGNAL COMMUNICATION
FM 24-5
BASIC FIELD MANUAL
SIGNAL COMMUNICATION
Prepared under direction of the
Chief Signs] Officer
UNITED STATES
GOVERNMENT PRINTING OFFICE
WASHINGTON: 1939
For sale by the Superintendent ot Documents, Washingtoxi, D. C. - Price 45 cents
WAR DEPARTMENT,
Washington, November 1, 1939.
FM 24-5, Basic Held Manual, Signal Communication, is
published for the information and guidance of all concerned.
[A.G. 062.11 (7-17-39). I
By order op the Secretary of War:
G. C. MARSHALL,
Chief of Staff.
Official:
E. S. ADAMS,
Major General,
The Adjutant General.
TABLE OP CONTENTS
Chapter 1. General. Paragraphs Pages
Section I- General . 1-4 1-2
II. Organization 5-9 3—5
III. Command and staff duties of sig-
nal and communication officers. 10-12 5-7
Chapter 2. The Message Ckntxr.
Section I. General 13-24 . 9-20
II. Procedure for divisions and higher
units 25-30 20-29
III. Procedure in Headquarters below
the division 31-36 29-36
IV. Related procedures 37-42 37-39
V. Military cryptography 43-49 40-47
VI. Description and use of cipher de-
vice M-94 60-57 48-59
CHAPTER 3. MESSENGER COMMUNICATION.
Section I. General 58-60 60-61
II. Tratning of personnel 61-66 61-63
III. Employment ' 67-76 63-68
IV. Dropped messages 77-80 69
V. Pick-up of messages 81-85 70-73
Chapter 4. Pigeon Communication 86-89 74-77
Chapter 6. Radio Commtjnicattow.
Section I. General 90-97 81-86
II. Operating regulations 98-107 . 86-90
IU. Station, records 108-111 91-S4
IV. Tactical radio nets 112-118 94-97
V. Special procedures 119 98
Chapter 6. Visual Communication.
Section I. General 120-121 99
II. Lamps 122-129 101-107
III. Flags 130-135 108-110
IV. Pyrotechnics 136-141 110-113
V. Panels 142-155 114-122
VI. Airplanes . 156 124
Chapter 7. Sound Communication 157-160 125
Chapter 8. Wire Communication-.
Section I. General 161-183 126-145
II. Field wire line construction 184-206 145-193
III. Field telephones and centrals.— 207-225 195-224
IV. Field telegraph Sets and stations. 226-233 224-228
V. Maintenance of field wire sys-
tems 234--B45 228-243
Chapter 9. Signal Supply 246-265 245-248
Chapthh 10. Orders, Records, and Reports 258-262 219-257
Esaraples 258-284
index 285
in
PM 24-5
BASIC FIELD MANUAL
SIGNAL COMSIUinCATIOM"
(This pamphlet supersedes Basic Field Manual. Volume IV,
April 6, 1931 (including CI, January 2, 1937 and C2, January 3,
1938); TR 76-10, May 16, 1927; TE 160-5, June 28, 1929; TR 162-5.
April 20, 1926 (including CI, January 3, 192B, C2, January 2, 1929,
and C3, January 2, 1930).
CHAPTER 1
GENERAL
Paragraphs
Section I. General 1-4
II, Organization 5-e
m. Command, and staff duties of signal and com-
munication officers 10-12
Section I
GENERAL
B 1. General.' — Signal communication provides essential
channels through which a commander receives information
and directs the actions of his troops. He uses signal communi-
cation to receive reports of hostile dispositions and activities,
to receive reports of the progress and needs of subordinate
and neighboring friendly units, to send orders to subordinate
Units, to receive orders from superior units, and to send to
higher and adjacent units information necessary for the
coordinated action of the whole command.
■ 2, Object. — The object of this manual is to furnish basic
technical information governing signal communication essen-
tial to officers and enlisted men engaged in signal activities.
8 3. Scope. — The scope of this manual includes the methods
and technique relating to the installation, operation, main-
tenance of, and planning for signal communication with
special emphasis on such systems employed within the divi-
sion and smaller units. Some of this basic information is
also applicable to higher units.
■ 4. References. — a. Training publications. — For a complete
list of War Department training publications, see TR 1-10.
1
4
SIGNAL COMMUNICATION
(1) Technical Regulations. — Technical Regulations set
forth the information and instructions relative to specific
items of equipment. These regulations are guides for train-
ing personnel in the installation, operation, and maintenance
of the particular items of equipment. In general, those cov-
ering signal equipment fall within the TB 1200-series. (See
also par. 98b) ■
(2) Training Manuals. — TM 2260-5 is of interest to all
commanders whose headquarters are provided with a signal
or communication unit and of special interest to officers en-
gaged in signal communication.
(3) Field Manuals. — The following manuals contain perti-
nent matter relating to signal communication:
Field Service Regulations.
Staff Offleers' Meld Manual.
Signal Corps Field Manual,
b. Miscellaneous.. — (11 Army Regulations. — Instructions re-
lating to signal communication and Signal Corps activities
are found in the AR 105-series.
(2) Tables of Organization. — Tables of Organization pre-
scribe the organization of signal and communication units
and personnel with Qualifications thereof. They also show
for purposes of Information the items of transportation and
weapons authorized for the respective unit.
(3) Tables of Basic Allowances. — Tables of Basic Allow-
ances for the various arms and services contain a list of
items of signal equipment authorized for signal or communi-
cation units of the respective arm or service together with
the basis of issue for such items for both mobilization and
peace.
(4) Signal Corps General Catalog*. — The Signal Corps
General Catalog includes a descriptive section which con-
tains all items having signal corps type numbers arranged
by type number; a stock section which contains all items
in depot stocks arranged by stock number; and certain
appendixes, Appendix B of which is supplemental to Tables
of Basic Allowances, This catalog is essential to all signal
property and supply officers.
(5) Joint Army and. Nany Radiotelegraph and Radio-
telephone Procedure (par. 99b) . — The title is abbreviated as
JANP.
2
SIGNAL COMMUNICATION
6-6
Section II
ORGANIZATION
■ 5. Definitions, — a. Message.— The term "message" as
used herein includes all instructions, reports, orders, docu-
ments, photographs, maps, etc., in plain language or code,
transmitted by a means of signal communication. (See c
below.)
b. Agency of signal communication,, — The term "agency
of signal communication" embraces the personnel and equip-
ment necessary to operate message centers, signal intelli-
gence, signal supply, and messenger, pigeon, radio, visual,
sound, and wire communication.
c, Means of signal communication. — A "means of signal
communication" is an agency of signal communication ca-
pable of transmitting messages. The following agencies are
means of signal communication: messenger, pigeon, radio,
visual, sound, and wire communication.
<J. Command post. — The "command post" is the forward
echelon of a headquarters during combat. When the com-
mander leaves his command post for any purpose, he
normally keeps the command post informed as to where he
may be reached.
e. Axis of signal communication. — To secure continuity of
command and signal communication in combat when the
movement of command posts either forward or retrograde
Is contemplated, the probable successive locations of com-
mand posts should be selected in advance. The "axis of
signal communication" is designated by naming these suc-
cessive locations in the direction of movement.
■ 6. Signal and Communication Units. — In general, Tables
of Organization provide a signal or communication unit or
units to serve each headquarters from the battalion to
GHQ. The personnel of these units are either of the Signal
Corps or of the arm or service of the headquarters served.
Provision is made in Tables of Organization and Tables of
Basic Allowances for necessary personnel and equipment
to provide each headquarters with its needed signal
communication.
3
7-6
SIGNAL COMMUNICATION
■ 7. Sigh At Systems. — The signal system serving each unit
has a dual function. First, each tactical unit system is com-
plete within itself and functions to meet the need of the
unit commander; second, the system of each tactical unit
forms an integral part of the systems of superior units and
the whole functions to meet the need of the superior
commander.
■ B. Division Signal Agencies and Means. — a. Agencies. —
The following agencies' of signal communication may be
employed in the signal systems within the division:
(1) Message centers.
(2) Messenger communication.
(a) Airplane messenger.
(£0 Motor messenger.
(c) Motorcycle messenger,
(d> Bicycle messenger.
(e) Mounted (horse) messenger.
(/) Dismounted messenger (runner).
(3) Pigeon communication.
(4) Radio communication.
<a) Telegraph.
(b) Telephone.
(5) Visiial communication.
(a) Lamps.
(b) Flags.
(c) Panels.
fd't Pyrotechnics,
(e) Airplanes.
(6) Sound communication.
(7) Wire communication.
(a) Telephone.
(b) Telegraph.
(c) Telegraph printer.
(8) Signal supply.
b. Means. — The signal systems within the division gen-
erally employ the following means: wire, messenger, and
radio communication. Pigeon, visual, and sound communi-
cation are used for special purposes. In units where wire
and messenger communication are available, radio com-
4
SIGNAL COMMUNICATION
8-10
munication should be considered as an emergency means.
However, it is unwise to rely upon any one means to the
exclusion of others, because special circumstances may ren-
der that preferred means inoperative at a time when, signal
communication is urgently needed. It is for this reason
that signal and communication units are organized to permit
the simultaneous operation of several means which are
appropriate to the special need of the unit.
H 9. Teamwork. — Toi insure successful signal communica-
tion, the signal and communication troops must wort as a
team regardless of unit, arm, or service. There must exist a
spirit of mutual helpfulness and cooperation. Personnel of
adjacent units should take every suitable opportunity to
become personally acquainted, to understand the special
problems and conditions in neighboring units, and to offer
such assistance and cooperation in the installation, opera-
tion, and maintenance of signal communication as may be
practicable.
Section III
COMMAND AND STAFF DUTIES OF SIGNAL AND
COMMUNICATION OFFICERS
■ 10. Responsibility for Signal Communication. — a. Com-
mander. — Responsibility for signal communication is a
function of command. Each tactical commander is respon-
sible for the installation, operation, and maintenance of all
agencies of signal communication which form the signal
system of his own unit. For purposes of coordination and
technical control, he exercises supervision over the signal
systems of ail subordinate units of his command. For
example, an infantry regimental commander is responsible
for the installation, operation, and maintenance of his
infantry regimental signal system and for supervision over
the signal systems of his infantry battalions.
(1) The establishment and maintenance of signal com-
munication between subordinate and superior units are the
responsibility of the superior commander; between adjacent
units, as directed by their common superior.
5
10-11
SIGNAL COMMUHICATIOK
(2) A unit which supports another unit by fire is respon-
sible for the establishment and maintenance of signal com-
munication with the supported unit.
(3) In general, the responsibility for the establishment and
maintenance of signal communication with an attached unit
rests with the commander of the unit to which attached
unless the attached unit Is a fire supporting unit. (See (2)
above.) For example, an artillery unit attached to a front
line infantry or cavalry unit is responsible for the establish-
ment and maintenance of signal communication with the
command post of the unit to which attached.
b. Signal or eommmnication officer. — In general, each tac-
tical unit commander Is provided with a special staff officer
who is thoroughly trained in the tactics and technique of
signal communication. He is charged, under the direction of
the unit commander (or his G-3 or S-3), with the exercise
of tactical and technical supervision of signal communica-
tion for the entire command. This special staff officer in the
division headquarters is known as the signal officer. In
subordinate units he is known as the communication officer.
c. Channels of supervision. — The tactical and technical
supervision exercised by the signal or communication officer
over signal communication of subordinate units is subject
to the approval of his commander. The necessary super-
vision is exercised through the normal channels of command,
except that technical supervision over routine matters may
be exercised directly between the unit signal officers and
communication officers concerned.
■ 11. Staff and Command Functions. — a. The signal or
communication officer, as a member of the special staff
group, assists the tactical commander in exercising his com-
mand functions relative to signal communication and acts
as an adviser to the commander and other members of the
staff on all matters relating to signal communication. Under
instructions received from his commander, he acts as in-
spector and coordinator of the training and operations of
subordinate signal or communication units.
b. The signal officer commands, insofar as relates to train-
ing and tactical employment, all signal troops assigned to
8
SIGNAL COMMUNICATION
serve his headquarters. As a commander of troops, the
signal officer is responsible for the proper training and tac-
tical employment of his own signal unit.
c. These two functions of staff and command, although
vested in the same Individual, are separate and distinct in
that each, involves different responsibilities and duties and
the exercise of one should not be confused or permitted to
interfere with the exercise of the other. However, this dual
function of the signal officer has many advantages in facili-
tating the proper discharge of both his command and staff
duties.
■ 12. Detailed Duties. — a. Signal officer. — (1) During
mobilisation. — During mobilization the signal officer —
(a) Prepares requisitions for personnel to bring his unit to
authorized strength as prescribed by Tables of Organization.
(0) Inventories and inspects signal equipment, and requisi-
tions that which is necessary to bring the quantity on hand up
to that authorized by Tables of Basic Allowances for his unit
and for subordinate units.
(c) Prepares the training programs for signal communica-
tion troops of his unit and lower units under the general
policy laid down by his commander and by higher authority,
adapting it to meet local conditions and the time period al-
lowed for mobilization.
(d) Takes steps to secure and supply authorized training
equipment throughout the command.
(e) Organizes and supervises such troop schools for com-
munication specialists as may be authorized by his com-
mander or required by orders of higher authority,
(/) Prepares for the approval of the commander such
routine orders and signal operation instructions as may be
needed for the efficient training of the signal and communi-
cation personnel of the command.
(ff) Personally supervises the training of and secures the
training and organization equipment for the signal troops of
his unit.
(h) Recommends training for the signal units with the
staffs and the troops.
(2) During actual or simulated combat. — During actual or
simulated combat the signal officer — ■
7
12
SIGNAL COMMUNICATION
(a) Prepares or secures from higher authority such orders
and signal operation instructions as may be needed to insure
tactical and technical control of the signal system of his unit.
Insures the proper distribution of such orders and signal op-
eration instructions throughout his unit.
(b) Recommends the initial location of the command post
of his own unit, if this location has not been prescribed by
higher authority. Recommends the initial locations for the
command posts of the next subordinate units when prac-
ticable. When the necessity for the displacement of com-
mand posts during the operation can be foreseen, recom-
mends the axes of signal communication for the next sub-
ordinate units and for his own unit, when it has not been
prescribed by higher authority. Submits these recommen-
dations to the commander or to a designated staff officer, on
most staffs to the G-3.
(c) Prepares plans for the employment of the signal agen-
cies of his own and subordinate units so as to insure the most
efficient employment of these agencies within his own head-
quarters and the necessary coordination and technical con-
trol of the agencies of subordinate units,, subject to orders
received from higher authority. Submits these plans to his
commander or to the appropriate staff officer for approval.
(d) Prepares all signal orders based upon the approved
plan of signal communication, transmits these orders to the
proper issuing agency, checks on the issue of these orders,
and supervises their execution.
(e) Establishes and operates the signal system for which
his unit commander is directly responsible; supervises the
signal systems employed by subordinate units to discover
deficiencies; orders or recommends corrective action, and
thus secures coordination between systems during combat.
(/) Takes steps to procure and supervise the replacement
of signal, equipment and personnel of his own and subordinate
units.
o. Communication- officer- — The communication officer per-
forms duties similar to those for a signal officer with respect
to the signal communication troops of his own and subordi-
nate units when such duties are appropriate.
8
13-14
CHAPTER 2
THE MESSAGE CENTER
Paragraphs
Section1 I. General 13—24
H. Procedure for divisions and higher units!-"".. 25-30
III. Procedure In headquarters below the division.. 31-36
IV. Related procedures 37—42
V. Military cryptography 43-49
VI. Description and use of cipher device M-94 50-57
Section I
GENERAL
■ 13, Definitions. — a. Message center d — The message cen-
ter is the agency of the commander at each headquarters or
command post charged with the receipt, transmission, and
delivery of all messages except those indicated in paragraphs
16cland 356(1) (c).
&. Addressee. — An addressee is the person or office to which
a message is to be delivered. The term includes a repre-
sentative authorized by an addressee to receive his messages.
c. Message. — See paragraph 5a.
d. Writer. — The originator of a message is called the
writer,
e. Code. — Except as indicated in section V and in para-
graph 100, the word "code" and its derivatives is used in this
manual as a general term to include also cipher and Its
derivatives,
■ 14. PmtFosE. — a. The sole purpose of the message center
is to speed the transmission of messages. It seeks to
accomplish this purpose by —
(1) Providing a designated point to which messages and
messengers may be directed.
(2) Keeping informed of the current effectiveness of each
available means of signal communication.
9
14-15
SIGNAL COMMUNICATION
(3) Properly distributing message traffic to the available
effective means of signal communication.
(4) Eliminating unnecessary delays in transmission.
(5) Operating an efficient messenger service.
b. The message centers of division and higher units, are
operated by signal units. Message centers of subordinate
units are operated by communication units. Message cen-
ters are located at the command post and at the rear echelon
of the headquarters of large units. Advance message cen-
ters for the reception and relay of messages are employed
as a part of the signal system to facilitate signal com-
munication with advanced units or units operating on a
flank.
c. Advance message centers are established when required
to relay messages transmitted by different means of signal
communication or through different channels of the same
means. Information of their locations is always transmitted
to the troops. Advance message centers are frequently
employed as a part of the signal system to facilitate the
transmission of information and reports from front line
reconnaissance and security units. They are also employed
frequently in the reconnaissance operations of cavalry
divisions as collecting points for messages from several
reconnaissance detachments.
d. The message center is not organized or equipped to per-
form stenographic or clerical work pertaining to the head-
quarters which it serves. It is not equipped to prepare
copies of outgoing messages for multiple transmission, nor to
prepare additional copies of incoming messages for multiple
distribution. It will therefore not be used for these pur-
poses. (See par. 21.)
■ 15. CSjissification of Messages. — Messages are classified
according to —
a. Intelligibility of their language as clear or code messages
(sec. V) . — (1) A clear message is one in which the text of the
message conveys an intelligible meaning in a spoken lan-
guage.
(2) A code message is one in which the text of the mes-
sage conveys no intelligible meaning in any spoken language.
10
SIGNAL COMMUNICATION
15
b, Procedure used when transmitting electrically! — This
classification Tefers to the procedure employed in transmis-
sion of the message and in no way to the writing of the
message by the writer.
(1) Normal form. — The normal form message is ordinarily
used when transmitting messages electrically between divi-
sions or higher headquarters. The abbreviated form may be
used if desired, (See par. 31b.)
(2) Abbreviated form, — The abbreviated form message is
always used when transmitting messages by radio within the
division and between elements of the division and smaller
units. For messages sent by means other than radio the
normal form may be used if desired. (See par. 37e.)
e. Urgency with which handled, — Messages may be classi-
fied as urgent or priority by the writer. Messages trans-
mitted electrically in the normal form may carry any of the
four classifications given below as to urgency. Messages
transmitted in the abbreviated form will carry either the
urgent classification or no classification at all. In the latter
case they will be handled as routine messages.
(1) Urgent (O) . — Commanders must restrict the use of the
urgent classification to the most urgent messages; excessive
use will defeat its purpose. Urgent classification indicated by
symbol O is reserved for messages requiring the greatest
speed in handling. It is used only in combat or when real or
simulated combat is imminent to indicate that the message
conveys most urgent orders, information, or requests pertain-
ing to combat. It may also be used when reporting serious
damage or distress during peace or war. Urgent messages
will be sent immediately upon receipt, except when communi-
cation involving another urgent message is being carried on.
(2) Priority (P). — Priority classification, indicated by the
symbol P, is used for messages of less urgency than those
entitled to urgent classification but which warrant preced-
ence over routine messages in order to reach the addressee
in time for effective action. Priority messages will be trans-
mitted before such routine messages as may be waiting to be
sent, but transmission of a message will usually not be inter-
rupted to send a priority message.
11
15
SIGNAL COMMUNICATION
(3) Routine (no symbol). — Routine classification Is used
for messages which require no special precedence. The ma-
jority of the messages handled by the message center will
be routine messages. They are transmitted In the order in
which they are received.
(4) Deferred (NITE). — The deferred classification indi-
cated by the term NITE is used for those messages whose
delivery to the addressee may be delayed until the beginning
of office hours of the morning following the day on which
they are filed. (See JANP.)
d. Terminology employed in message center operation. —
(1) Outgoing messages. — Outgoing messages are those com-
ing to the message center from local sources for transmis-
sion to an office or individual served by another message
center. Under this same beading- fall those messages for
individuals of the headquarters or echelon served by the
message center and for those units not served by a message
center which are located beyond the normal operating dis-
tance of local messengers or at a considerable distance from
the message center.'
(2) Incoming messages. — Incoming messages are those
coming to the message center from an office or individual
not served by the message center for delivery within the
headquarters or echelon so served. Under this heading fall
those messages received from a distant member of the head-
quarters or echelon so served who is located beyond the
normal operating distance of local messengers.
(3) Relay messages. — Relay messages are those originat-
ing outside the headquarters or echelon served and sent to
the message center for delivery to an office or individual at
another headquarters or echelon.
(4) Local messages. — Local messages are those originating
at an echelon of a headquarters for delivery to another office
or individual at the same echelon. Such messages are not
handled by the message center.
e. Secrecy. — Messages are classified as secret by the writer
if their content so warrants. In simulated or actual tacti-
cal operations, all messages not classified as secret will be
regarded as confidential and need not be so marked. (See
AR. 380-5.)
12
SIGNAL COMMUNICATION
16-17
■ 16. Responsibility. — a. Outgoing messages. — The responsi-
bility of a message center begins when a message is re-
ceived by the message center and continues until the mes-
sage is receipted for by the addressee, another message cen-
ter, or a means of signal communication at another head-
quarters or echelon.
&. Incoming messages. — The. responsibility of a message
center begins with the receipt of the message by whatever
means of signal communication employed and continues
until receipted for by the addressee.
c. Relay messages. — The responsibility of the relaying
message center begins with the receipt of the message by
whatever means of signal communication employed and
continues until receipted for by the addressee, another mes-
sage center, or a means of signal communication at another
headquarters or echelon.
d. Other messages. — The message center is not responsible
for those messages which are —
(1) Transmitted directly by the writer to the addressee by
telephone or personal agency.
(2) Handled by the military or civil postal service.
(3) Local messages. (See par. 15d (4).)
■ 17. Flexibility op Organization. — a. Since the handling
of messages is an important function of command, the com-
mander of each unit is responsible for the adoption of meth-
ods whieh are satisfactory for his unit. Message centers will
operate with a varied number of men depending upon the
size of the unit, the magnitude of operations, the time of
day, and all other factors which affect the volume of traffic
to be expected during any given period. Flexibility in pro-
cedure and organization is therefore desirable and
authorized.
b. Situations peculiar to a particular headquarters organi-
zation or tactical operation may require special methods of
procedure. Commanders will be alert to recognize such situ-
ations and to adapt their methods to secure best results. A
standard procedure is desirable but it will not be considered
binding when departures therefrom will speed operation. In
adopting other methods, however, it should be borne in mind
181584°— 39 2
13
17-18
SIGNAL COMMUNICATION
that each message center must transact business with other
message centers. This will require a certain amount of
uniformity of procedure to prevent confusion. It should
also be borne in mind that personnel allotted the message
center is sufficient to handle only the minimum functions
incident to the handling of normal message traffic, and that
if operations in excess of these minimum functions are re-
quired, the necessary additional men must be provided by
the commander.
e. The methods of handling messages as set forth in this
chapter are intended to illustrate only two of several meth-
ods which may be employed successfully. Deviations there-
from are authorised if circumstances warrant.
■ 18. Training. — a. Objective. — The time required for all
clerical operations of the message center, including time
recording- and numbering of the message, enclosing and
preparation of the envelope if used, or preparation of a
delivery list should not exceed 20 seconds.
b. Maximum delay time in message centers. — No message
will be delayed In the message center on account of recording
operations longer than two minutes, exclusive of the time
required for coding or decoding. Commanders are responsi-
ble that sufficient personnel are available and properly
trained to accomplish this objective. If the volume of busi-
ness at any time exceeds the capacity of the message center
personnel to perform the normal recording operations within
this maximum delay time, the unit commander will be
promptly informed and additional personnel provided or the
normal operations abridged or eliminated.
C. Personnel. — For detailed instructions as to training of
messengers, see section II, chapter 3. The training of mes-
sage center and messenger personnel will emphasize — ■
(1) Military courtesy, with special reference to expres-
sions used in accepting and in delivering messages.
(2) Staff organization, particularly the organization and
personnel at local headquarters.
(3) Organization of the unit and the numerical designa-
tions of subordinate and superior units.
d. Conference with users of the system. — It must be real-
ized that commanders and staff officers do not always find
14
SIGNAL COMMUNICATION
18-19
time to keep up with regulations relating to use of the sig-
nal system. It will prove helpful to the entire unit if the
signal or communication officer finds opportunity in a staff
conference or otherwise to explain to the principal users of
the system such matters as —
(1) Handling of urgent, priority, routine, and deferred
messages and how the excessive use of urgent and priority
classifications will defeat the purpose for which they are
established.
(2) Handling secret and other messages.
(3) Value of writer's identification number in case future
reference to the message is anticipated between writer and
addressee.
(4) Schedules of messenger service, with the suggestion
that when practicable -outgoing messages be submitted to
meet these schedules.
(5) Advantage of the telegraph or telegraph printer over
the telephone for certain types of messages.
(6) Policy of the commander regarding the transmission
of radio messages in the clear. See paragraph 43 for basic
policy in this respect.
(7) Necessity for warning the message center of any unus-
ual demand for service which will be made upon it, such
as the distribution of held orders at a certain hour.
(8) Desirability for the writer to submit all messages in
duplicate.
(9) Directions for submission of messages for multiple dis-
tribution.
(10) Any other matters which reauire coordination.
■ 19. Informal Contact With Neighboring Message Cen-
ters. — Effective operation is facilitated by informal contact
between neighboring message centers on matters of mutual
interest. Such matters include reporting the delivery of an
Important message, notifying the other message center of
the reason for delay in securing an answer, warning the
neighboring message center that it will shortly receive or-
ders or other messages which will require special measures
for prompt handling, etc. Neighboring message centers
should thus work together as a team; each should assist the
other in meeting mutual problems and in answering likely
15
19-20
SIGNAL COMMUNICATION
inquiries. Each message center should welcome such assist-
ance from its neighbors.
■ 20. Principles of Operation. — a. Continuous service. —
During active operations, message center service is continuous
and is effected as follows:
(1) On the march. — Message centers may function during
the march to afford communication between columns, with-
in the column, and with aerial or ground reconnaissance
troops.
<2) Message center at each echelon. — A message center is
established at each echelon of the headquarters. (See par.
14b.) When an echelon moves, the message center opens at
the new location prior to or at the same time as the closing
of the message center at the former location.
b, Message center location. — (1) The message center and
the routes leading thereto should be well marked with ap-
propriate signs.
(2) On the march, the position of the message center in
column is made known to a!l concerned by designating its
position in the march order and by the use of pennants and
panels; the latter to mark the location from the air in order
that messages may be dropped in the immediate vicinity by
aircraft.
(3) The following are desirable physical features of the
message center:
(a> Quiet.
(b) Protection from rain and wind.
(c) Capability of being made lightproof at night and gas-
proof at any time.
(d) Accomodations for messengers, telephone stations, and
at large headquarters for telegraph, telegraph printer, and
radio stations as close as practicable to it.
(e) Convenience to staff sections and to incoming mes-
sengers,
c. Employment of means of signal communication. — In
coordinating the use of the various means of signal com-
munication, the message center employs the most suitable
and rapid means available for the transmission of any mes-
sage. To this end the message center will keep itself in-
16
SIGNAL COMMUNICATION
20
formed as to the availability of all means. The considera-
tions governing the means to be employed are:
(1) Messages to go only a very short distance should
habitually be sent by messenger.
(2) Maps, documents, photographs, and similar messages
must be sent by messenger unless equipment for facsimile
transmission is available.
(3) Short messages going a comparatively long distance
should be sent by some electrical means.
(4) Whenever possible, the telegraph or telegraph printer
should be used in preference to the telephone in order that
the latter may be kept open for direct communication by the
commander and his staff.
(5) Messages should be sent by pigeon only in case of the
failure of all other means of signal communication. The
instructions in paragraph 43 as to encoding radio messages
apply to pigeon messages also.
(6) Very long messages should usually be sent by mes-
senger.
(7) Messages transmitted by radio are subject to inter-
ception by an alert enemy. It therefore becomes essential
to encode all such messages as directed in paragraph 43.
Because of the delays incident to encoding and decoding and
because of possible interception, radio should be used only
when it is the sole means available or is clearly the most
suitable means.
<8) If the importance of the message so warrants, it may
be sent by two or more means subject to the restrictions
imposed by cryptographic security. (See AR 380-5.)
(9) Urgent and priority messages are sent by the most
Tapid means available. (See par. 15c.)
(10) Routine administrative reports must be transmitted
by means other than radio.
d. Forms and equipment. — Certain blank forms, stamps,
and other equipment are normally provided for convenience
and to save labor. Message center operation wilt however
not 6e made dependent upon blank forms or other equipment,
nor will the absence of such material be permitted to delay
messages in the message center.
17
21-22
SIGNAL COMMUNICATION
■ 21. Multiple Distribution.— When distribution of mimeo-
graphed or printed material to a number of addressees is
desired, all copies required for each addressee will be deliv-
ered to the message center wrapped, packaged, or otherwise
secured, and plainly marked with its destination. Each such
package, envelope, or container will be handled by the mes-
sage center as a single message and will be delivered by
messenger. One additional copy of the message should be
delivered to the message center.
■ 22. Messenger System. — For the employment of messen-
gers, see chapter 3.
a. Estimate of needs. — Since all local delivery and a large
portion of message traffic between message centers is handled
by messenger, an effective messenger system is indispensable.
It is therefore an important responsibility of the commander
to provide adequate personnel to meet the expected needs for
messengers and to provide for their means of transport. The
message center should be required to submit estimates of
messenger requirements supported by proposed schedules of
hours, routes, and distances. These estimates should show
the necessity for the detail of sufficient and suitable men.
b. Casualties. — War experience has shown that messengers
suffer heavy casualties and that when these casualties are
not promptly replaced or when insufficient men are detailed
to the messenger service, the messenger personnel is soon
brought to the limit of physical endurance. The unit com-
mander should therefore keep himself informed of the mes-
senger situation and should be prepared to detail additional
trained messengers whenever they are required.
c. Messenger' dispatcher . — The messenger dispatcher should,
be selected with care. He should be a forceful noncommis-
sioned officer and able to write rapidly; he should be men-
tally alert and have considerable endurance; and above all,
he should know how to handle his messengers with the
proper combination of understanding and firmness.
d. Organization. — It may be expected that the number of
messengers detailed will be the minimum estimated even
under the most favorable circumstances. It is vitally im-
portant therefore that this personnel be carefully selected
and well trained and that its transport be utilized at maxi-
18
SIGNAL COMMUNICATION
22-23
mum efficiency. As the requirements for messengers change
from day to day and even from hour to hour, the organiza-
tion must be flexible. This flexibility is enhanced if the
sleeping quarters of the messengers are in the immediate
vicinity of the message center. When practicable, messen-
gers should be organized into shifts and details to provide
24-hour service for —
(1) Local delivery.
(2) Scheduled messenger service to other message centers.
(3) Special messengers to handle urgent and priority mes-
sages and other special missions.
■ 23. Charts, Maps, and Diagrams. — The items given below,
particularly in divisions and higher headquarters, are some-
times found helpful in conducting the operations of the mes-
sage center. In order to be of value, it is essential that any
of the items used be kept up to date.
a. A display map to show the locations of headquarters of
the next superior and of the next subordinate units, the
scheduled messenger routes, and other information which
would be useful to messengers.
b. A corresponding diagram of the locations of the several
offices at the local headquarters, possibly showing the names
of the principal occupants of those offices.
c. A ready reference chart showing the various means of
signal communication established to the different units pre-
pared in substantially the following form and with pins
placed in appropriate spaces to indicate the means which
are established. (See par. 34a.)
Unit
Messenger
Telegraph
Telephone
Radio
IBTnf
mint
26 Ini _
7 FA
d. A list of officers on duty with the unit.
e. A duty chart of message center and messenger per-
sonnel.
19
24-26
SIGNAL COMMUNICATION
■ 24. Abbreviations. — In indicating the means by which
messages may be transmitted, the following abbreviations are
used:
Msg — Message
MsgCen — Message center
Msgr — Dismounted messenger (runner)
ApMsgr — Airplane messenger
Bel Msgr — Bicycle messenger
M Msgr — Motor messenger
Mtcl Msgr — Motorcycle messenger
Mtd Msgr — Mounted messenger
Scd Msgr — Scheduled messenger
SpMsgr — Special messenger
Pgn
— Pigeon
Bad
— Radio
Tg
— Telegraph
Tgp
— Telegraph printer
TP
— Telephone
Vis
—Visual
Section II
PROCEDURE FOR DIVISIONS AND HIGHER UNITS
■ 25. Organization. — a. In describing the procedure for
divisions and higher units, duties are outlined for message
center chief, messenger dispatcher, code clerk, messengers,
and operators of the several means of signal communication.
This division of duties is functional and is made for con-
venience in description. In small message centers during
periods of inactivity, one man may perform two or more
functions while in large and busy message centers two or
more men may be required for a single function.
p. The term "message center chief" is applied to the
senior specialist on. duty.
c. The term "operator" includes telegraph, telegraph
printer, and radio operators.
B 26. Equipment and Forms. — There is no guarantee that all
messages arriving at a message center for transmission will be
on standard forms and properly prepared. Nevertheless, the
20
SIGNAL COMMUNICATION
26
responsibility of the message center begins when the mes-
sage is presented to it by the writer, regardless of the manner
or form of presentation, and every effort will be made to
insure its rapid and accurate transmission to the addressee.
The following equipment and forms are helpful though the
procedure may be used without them:
a. Received stamp.— The received stamp indicates in per-
manent type the message center designation; in movable
type the month, date, and year and also provides for time
entry by clock operated stamp.
6. Serial number stamp. — This is an automatic numbering
stamp.
c. Field message book. — This book, 4% by 6 inches in size,
contains message blanks for all messages and special tissue
blanks for pigeon messages.
d. Message blank, US Army. — This blank is about 8 by 8
inches in size and is blank except for its heading and the
direction, "Submit message to message center in duplicate."
This blank is suitable for messages of usual length and is
convenient for typing and filing. If the form is not avail-
able or if the message is unusually long, any other type or
size of paper may be used.
e. Number sheet. — The following is an extract from W. D.,
S. C. Form No. 159. The complete form provides spaces for
100 messages. (See par. 34a.)
WAR DEPARTMENT
SIGNAL CORPS, U. S. ARMY
NUMBER SHEET
(Unit) (Date)
No.
RjSMAKKS
NO.
No,
Remarks
No.
la
77
Remarks
1
2
26
27
Remarks J
51
62
21
26
SIGNAL COWIMimiCATIOlT
/. Delivery lists. — (1) The following is an extract from
W. D., S. C. Form No. 160. The complete form, provides
spaces for seven, messages.
WAR DEPARTMENT
SIGNAL CORPS, TT. S. ARMY
LOCAL DELIVERY LIST
Time Dispatched
Time Ketuened
Message No.
Signature in Full
(2) The following is an extract from W. D., S. C. Form
No. 158, The complete form provides spaces for 19 mes-
sages.
WAR DEPARTMENT
SIGNAL CORPS, TJ. S. ARMY
ROUTE DELIVERY LIST
Time Dispatched
Time Returned
Message
No.
Sicnaturb in Full
Time Re-
ceived
(3) The above forms are used for securing receipts for
messages delivered by messenger. The one in CI) above is
most suitable for local messengers and the one in (2) above
for scheduled messengers.
g. Skeleton copy stamp. — This is a rubber stamp with the
word "SKELETON" in letters about 1 inch in height. This
stamp is used in stamping message blanks when preparing
skeleton copies. (See par. 27ff.)
h. Paper fastening machine, — This is a medium duty, spool
of wire type of machine.
22
SIGNAL COMMUNICATION
26-27
i. Message carrying bags. — These are bags for the use of
messengers.
■ 27, Handling Outgoing Messages. — The procedure pre-
scribed in this paragraph and paragraph 28 applies specifi-
cally to messages unclassified as to secrecy which are treated
as confidential. The procedure lor handling secret messages
differs somewhat and is described in paragraph 29. Outgo-
ing messages coming to the message center from a local
source may be handled by the separate specialists listed
below in the manner described:
a. Message center chief. — The message center chief —
(1) Receives the message in duplicate from the writer,
his representative, or a messenger.
(2) Immediately inspects the message for legibility and
proper address. He declines to accept illegible and Improp-
erly addressed messages and, if necessary, brings such mes-
sages immediately to the attention of the message center
officer.
(3) Writes the time of receipt on both copies of the mes-
sage or stamps the time of receipt on the back of both
copies with his received stamp.
(4) Writes or stamps the message center number with his
serial number stamp beginning a new series at midnight
each day.
(5) Checks the message center number off his number
sheet by drawing a diagonal line through the corresponding
number.
(6) (o.) If he decides that the message should go forward
by electrical means and transmission in the clear is normal
or authorized by the commander, he delivers the original of
the message at once to the operator and files the duplicate
copy in the live file. (See par. 34b.)
(b) If the message is to be transmitted in code, by radio,
or by other means, he passes the original of the message at
once to the code clerk and files the duplicate copy in the live
file. (See par. 20c (7).)
(c) If the message is to be sent in the clear by messenger,
he passes the original of the message at once to the messen-
ger dispatcher and files the duplicate copy in the live file.
23
27
SIGNAL COMMUNICATION
(7) Receives the signed delivery list from the messenger
dispatcher as soon as it has been returned by the messenger.
(8) Checks the transmitted messages off his number sheet
during lulls in traffic handling by drawing a second opposing
diagonal line through or encircling the corresponding num-
ber. Traffic will not be delayed to perform this operation.
(9) (a) Files the originals of electrically transmitted mes-
sages in the dead file when these are returned by the oper-
ator. These originals are used for reference. Removes the
duplicate copies from the live file and destroys them. (See
par. 34c.)
(o) Removes from the live file duplicate copies of messages
sent by messenger and places them and the signed delivery
lists in the dead file.
(10) Uses pigeonholes or envelopes for filing. For ready
reference these are labeled with the name of the unit whose
traffic they contain, for example, "From I Corps," "To I
Corps," "From 1st Div." "To Army," ,etc. Files are kept for all
units with which the message center does considerable busi-
ness. A file marked "From Miscellaneous" and "To Miscel-
laneous" is kept for all other business.
i>. Operator. — (1) Receives the original of the clear text
message from the message center chief or the original en-
coded message from the code clerk.
(2) Transmits the message and receives a receipt from
the distant operator.
(3) Services the message in his possession and when he no
longer needs it for verification, returns It to the message
center chief for file: (See a (9) (a) above.)
c. Code clerk. — (1) Receives the original of the message
to be encoded from the message center chief.
(2) Encodes it without making a duplicate copy of the
encoded message.
(3) Indicates pertinent data as to address, operating in-
structions, and urgency, if any, on the encoded message.
(4) Passes the encoded message either to the operator or,
in case of messenger transmission, to the messenger dis-
patcher.
(5) Files the original of the clear text message in his file.
24
SIGNAL COMMUNICATION
27
d. Messenger dispatcher (f below). — The messenger dis-
patcher, who is charged with the handling of messengers —
(1) Receives the original of a clear text message from the
message center chief or a code message from the code clerk.
(2) Normally prepares one copy only of a delivery list for
transmission by messenger. However, if there is danger of
the messenger becoming a casualty or if an unreliable mes-
senger must be employed, he prepares the delivery list in
duplicate. A good carbon copy must be made in these eases
and this copy is retained by the messenger dispatcher,
(3) Enters the message eenter number in the first column
of the delivery list.
(4) Stamps or writes the time dispatched in the proper
blank space of the delivery list just prior to the messenger's
departure.
(5) Hands the message and delivery list to the messenger
and gives him any instructions necessary.
(6) Stamps or writes the time returned in the proper
blank space of the signed delivery list when it is returned
by the messenger.
(7) Hands the completed delivery list to the message cen-
ter chief.
e. Messenger (.f below) . — The scheduled or special messen-
ger—
(1) Receives the message and delivery list from the mes-
senger dispatcher and proceeds to the distant message center
or to the addressee.
(2) Delivers the message and delivery list to the message
center chief of the distant message center or to the ad-
dressee who signs it and, in the case of the route delivery list,
enters the time of receipt in the last column.
(3) Receives the signed delivery list from the message
center chief or addressee and either returns to his own mes-
sage center or continues to other message centers or ad-
dressees on his route if he has additional deliveries to make.
(4) On his return, enters either his name, initials, or his
messenger number as required by local regulations, on the de-
livery list for identification.
(5) Hands the delivery list to the messenger dispatcher
of his own message center.
25
27-28
SIGNAL COMMUWICATIQN
/. Scheduled messenger service, — (1) Routine messages. —
For scheduled messenger service, the delivery list is handled
as follows:
(d) When a scheduled messenger has just departed on a
certain scheduled route and the next message for delivery
on that route reaches the messenger dispatcher's desk, the
latter enters the message center number in the first column
of a delivery list. He enters succeeding messages for that
route on successive lines as they arrive.
(&) when the time scheduled for the next messenger's
departure arrives, the messenger dispatcher enters or stamps
the time dispatched in the proper space, turns the delivery
list and messages over to the messenger, and gives him such
instructions as may be necessary.
(c) The messenger delivers the messages according to his
standing instructions supplemented by such special directions
as he may have received for the particular run. He secures
a signature for each message.
(2) Other messages. — Delivery of urgent and priority mes-
sages will not be held up for a scheduled messenger.
g. Skeleton copy of message. — Some messages will be sub-
mitted to the message center without a duplicate copy. If such
a message is to be transmitted by electrical means, the single
copy is all that is required. But if it is to be transmitted by
messenger, a skeleton copy is made for follow-up and this
copy is thereafter handled as a duplicate copy. The skeleton
copy is usually brief. For example, in case of a 100 -word
message relating to class I supplies, the skeleton copy might
be simply, "QM to Army QM Class I supplies." In case of a
bundle of maps it might be, "G-3 to G-3, 26 Div bundle
maps." A very brief description is all that is required for
identification. An urgent or priority message is not delayed
for the preparation of a skeleton copy. If a skeleton copy is
required, it is made as accurately as possible from memory
after the message has been dispatched and the notation
FROM MEMORY is added.
■ 28. Handling Incoming Messages. — Messages received at a
message center for delivery to local addressees may be han-
dled in the manner indicated below. Incoming messages are
not assigned message center numbers.
26
SIGNAL COMMUNICATION
a. Operator. — (1) Copies the message in duplicate.
<2) Services the message, entering time received under the
message.
(3) If the message Is in the clear, passes or delivers —
fa) Original to the messenger dispatcher for delivery to
the addressee.
(b) Duplicate copy to the message center chief when no
longer needed for verification.
(4) If the message is in code, passes or delivers —
(a) Original of the message to the code clerk.
<b) Duplicate copy of the message to the message center
chief when no longer needed for verification.
b. Message center chief. — (1) Receives and riles the dupli-
cate copies from operators referred to in a above.
(2) Receives the message from an incoming messenger,
signs the delivery list of the distant message center, returns
the delivery list to the messenger, and stamps the message or
its cover with his received stamp; hands the message di-
rectly to the messenger dispatcher or to the code clerk if in
code; after the message has been delivered, receives the
completed local delivery list from the messenger dispatcher
and files it in the dead file.
e. Code elerfc. — (1) Receives the original of the cade mes->
sage from the operator or from the message center chief if
received by messenger.
(2) Decodes the message, making an original only.
(3) Enters the operator's heading on the decoded message.
(4) Passes the message to the messenger dispatcher, files
the original of the code message in his file for reference, and
disposes of this file as directed by the unit signal or com-
munication officer,
d. Messenger dispatcher, — The messenger dispatcher re-
ceives an original of a clear text message directly from the
operator, a decoded message from the code clerk, or a mes-
sage transmitted by messenger from the message center
chief, and —
(1) Prepares a delivery list.
(2) Designates a messenger to deliver the message.
(3) Stamps or writes the time dispatched in the proper
space when the messenger is ready to depart.
27
28-29
SIGNAL COMMUNICATION
(4) Hands the message and delivery list to the messenger.
(5) Stamps or writes the time returned in the proper space
when the signed delivery list has been returned to him. by
the messenger.
(6> Hands the completed delivery list to the message cen-
ter chief.
(7) In handling urgent and priority messages and in order
to avoid delay in delivery, the messenger may be given a
blank delivery list and be instructed to request the addressee
to UJl In the message number as well as the signature, and in
ease of the route delivery list, the time of receipt.
e. Messenger, — (1) Receives the message and the delivery
list from the messenger dispatcher.
(2) Delivers the message and the delivery list to the ad-
dressee and obtains his signature, and in the case of the
route delivery list, the time received.
(3) Returns to the message center and enters his name,
initials, or his messenger number as required by local regula-
tions, on the delivery list for identification.
(4) Hands] the delivery list to the messenger dispatcher.
■ 29. Handling Secret Messages. — The handling of secret
messages is prescribed in detail in AR 380-5. The procedure
for handling secret messages in the message center differs
from the handling of nonsecret messages in the respects
mentioned below. In tactical operations when time permits,
secret messages will normally be carried by a staff officer or
special messenger operating as a direct agent of the trans-
mitting office. They may be transmitted by electrical or
other means available to the message center when the time of
transmission can be reduced thereby.
a. Outgoing messages, — The writer of an outgoing mes-
sage submits to the message center only a single copy of a
secret message. The message center chief stamps this message
with his time stamp and serial number stamp, makes the
notation "Secret" in the REMARKS column of his number
sheet, and passes the message to the code clerk. The code
cierk makes an original and one duplicate copy of the coded
message, these copies being henceforth handled in the same
manner as nonsecret messages. The original of the plain
28
SIGNAL COMMUNICATION
29-32
test message is then marked, "Sent in secret code" and is
returned to the writer. The original of the coded message
is passed to the transmitting agency and the duplicate code
copy is kept in the live file and final disposition made in the
same, manner as for duplicate copies of nonsecret messages.
b. Incoming messages, — An incoming secret message is
handled like a nonsecret message except that the single copy
secret code."
of the plain text is marked by the code clerk, "Received in
■ 30. Handling Relay* Messages. — a. The operator hands or
sends both the original and the duplicate copy to the message
center chief whether received in code or in clear. In case
the message is received from a messenger, only the original
is available.
b. The message Is then handled as an outgoing message.
It is not given a message number by the relaying message
center.
c. A message received in code is not decoded by the relay-
ing message center.
d. A copy of the message will be available in the message
center with the operator's service for follow-up if received or
transmitted by electrical means.
e. No copy of the message will be available in the message
center if received and transmitted by messenger. In this
case, the signed delivery list or message envelope is the only
record. If considered necessary, a skeleton copy may be
made for reference.
Section III
PROCEDURE IN HEADQUARTERS BELOW THE
DIVISION
E 31. General. — Simplicity and speed In handling message
traffic aie paramount considerations. If necessary to meet
local requirements, unit commanders are authorized to make
modifications in the procedure given in paragraph 35.
H 32. Organization. — a. In describing the procedure, duties
are outlined for message center chief, messenger dispatcher,
code clerk, messenger, and operators of the several means
of signal communication. This division of duties is func-
181584°— 39 3
29
32-34
SIGNAL COMMUNICATION
tionai and is made for convenience in description. For defi-
nitions of the terms "message center chief" and "operator"
see paragraph 25. For the classification of messages, see
paragraph 15.
b. In small message centers during slack periods, one man
may perform all the duties at the message center. For this
reason each member of the message center team must be
trained to perform all the duties incident to message center
operation. The message center personnel should be able to
operate as two teams In order to provide for continuous oper-
ation when the command post is moved.
c. If shortage of personnel requires it, the duties of the
code clerk may be delegated to the radio section. (See
par. 43.)
B 33, Forms and Equipment. — Message center procedure is not
dependent on forms. No equipment other than pencil, paper,
and the authorized codes and cipher devices is required.
Certain forms such as delivery lists, number sheets, field
message books, and message envelopes are, however, usually
provided for convenience and to save labor, (See par, 26.)
■ 34. Records. — The message center keeps only such tem-
porary records as are required to insure rapid and accurate
handling of message traffic, The following records are
usually kept:
a. Number sheet. — Message center numbers are assigned
to each outgoing message. (See par. 27a (4).) If desirable,
the chart referred to in paragraph 23c and the number sheet
referred to in paragraph 26e may be combined into a message
center log. An example of an extract of such a log is
shown below. Spaces for 100 numbers and additional units
may be conveniently provided on the form. If it is used, the
instructions in this chapter dealing with the number sheet
apply also to this form.
30
SIGNAL COMMUNICATION
MESSAGE CENTER LOG
34
1st FA
(Unit)
5-4-39
(Date)
Recobd ov Serviceability or Agencies
No.
EE-
MARES
No.
Re-
marks
■
TJjJITS TO
^Hrdi
NECTErj
BAD
TG
TP
In
Out
In
Out
111
Out
4th F, A.
Brig
WA
SSOA
SSOA
70SA
SiSA
1000A
71SA
SiSA
10QOA
SSOA
SSOA.
705A
BiSA
I0OOA
SSOA
1
2
3
i
6
6
r
8
9
10
Rod
Tg
Msgr
61
52
S3
U
55
56
57
58
59
00
700A
70SA
71SA
SOOA
70SA
SOOA
11
61
IstBn
SOOA
SISA
81SA
SOOA
SiSA
900A
12
62
1st F. A.
SOOA
910A
SWA
moA
13
83
14
C4
15
1(5
65
66
b. Live file. — The live file consists of a duplicate or skeleton
copy of each outgoing message which has been sent to a
signal agency for transmission but for which a receipt has
not yet been obtained.
c. Dead file. — The dead file consists of the duplicate or
skeleton copies of all receipted outgoing messages; receipted
delivery lists or message envelopes; and the receipted dupli-
cate clear text copies of all incoming messages received in
code by means other than messenger. The dead file is dis-
posed of daily or oftener as directed by the unit communica-
tion officer. Unless otherwise directed by the commander, it
is turned over to S-l at frequent intervals so that messages
may be included in the unit journal.
d. Code elerfcs file. — This file contains the original clear
copy of all outgoing messages seat in code and the original
copies of all incoming code messages. Caution: Clear and
code copies of the same message must never be filed together.
31
34-35
SIGNAL COMMUNICATION
The file is disposed of daily as directed by the unit com-
munication officer.
■ 35. Handling Messages (par. 17c) .—The following pro-
cedure may be used in handling messages at a message
center. The procedure indicated is intended to illustrate
only one of several methods which may be employed success-
fully.
a. Outgoing messages. — (1) Message center chief. — (a) Re-
ceives the message in duplicate from the writer or makes a
skeleton, copy in case only one copy is received.
(b) Enters on both the original and duplicate copies of
the message in the proper spaces at the top of the field
message blank, or in any convenient place if the regular
message form is not used, the following:
1. Time fileiL — The time the message was filed at the
message center.
2. Message center number. — The next unassigned mes-
sage center number.
3. How sent. — The means of signal communication
selected for transmission. (See par. 24.)
(c) Checks off the number assigned the message by draw-
ing a diagonal line through the number on the number
sheet.
(<J) Notes briefly, opposite the number assigned to the
message on the number sheet, such data pertaining to the
message as he considers necessary for reference.
(e) Hands or sends the original of the message to the
operator, messenger dispatcher, or code clerk if it is to be
encoded.
(/) Places the duplicate copy of the message in the live
file.
(g) Services the duplicate copy of the message when noti-
fied by the transmitting operator of the time of receipt by
the distant operator; or, in case the message was sent by
messenger, on the return of the signed delivery list or mes-
sage envelope. This servicing may consist of entering on the
face of the message the date, time of receipt, and the per-
sonal sign of the message center chief, all inclosed in a circle.
(ft) Places the serviced duplicate copy in the dead file fco-
32
SIGNAL COMMUNICATION
3S
gether with the signed delivery list or message envelope if
used.
(0 Indicates on the number sheet that receipt for the
message has been obtained. This may be done by drawing
an opposing, diagonal line through or encircling the as-
signed number on the number sheet.
(2) Code clerk. — (a) Receives the original of the message
from the message center chief.
<&) Prepares one encoded copy of the message for trans-
mission and enters on the top of the message such data as
appropriate and required by the means to be employed.
This will include the destination of the message, indicated by
either the unit designation of the addressee or the call sign
of the unit; operating instructions, if any; and the urgency
of the message, if indicated by the writer. If the message is
to be transmitted by messenger, the official designation of
the addressee and writer must be shown in clear either on
the message itself or on the message envelope if used.
(c) Hands or sends the completed code message to the
transmitting agency. If going by messenger, he hands it to
the messenger dispatcher, if there is one, otherwise he hands
it to the message center chief.
(<Z) Files the original clear copy of the message.
(e) Destroys all work sheets by burning.
(3) Messenger dispatcher. — (a) Receives the original of
the message from the message center chief or the code mes-
sage from the code clerk.
(b) Prepares one copy of a delivery list or message en-
velope and enters the time dispatched.
(c) Hands the message and delivery list, or the enveloped
message, to the messenger and gives him such special in-
structions as may be necessary. If the message is to be
sent by pigeon, he places it in the message holder, releases
the bird, and notifies the message center chief of the time of
release. If the message is to be sent by the airplane pick-up
method, he sends the message to the panel station. The
message center chief is notified of the time of pick-up.
(.d) Receives the signed delivery list or message envelope
from the messenger on his return.
33
35
SIGNAL COMMUNICATION
(e) Enters the time returned, and hands the signed deliv-
ery list or message envelope to the message center chief.
(4) Operator. — (a) Receives the message from the code
elerk, if encoded, or the message center chief, if it is to be
sent in clear.
(b) Transmits the message.
(c) Services the message after acknowledgement of receipt
by the distant operator.
(d) Notifies the message center chief without delay when
the message has been transmitted and informs him of the
time of receipt by the distant operator.
(e) Retains the transmitted copy of the message in his
file for verification. The file is disposed of as directed by
the unit communication officer.
b. Incoming messages. — (1) General. — (a) Incoming mes-
sages are not assigned message center numbers.
(i>) Operators and the code clerk, in the case of code mes-
sages, are responsible for local delivery. Local delivery lists
are not used, receipt being obtained on the duplicate copy
of the message as received or as decoded.
(e) Incoming special messengers deliver their messages to
addressees, obtaining receipt on their delivery list or on the
message envelope. No action is taken by the personnel of
the local message center other than to direct the incoming
messenger to the location of the addressee.
(d) Incoming scheduled messengers deliver their mes-
sages to the message center chief who signs for them and
effects delivery by local messenger. Obtaining local re-
ceipts is optional. The message center chief hands code
messages to the code clerk; the latter, after decoding, delivers
the message to the addressee.
(2) Operator. — (a) Copies and services the message in du-
plicate.
(b) If the message is received in the clear, delivers both
the original and the duplicate copy to the addressee and
obtains a receipt on the duplicate copy. The. receipted du-
plicate copy is handed to the message center chief when no
longer needed for verification.
34
SIGNAL COMMUNICATION
35
(e) If the message is received in code, hands or sends the
original to the code clerk and retains the duplicate copy in
his file for verification.
(3) Code cleric. — (a) Receives the original of the code mes-
sage from the operator or the message center chief, if
received by messenger.
(&) Decodes the message making an original and duplicate
clear copy,
(c) Delivers the original and duplicate clear copy directly
to the addressee and obtains a receipt on the duplicate copy.
id) Gives the receipted duplicate copy to the message
center chief.
(e) Files the original of the code message in his file for
verification.
(/) Destroys all work sheets by burning.
(4) Message center chief, — (a) Keeps informed as to the
locations of offices and individuals served by his message
center.
(b) Directs incoming special messengers to the person or
office sought.
(c) Signs for Incoming messages received from scheduled
messengers and arranges for their local delivery. In case
a message is received in code, he hands the code message to
the code clerk.
id) Arranges for local delivery by messenger in situations
where it is not practicable or convenient for operators or
the code clerk to deliver incoming messages directly to the
addressee.
(e) Files the signed duplicate copies of the messages he
receives from the operators and code clerk in the dead file.
c. Relay messages. — (1) The receiving agency hands or
sends both the original and the duplicate copy to the message
center chief whether received in code or in clear. In case
the message is received from a messenger, only the original
is available.
(2) The message is then handled as an outgoing message
(a above) except that it is not given a message center num-
ber. The TIME FILED and HOW SENT items at the top
of the message form are filled in under any corresponding
entries which may be already there.
35
35-36
SIGNAL COMMUNICATION
(3) A message received in code is not decoded by the
relaying message center.
(4) A copy of the message will be available in the message
center with the operator's service for follow up if received
or transmitted by electrical means.
(5) No copy of the message will be available in the mes-
sage center if received and transmitted by messenger. In
this ease, the signed delivery list, or message envelope, is
the record. If considered necessary, a skeleton copy may be
made for reference.
B 36. Messenger Service. — a. Scheduled. — (1) Scheduled
messenger service is established only when the locations
of command posts, establishments, etc., are fixed for a suffi-
cient length of time to Warrant its employment.
(2) Scheduled messengers always deliver their messages to
the message center of the addressee. Receipt for messages
is obtained on a delivery list.
(3) The signed delivery list is returned by the scheduled
messenger to his own messenger dispatcher or message center
chief.
b. Special. — (1) Special messengers should always be avail-
able. They are dispatched as needed.
(2) Special messengers dispatched to the headquarters of
divisions or higher units deliver their messages to the mes-
sage center of the unit concerned.
(3) Special messengers arriving at headquarters below the
division deliver their messages direct to the addressee., If
necessary, information as to the location of offices is secured
from the local message center.
(4) The signed delivery list or message envelope is returned
by the special messenger to his own messenger dispatcher
or message center chief.
c. Local. — In certain situations it may not be practicable,
particularly in higher units due to dispersion of command
post installations and. other factors, for the message center '
chief or the code clerk to hand messages direct to the trans-
mitting agency or for operators or the code clerk to deliver
their incoming messages direct to the addressee. In such
cases, local messengers must be available to provide for local
deliveries within the command post.
36
SIGNAL COMMUNICATION
37
Section IV
RELATED PROCEDURES
■ 37. Electrical Transmission of Messages. — a. General.—
(1) It is important that message center personnel have suf-
ficient knowledge of radio and telegraph procedure to en-
able them to prepare messages properly for transmission and
delivery when electrical means are used; b and c below are
based upon the current Joint Army and Navy Radiotelegraph
and Radiotelephone Procedure.
(2) The telephone is not considered a satisfactory means
for a message center tec use in transmitting message traffic
because it denies to more important use the circuits being
so employed. If a message cannot be sent by telegraph,
telegraph printer, radio, or messenger, the writer should be
notified so that he personally or one of his representatives
may communicate direct with the addressee by telephone.
The telephone in the message center, if installed, is not in-
tended for the transmission of message traffic but may be
found helpful in contacts with neighboring message centers,
transmission agencies, and offices relative to the transmission
and delivery of messages.
b. Normal form. — The following table lists the data of
interest to the message center which should appear, in whole
or in part, on messages to be transmitted by electrical means
in the normal form. Transmission of messages by radio in
the normal form is used only between divisions, and higher
units.
CJeneral
division
Part
Example
When used
Heading
Text_
Destination. __
Operating instructions. .
Classification
Group <»Lmt_ ^
Dale of origin.
Writer's number _.
/Send to BA.1 or .
fFiend to I nnrps.
P or O and/or Y _
0, P, or NITE
OE? ..
Ti ATE, or SIXTEENTH.
NR2li
jAiwaya.
If required.
If required.
Always.
Always.
If available.
If esseTitM.
Aiways.
Always.
Code or cipher indicator.
Message
Time signed..
DFCT1
1X0W VAWL GOTZ
UKZH.
638P
37
37-38
SIUNAL COMMUNICATION
c. Abbreviated form. — The following table lists the data of
interest to the message center which should appear, in whole
or in part, on messages to be transmitted by electrical means
in the abbreviated form. The abbreviated form, is the only
form authorized within the division for transmission of mes-
sages by radio. The abbreviated form may be used between
divisions and higher units if desired.
General
division
Part
Example
Wlien used
Heading
Teit
Destination
Operating instructions. .
Classification
Code or cipher indicator.
McssEigO-— .... . -— .
Time signed
FSimd to FA1 or—- —
1 Send to 1st FA
P or O and/or Y.
0
DFOT1
IXOW VAWL OOTZ
UKZH.
72«P
jAlways.
If required.
TJrgentmessage
only.
If essential.
Always.
Always.
■ 38, Army and Navt Methods of Specifying Time. — a. The
ordinary 12 -hour clock will be used in the Army. The new
day starts at midnight. Time will be transmitted in three
or four numeral groups with an "A" added if before noon
and a "P" added for all times after noon to midnight. The
words "noon" and "midnight" are used for those times.
b. The Navy uses the 24 -hour clock. Navy 24-hour time
is always expressed as a group of four numerals. The first
two numerals of the group denote the hour and the last two
numerals the minute after the hour. Ordinary or 12-hour
time may be converted to 24-hour time by adding 12 hours
to all times from 1:00 P. M. to midnight inclusive.
e. Examples of time as expressed in the Army and Navy
are shown below:
Time
Navy
Midnight.
12:01 a. m.
1:17a. tn..
11:35 a.m.
2400
0001
0117
1135
Army
Noon
1259P
BD8P-
11S9P
Time
Noon
12:59 p. m .
8:08 p. m
11:59 p. m...
38
SIGNAL COMMUNICATION
39-42
■ 39. Station Lists. — Operation of the message centers of
divisions and higher units is facilitated when station lists are
provided. The station list gives the location of the various
headquarters and elements of the command. It is prepared
by The Adjutant General's Office.
■ 40. Telephone Directory.. — In signal operation instruc-
tions, the message center is furnished the telephone directory
names of all headquarters and the numbers of all offices
with which it may be concerned. Telephone directory names
and numbers are not intended for secrecy but are prescribed
for purposes of simplicity, accuracy, and speed in the han-
dling of telephone calls. (See example on page 280.)
■ 41. Radio, Telegraph, and Visual Call Signs. — In signal
operation instructions, the message center is furnished a list
of the call signs of radio, telegraph, and visual stations with
which it may be concerned. These call signs are used by the
message center to expedite the handling of messages. (See
example facing page 284.)
■ 42. Lettering. — In order to secure legibility in copying
code messages and in other cases where a lettered character
better serves the purpose, the following system of lettering
is prescribed. The examples shown below indicate how let-
ters and numerals should be formed and the sequence to be
followed in making the various strokes:
The straight line I is the foundation stroke. The letters E,
Z, X, and K are made slightly smaller at the top. The let-
ters H, E, and P have the center horizontal strokes slightly
above the middle. The letters X, Y, and K have the junction
slightly above the middle.
39
43-43
SIGNAL COMMITN1CATION
The letters O, Q, C, and G are made in circular form. The
letter B is slightly smaller at the top and has the center
horizontal part slightly above the middle. The letters R and
S are slightly smaller at the top.
The bar under the numeral 1, the top of the 5 and 7, and the
bottom of 2, are straight lines. The numeral 1 has a bar
under it, slightly below the stem, to distinguish it from the
letter I and the cipher 0 has a bar diagonally through it to
distinguish it from the letter O.
Section V
MILITARY CRYPTOGRAPHY
■ 43. Use of Cryptograms. — All messages to be transmitted
by radio or other means, when danger of hostile interception
exists, are cryptographed except in the following cases:
a. When the tactical situation is such that time cannot be
spared for cryptographing and when the information to be
transmitted, if intercepted by the enemy, cannot be acted
upon in time to influence the situation in question, a com-
40
SIGNAL COMMUNICATION
43-44
manding officer or his authorized representative may order
the transmission of a message in plain language by a radio
station serving his headquarters or command. Such written
messages will be marked "Send in clear," over the signature
of the commander or his authorized representative.
o. Commanders may authorize the normal transmission of
artillery fire-control messages in clear,
c. All cryptographing and decryptographing of messages
at a headquarters are performed in the message center,
except as authorized in paragraph 32, unless the message
requires a code or cipher not in the possession of the mes-
sage center. The message center Is provided with the author-
ized codes, cipher devices, and keys.
d. H it becomes necessary to modify the wording of a
message in order to cryptograph it or to facilitate crypto-
graphing, thei modified text will toe submitted to the writer
for approval before transmission.
■ 44. Definitions. — A knowledge of the following terms is
essential for all personnel handling code and cipher mes-
sages:
a. "Plain text," '.'clear text," or "plain language" is the
text of a message which, on its face, conveys an intelligible
meaning in a spoken language.
b. "Secret text" or "secret language" is the text of a mes-
sage which, on its face, conveys no Intelligible meaning in any
spoken language. The secret text of a message constitutes, a
cryptogram.
c. "Cryptography" is the science which embraces all the
methods and devices whereby plain text may be converted
into secret text.
d. "Cryptograms" are of three fairly distinct types as
follows :
(1) Cipher. — A cryptogram in cipher is one which has been
produced by taking the individual letters of the plain text as
units and applying to them either or both of two crypto-
graphic processes known as "transposition" and "substitu-
tion" explained below. The resulting secret text is called
"cipher text" and the operation of producing it is called
"enciphering"; the reverse operation, that of reproducing
41
44
SIGNAL COMMUWICATKHT
the plain text from the cipher text by a direct reversal of the
steps involved in its enciphering, is called "deciphering."
The basis of every cipher system is an agreement between
correspondents covering the general method and the steps to
be followed in cTyptographing. That portion of the agree-
ment which specifically controls the steps under the general
method is termed the "key." The key is usually of a variable
nature, changeable at the will of the correspondents. Nor-
mally it consists of an easily remembered word, phrase, or
sentence; or of a number or series of numbers derivable from
a word, phrase, or sentence.
(a) Transposition cipher. — The cryptographic process
known as transposition consists in rearranging the letters
constituting the plain text (rarely syllables or whole words)
so that the resultant text becomes unintelligible. The let-
ters undergo no change in identity; only their relative order
is altered. A cryptogram which has been produced in this
way is termed a "transposition cipher."
(b) Substitution cipher, — The cryptographic process known
as substitution consists in replacing the letters constituting
plain text by other letters, figures, symbols, or the like. Here
the letters undergo a change in identity without a- change in
their relative order. A cryptogram which has been produced
in this way is termed a "substitution cipher."
<c) Combined- cipher. — When both of these processes have
been applied in producing a cryptogram, the latter is termed
a combined -"substitution-transposition cipher."
(2> Code. — (a) A cryptogram in code is one which has been
produced by taking whole sentences, phrases, words, letters,
or numbers of plain text as units and replacing them by
arbitrary groups of symbols given as their equivalents in a
code book. The resulting secret text is called "code text"
and the operation of producing it is called "encoding"; the
reverse operation, that of reproducing the plain text from
the code text by reference to the code book, is called "decod-
ing." A one-part code consists of only one section which
serves for either encoding or decoding. A two-part code
consists of two sections, one section arranged to facilitate
encoding and the other to facilitate decoding. A one-part
code is very much less secure than a two-part code.
42
SIGNAL COMMTTNICATION
44-45
(&> Code groups or code words are arbitrary groups of
symbols constituting code text. They usually consist of let-
ters or figures or rarely of both letters and figures.
(3) Enciphered code. — A cryptogram In enciphered code
Is one which has been produced by first encoding the plain
text and then enciphering the code text.
e. To "cryptograph" a message is to convert its plain text
into secret text. This is a convenient term to use in refer-
ring to the processes involved without indicating or specify-
ing whether they are methods of enciphering or encoding.
/. To "decryptograph" a message is to reconvert its secret
text into plain text by a direct reversal of the operations
involved in its cryptographing. This is a convenient term to
use in referring to the processes involved without indicating
whether the cryptogram is in cipher, in code, or in enci-
phered code. As enciphering and encoding are forms of
cryptographing, so deciphering and decoding are forms of
decryptographing.
Sf. "Cryptanalysis" is the name applied to the steps and
processes involved in converting cryptograms (usually of
hostile origin) into plain text by means other than those
normally employed in decryptographing messages of friendly
origin.
■ 45, Safety Afforded by Cryptography. — Codes and ciphers
are used in messages for either or both of two purposes;
condensing messages and maintaining secret, except from
the addressee, the contents of messages. "Unless secrecy is
accomplished with certainty, all of the additional time, labor,
and danger of error involved in cryptographic messages is
wasted; moreover, the correspondents may be lulled into a
false sense of security in the belief that their messages are
secret, when, in fact, the enemy may have cryptanalyzed
them and taken action accordingly. With the increased use
of radio as well as other means of electrical communication,
the safeguarding of codes and ciphers has assumed a para-
mount importance. In general it may be stated that no
cryptographic system suitable for a voluminous official cor-
respondence is absolutely proof against the organized, co-
operative efforts of a large and well-trained staff of crypt-
43
45-46
SIGNAL COMMUNICATION
analysts. Practically every cipher system that has ever been
employed for military purposes has been solved and practi-
cally any code book can be reconstructed by analysis, given a
sufficient number of cryptograms and the personnel and
time necessary to accomplish it.
■ 46. Comparison of Codes and Ciphers. — Each of these
two general methods of secret communication is needed in
the military service. The principal factors to be taken into
account in comparing code and cipher methods as systems of
secret communication are —
(1) Simplicity, rapidity, practicability.
(2) Secrecy,
(3) Accuracy.
(4) Economy.
b. In general, it may be said that code is a more rapid
and more simple method of secret communication than is
cipher. The processes of enciphering and deciphering re-
quire very close mental attention to avoid errors, and are
usually much slower than those of encoding and decoding
which more nearly approach automatic processes and thus
require less concentrated mental effort. This is of greatest
importance in the combat zone. There are some very small
cipher devices which tend to reduce the mental strain to a
minimum, but in general the cryptograms they yield are not
as secret as those produced by a good code, especially when
many messages are available for interception by the enemy.
c. Code systems are, on the whole, more secret than cipher
systems, depending upon —
(1) The type of code. A two-part code is more secret
than a one-part code.
(2) The extent of its vocabulary or contents.
(3) The extent to which the code is used; that is, the
number of messages transmitted.
d. Furthermore, the solution of one message does not as
a rule entail the immediate breakdown of the whole system,
with the consequent solution of all other messages in the
same key, as is the case in ciphers. On the other hand, in
the case of code it is absolutely necessary to guard at all
times the cade book so that it does not fall into the hands of
44
SIGNAL COMMUNICATION
the enemy. Actual possession is not always necessary, for
a single opportunity to copy or memorize certain portions
is sufficient to compromise the whole code,
e. On the whole, it may be said that code systems are leas
accurate than cipher systems and are more subject to the
necessity for repetition of messages. This is because a mis-
take in one or two code groups may obscure, alter, or render
unintelligible the meaning of a' whole message, whereas, in
the case of ciphers, the meaning of a few letters which are in
error may be supplied by the context,
/. Since code text is usually shorter than the equivalent
plain text, the latter is more economical to handle than
cipher. This is of great importance where the amount of
signal traffic is heavy. On the other hand, for the purpose
of maintaining secrecy in military communication, codes of
the two-paTt type must be changed rather frequently. This
necessitates repeated processes of preparation, printing, and
distribution, all of which take much time and labor.
■ 47. Authorized Military Codes, — See AR 380-5 for the
manner In which codes are authorized to be used. Among
others, the codes listed below are authorized for general use
in the military service. See paragraph 100 for their code
indicators and the number of characters per code group.
Training and maneuver editions of certain confidential codes
are given a restricted classification when published. Blank
groups are left in codes for the assignment of special mean-
ings by commanders. These meanings are published in sig-
nal operation instructions as supplements to the codes. (See
examples on pages 266 and 268.)
a. War Department Telegraph Code. — This code is a non-
secret code primarily intended for economy. It furnishes no
security from code experts and should never be used for
encoding secret messages. It is issued to all those who are
required to handle any considerable volume of business by
telegraph, radio, or cable.
b. Division Field Code. — This code is issued to message cen-
ters of divisions and all lower tactical units down to and
including the battalion, and in peacetime for training pur-
poses, it may be issued down to companies.
181584°— 39 4 45
4=7-48
SIGNAL COMMUUICATION
c. Aerial Observation Codes and Panels. — These codes are
prepared by the War Department or the headquarters of
the field forces and are issued to all units that engage in
communication between ground and air.
(1) The Fire-Control Code is fixed and is used in adjust-
ment of fire.
(2) The Air-Ground Liaison Code is employed in genera]
observation and reconnaissance. In emergencies it may also
be used in the absence of other cryptographic means for
communication between forward ground stations. It is re-
vised frequently for purposes of secrecy by rearrangement of
code groups and their meanings.
d. Special codes. — Such codes as address and signature
codes, map coordinate codes, geographic, meteorological, and
supply catalog codes, as well as appendixes to the various
codes listed above, will be published from time to time.
e. Prearranged messages. — In traffic by radiotelephone, it
is often desirable to use some form of prearranged message
or groups of letters to indicate meanings which will not
readily be apparent to the enemy. These messages or groups
will be changed frequently and may be prepared by local
commanders as appropriate. These codes or messages being
of a temporary nature, the prohibition as to mixing of clear
and secret text does not apply. A map coordinate code is
particularly appropriate for use in conjunction with such
messages. For example, "Advance guard motors move for-
ward to next position" might be transmitted as "CJ" or a
prearranged phrase might be used instead of a letter group.
For example, "Objective taken" might be transmitted "The
fox is in his hole."
■ 48. Authorized Military Ciphers. — Among others, the fol-
lowing ciphers are authorized for use in the military service:
a. Cipher device M-94.~ This cipher device is explained in
section VI,
o. Telegraph printer cipher system.— This is a cipher sys-
tem operated in connection with telegraph printers and is
used only between the higher headquarters where traffic is
very great.
46
SIGNAL COMMUNICATION
49
■ 49. Rules for Use of Codes and Ciphees <AR 380-5) . — The
following general rules govern the use of codes and ciphers :
a. The instructions contained in each code book or fur-
nished with each cipher system must be carefully studied
and thoroughly understood before the code or cipher is used.
ft. Care should be exercised to prevent the loss or com-
promise of a code book or cipher key. If a code book is lost
or possibly compromised, the fact should be reported
promptly to higher headquarters.
e. Except in emergency, no code or cipher which has not
been approved by higher authority should be employed
within any unit.
d. Care should be exercised that only one edition of a code
of a particular class, or only one cipher key is being used
within a unit at one time. When a code Is replaced by a
new code or a new edition, the replaced code will be de-
stroyed by burning unless otherwise ordered.
e. Cryptographic messages should be short and concise.
Long messages facilitate solution by the enemy.
/. Never repeat a message in a code or cipher other than
the one In which it was originally sent. If the enemy has
already solved one of the codes or cipher keys used, he will
translate the message by that code or cipher key and will
thus be given clues to the solution of the other code or cipher
key.
g. Never cryptograph a message which has been sent pre-
viously in clear and never send a message in clear whieh has
been sent previously as a cryptogram. If the enemy com-
pares the cryptographic message with the clear message he
will be able to break into the code and solve other messages,
or in the case of ciphers, he will have the key for the solu-
tion of all other messages.
h. Never mix secret and clear text in the same message ex-
cept as permitted in paragraph 47e. This applies also to
abbreviations and signs of punctuation which are equivalent
to clear text. If clear text of any kind whatever is left in
the message, the enemy can more easily discover the meaning
of the secret text. If cryptographed at all the entire mes*.
sage must be cryptographed.
47
49-51
SIGNAL COMMUNICATION
i. A cryptographed message never should be filed with the
clear message. (See par. 34ti.)
j. Capital letters should be employed throughout in writing
cryptograms in order to avoid errors. In the case of code,
the grouping of the letters of the code text corresponds to
the length of the cod© groups as given by the book; in the
case of cipher, the text is written and transmitted in groups
of five letters. (See par. 42.)
Section VI
DESCRIPTION AND USE OF CIPHER DEVICE M-94
■ 50. Purpose and Distribution. — Cipher device M-94 is a
cryptographic instrument that is an item of equipment issued
by the Signal Corps to all message centers as one of the au-
thorized means for secret communication. It is also an item
of equipment possessed by all naval units and stations,
including those of the Marine Corps, and can be employed
in certain classes of secret intercommunication between the
Army and the Navy when specific arrangements therefor
have been made by the appropriate commanders.
■ 51. Description. — a. The device is made of aluminum alloy
and consists of the following parts:
(1) A central shaft, the left end of which terminates with
a projecting shoulder, the right end of which is threaded.
(2) A set of 25 alphabet disks, on the rim of each of which
there is stamped a different, completely disarranged alphabet.
(3) A guide-rule disk, consisting of a blank or unlettered
disk from which projects a guide rule,
(4) A retaining plate, consisting of a thin disk upon one
surface of which is stamped the name and type number of the
device.
(5) A knurled thumb nut.
b. Each disk has a hole at the center suitable for mounting
it upon the central shaft upon which the disk can be re-
volved forward or backward. The left face of each alphabet
disk is provided with a circle of 26 equidistant slots; the
right face is cupped and carries at one point on the inside
rim of this cup a small projecting lug. The guide-rule disk
48
SIGNAL COMMUNICATION
51-53
also carries such a lug. When the disks are assembled upon
the shaft, the lug on each disk engages with one of the slots
on the adjacent disk on the right and thus the disks can be
held in engagement in any desired relative positions by
screwing down the knurled thumb but against the retaining
plate which is inserted between the last alphabet disk and
the nut.
c. When the thumb nut and the retaining plate are re-
moved and the alphabet disks are taken off the shaft, it will
be noted that each alphabet disk is stamped on its inside or
cup surface with an identifying symbol consisting of a num-
ber that is above the central hole and a letter that is below
it. The numbers run from 1 to 25, inclusive, the letters from
B to Z, inclusive. These symbols are employed to designate
the sequence in which the alphabet disks are to be assembled
upon the shaft in cryptographing or decryptographing mes-
sages as described in paragraph 53. Either symbol may be
used for this purpose (as prearranged) but for the present
only the numerical identifying symbols will be so used.
■ 52. Necessity for Key and Providing for Changes There-
in,— a. Messages cryptographed by the same sequence of
alphabet disks can remain secure against solution by a well-
organized and efficient enemy cryptanalytic section for only
a relatively shoTt time. It is impossible to state exactly how
long, because solution -depends upon a number of variable
factors; a conservative estimate would place the minimum
at 6 hours, the maximum at 2 or 3 days. For this reason it
ts necessary to change the sequence from time to time, and
the method for determining or indicating the new sequence
must be agreed upon in advance and thoroughly understood
by all who are to use the instrument.
b. The sequence in which the alphabet disks are assem-
bled upon the shaft constitutes the key in this cipher sys-
tem. When a change in key is to take place, exactly what
the new key will be and the exact moment that it is to super-
sede the old key will be determined by the proper com-
mander and will be published in signal operation instructions.
(For example, see page 272.)
49
53
SIGNAL COMMUNICATION
■ 53. Detailed Instructions for Setting Device to a Pre-
determined Key.— a. The method prescribed herein is based
upon a key word or key phrase from which the sequence oi
numbers constituting the key for assembling the alphabet
disks may be obtained by following a simple, standardized
procedure. The reason for employing such a procedure is
that it makes it possible to derive at will a relatively long
sequence of numbers (which woul dbe difficult to remember)
from a word or phrase (which is easy to remember) and
thus eliminates the necessity of carrying the key in written
form upon the person. It is this basic key word or key
phrase which is communicated throughout the command in
signal operation instructions. The exact method of deriv-
ing the numerical key sequence from the key word or key
phrase is given step by step in b below.
b. Assume that the key phrase so communicated is CHI-
NESE LAUNDRY. The following are the detailed steps to
be followed in deriving the numerical key sequence:
(1) A set of rows of cross section squares, 25 squares in
each row, is prepared. (Prepared sheets of %-inch squares
are suitable.)
(2) In the top row the series of numbers 1, 2, 3-25 are
inserted. Thus:
i 2 j u t u no mi im t.i le n is in 20 21 22 23 24 26
(3) Beginning under the number 1, the successive letters
of the key phrase are written in the second row of squares
under the successive numbers. Thus:
1, 2 3 4 i 6 7 8 B 10 11 12 13 14 16 Hi 17 18 19 20 21 22 23 24 26
CHINESELAUNDRY
(4) The key phrase is extended by repetition until there
is a letter under the number 25, making a key sequence of 25
letters. If the key consists of a word or phrase containing
50
SIGNAL COMMUNICATION
53
more than 25 letters, those after the twenty-fifth letter are
merely omitted. Thus:
~ 2 3 4 5 (i 7 8 9 in i I 12 13 14 15 1(1 17 18 19 20 21 22 23 24 25
CHINESELAUNDRYCHINESELAUN
(5) The letters of the key sequence are now numbered
serially from left to right in accordance with the relative
position that each letter occupies in the ordinary alphabet.
Since the letter A comes first in the ordinary alphabet and
since this letter occurs twice in the illustrative key sequence,
the number 1 is written under the first appearance of A in
this sequence and the number 2 is written under its second
appearance. Thus:
1 2 3 4 5 8 7 8 9 10 11 12 13 14 IB 10 17 18 19 20 21 22 23 24 2i>
CHINESELAUNDRYCHINESELAUN
1 2
(6) The next letter in the ordinary alphabet is B. The
key sequence is carefully examined to see if it contains the
letter B. Since this letter does not appear in the illustrative
key sequence, the latter is examined to see if it contains the
letter C. This letter oecurs twice in the illustrative key
sequence and the first C, therefore, is assigned the number 3,
the second C the number 4. Thus:
1 2 3 4 5 6 7 8 9 1(1 II 12 13 14 15 16 17 18 19 20 21 22 23 24 25
CHINESELAUNDRYCHINESELAUN
S 14 2
(7) The next letter in the ordinary alphabet is D, which,
being present in the key sequence, is assigned the next num-
ber, and so on. Thus, the process is continued until each
letter has been assigned a number. The work must be done
carefully so as not to overlook a single letter. If an error is
made in the early stages o£ the work, it necessitates starting
anew. The operator should be especially careful with letters
which immediately follow one another in the ordinary alpha-
bet but are present in the key sequence in reversed order,
such as ED, FE, ON, and so on. It is easy to make a mis-
51
53-54
SIGNAL COMMUNICATION
take in such eases and to assign numbers to these letters
in a sequence that is the reverse of what it should be.
(8) When the numbering process has been completed and
if the work has been correctly performed, it will be found
that every letter of the key sequence has a number under it
and that the greatest number that appears is 25. If this is
not the case, it is an immediate signal that an error has
been made. It cannot, however, be assumed that so long as
every letter has a number under it, with the greatest number
25, this Is immediate and conclusive proof of accuracy in the
work. The operator should invariably check his work; better
yet, if two clerks are available, each one should derive the
numerical key independently and cheek final results by com-
parison.
(9) The key phrase selected as an example in the fore-
going description yields the following numerical key:
1 2 3 4 6 6 7 8 9 10 It 12 13 14 18 10 17 18 19 20 21 22 23 24 26
CHINESELAUNDRYCHINESELAUN
3 10 12 16 6 21 7 14 1 23 17 5 20 25 4 11 13 18 8 22 fl IS 2 24 L9
(10) It is this sequence of numbers which indicates the
order in which the successive alphabet disks are to be as-
sembled upon the shaft from left to right. Thus, according
to the foregoing key sequence, alphabet disk No, 3 comes
first, that Is, immediately to the right of the guide-rule disk;
alphabet disk No. 10 comes next, and so on. Alphabet disk
No, 19 is the last in this particular key, and after it has been
placed on the shaft, the retaining plate and thumb nut are
added and the latter screwed down a distance sufficient to
keep the assembly together and yet permit of revolving in-
dividual disks freely upon the shaft. The device is now
ready for use in either cryptographing or decryptographing
messages.
■ 54. Cryptographing a Message. — Suppose the following
message is to be enciphered with the key used in paragraph
53:
CO 3d INF
HAVE JUST REACHED EASTERN EDGE OP WOODS
ALONG 552-592 ROAD WILL REMAIN IN OBSERVATION
CO 2d BN
52
SIGNAL COMMUNICATION
54
a. The message is written down on the work sheet under-
neath the key lines of 25 letters each. Space is left under
each line for the insertion of cipher letters. For procedure
in connection with abbreviations and numbers appearing
in the text of messages, see paragraph 55. Thus:
12 3 i 5 0 7 8 9 10 11 12 13 U 15 lfl 17 IS lfl 20 21 22 23 24 2S
CHINESELAUNDRYCHINESELAUN
3 10 12 lfl 6 21 7 HI 23 17 5 20 24 4 11 13 18 8 22 9 10 2 24 lfl
HAVEJUSTREACHEDEASTERNEDG
EOFWOODSALONGFIVEFIVETWOD
ASHFIVENINETW0R0ADWILLREM
AININOBSERVATION
b. By revolving the disks upon the shaft one by one, the
first 25 letters of the message are alined to form a continu-
ous horizontal row of letters reading from left to right along
the outside of the cylinder. The guide rule will be found
very convenient in marking the row upon which the letters
are being alined, thus relieving the eyes of unnecessary
strain and reducing the chance of making errors. After all
25 letters have been, alined, the assembly is locked in posi-
tion so that no disk can become displaced accidentally in
further manipulation of the cylinder. The row of letters is
immediately checked to make sure that no displacement has
occurred among the first few disks vMile manipulating the
last few.
c. The outside of the cylinder now presents a series of 26
rows of letters of which 24 rows are fully visible, the other
two being hidden or partially obscuied by the guide rule.
53
54
SIGNAL COMMUNICATION
One of the 24 visible rows is the plain-text row, that has just
been set up and the other 23 rows are cipher-text rows any
one of which may be selected to represent the plain-text
row. One of these cipher-text rows is selected at random
and the letters composing this row are written underneath
the row of plain-text letters on the work sheet. Thus, sup-
posing the row beginning JtJKLD has been selected, the first
cipher line will read as follows:
1 2 'i 4 5 6 7 8 9 10 11 12 13 14 IS 18 17 13 19 20 21 22 23 24 25
CHINESELAUNDRYCHINESELAUN
i ID 12 16 6 21 7 14 1 23 17 5 20 25 4 II 18 IS S 22 9 15 2 24 19
HAVEJUSTREACHEDEASTERNEDG
JUKLDYKITZIIVCYCVUYVPYWHJ
It is not necessary to make any record on the work sheet
as to which cipher-text row (above or below the plain-text
row) was selected, nor is It necessary to indicate it in any
manner whatever in the cipher message.
d. The thumb nut is loosened but not removed from the
shaft. The next 25 letters of the message are alined, the
thumb nut screwed down against the retaining plate, the
letters in the alinement are checked, and again any one of
the 23 visible cipher-text rows, except the one used to enci-
pher the first line, is selected at random for the cipher text.
The letters in the row selected are written down under the
second line of plain-text letters on the work sheet. Thus,
supposing the row beginning YUYEZ was selected, the work
sheet now appears as follows:
1 2 3 4 S 6 7 8 9 10 11 12 13 14 IS 18 17 18 ID 20 2L 22 23 24 25
CHINESELAUNDRYCHINESELAUN
3 10 12 16 6 21 7 14 1 23 17 5 20 25 4 1] 13 18 S 22 9 15 2 24 19 ~
HAVEJUSTREACHEDEASTERN E~DG~
JUKLDYKITZIIVCYCVUYVPYWHJ
EOFWOODSALONGFIVEFIVETWOD
YUYEZDHVUZDBQ POZMCFNBJJIX
54
SIGNAL COMMUNICATION
54
e. This process is continued in similar manner with the
third line of the plain-text message. It should never be
made a practice to "favor," that is, frequently to select a
particular cipher-text row above or below the plain-text rom.
As irregular a selection as possible should be made, and the
selection of the cipher-text row immediately above the plain-
text row or immediately below the lower edge of the guide-
rule should be avoided. Suppose these instructions have been
followed and that there has been selected for the cipher-text
row representing the third plain-text line of the message the
row beginning EAPTH, the message now stands as follows r
'l 2 1 ( S 6 I 8 J 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
chineselaundrychine'selaun
3 111 12 It 6 81 7 14 1 a 17 5 2D 25 4 11 18 IB 8 22 ft 15 2 24 19 ~
HAVEJUSTREA CHEDEASTERNE D~G~
JUKLDYKITZIIVCYCVUYVPYWHJ
E0FW00DSAL0NGFIVEFIVETW0D
YUYEZ DHVUZDBQPOZMCFNBJJIX
ASHFIVENINETWOROADWILLREM
EAPTHYOWHKWWTNYGMPRZJIFAD
/. There are left only 16 letters to be enciphered, not
enough to make a complete row of 25 letters. This, however,
makes no difference in procedure; these 16 letters are merely
alined and a cipher-text row is selected to represent them.
Supposing the row beginning MEQRH is selected, the mes-
sage now stands as follows:
1 2 » « S t U 8 10 II 12 II W 16 16 17 18 18 20 21 22 23 24 25
CHIMESELAUNDRYCHINESELAUH
3 10 12 16 6 21 7 14 1 23 17 8 20 25 4 11 13 IS S 22 0 15 3 24 19
HAVEJUSTREACHEDEASTERNEDG
JUKLDYKITZIIVCYCVUYVPYWHJ
55
54 SIGNAL COMMUNICATION
EOFWQODSAL0NGFIVEFIVETW0D
YUYEZDHVUZDBQPOZMCFNBJJ IX
ASHFIVENINETWOROADOTILLREM
EAPTHYOWHKWWTNYGMPRZJIFAD
A I N I N 0 B 5 E R V A T I 0 N
MEQRHBPOJTYUQNTW
g. The cipher text is now copied on the message form in
5-letter groups. It is as follows:
JUKLD YKITZ IIVCY CVUYV PYWHJ
YUYEZ DHVUZ DBQPO ZMCFN BJJIX
EAPTH YOWHK WWTNY GMPRZ JIFAD
MEQRH BPOJT YUQNT W
h. The last group of the cipher message is, however, not a
complete group of 5 letters. It is made so by adding four X's.
These are not to be cryptographed; they are added merely
to complete the last cipher group. The final message be-
comes as shown below:
JUKLD YKITZ IIVCY CVUYV PYWHJ
YUYEZ DHVUZ DBQPO ZMCFN BJJIX
EAPTH YOWHK WWTNY GMPRZ JIFAD
MEQRH BPOJT YUQNT WXXXX
The message as it now reads is but one of many different
forms in which this same message could appear externally,
56
SIGNAL COMMUNICATION
b'4-56
depending on exactly which of the available cipher-text rows
is selected for each line of the encipherment.
■ 55. Cryptographing Abbreviations, Punctuation Signs,
and Numbers, — a. Authorized abbreviations appearing in the
original plain-text message may be enciphered as abbrevia-
tions without periods. Examples: Am Tn=AMTN; E, V.
Brown Seh=EVBROWNSCH,
b. Normally the writer of a message spells out the punctua-
tion signs he wishes transmitted, for example, STOP,
COMMA, COLON, etc. If a message contains punctuation
signs not so spelled out, they are spelled out and trans-
mitted.
c. Cardinal and ordinal numbers when spelled out in letters
in the original plain-text message are always enciphered
exactly as spelled.
d. Cardinal numbers when expressed in figures in the orig-
inal plain-text message must always be spelled out digit by
digit in cryptographing. Examples:
4=FOUR
40=FOURZERO (not FORTY)
400=FOURZEROZERO (not FOUR HUNDRED)
455 =FOURFTVEFIVE
2005=TWOZEROZEROFIVE
12.01 A. M. = ONETWOZEROONEAM
5.15 P. M.=FrVEONEFIVEPM
e. Ordinal numbers above the ordinal number 10th, when
expressed in figures followed by "d," or "th," are crypto-
graphed merely as digits spelled out without adding the "d"
or "th". The omission of the "d" or the "th" will cause no
confusion or ambiguity. Examples: 3d Bn=THlRDBN; 7th
Pack Tn=SEVENTHPACKTN; 11th Regt=ONEONEREGT;
403d Am Tn=FOURZEROTHREEAMTN.
■ 56. Decryptographihg a Message. — a. Knowing the key
word or key phrase, the numerical key is developed as de-
scribed in paragraph 53 and the set of alphabet disks is
assembled accordingly. The message to be decryptographed
is written down in lines of 25 letters on cross section paper,
if available, space being left under each line for the insertion
57
56
SIGNAL COMMUNICATION
■of plain-text letters. Using the cipher message given in par-
agraph 54ft, it appears under the key in the following form:
1 2 3 4 5 tt 7 S 9 ID 11 12 13 U 15 16 17 18 19 20 21 22 23 21 SB"
CHINESELAUNDRYCHINESELAUN
S 10 12 16 6 21 7 14 1 23 17 5 20 25 i 11 13 18 S 22 » 10 2 24 19
JUKLDYKITZIIVCYCVUYVPYWHJ
YUYEZDHV UZDBQPOZMCFNBJJIX
EAPTHYOWHKWWTNYGMPRZJ I F A D
MEQRHBPOJTYUQNTW
b. The first 25 letters of the cryptogram are set up on the
device, the letters being alined in a row from left to right
just above the guide rule. Fixing the disks in this position
by screwing down the thumb nut, the whole cylinder is
turned slowly, forward or backward, and each row of letters
is carefully examined. One of these rows and only one will
read intelligibly all the way across from left to right. That
is the row which gives the plain text for the first 25 cipher
letters. These letters are inserted in their proper place on
the work sheet, giving the following:
i 2 3 4 H fi 7 8 9 10 11 12 13 14 15 Hi 17 18 IV 20 21 22 23 'H 25~
CHINESELAUNDRYCHINESELAUN
3 1U 12 1U ti 21 7 11 I 23 17 ft 20 25 4 U 13 IS S 22 9 15 2 24 19
JUKLDYKITZIIVCYCVUYVPYWHJ
HAVEJUSTREACHEDEA5TERNEDG
e. The thumb nut is then loosened, the next 25 cipher
letters are set up, the assembly is locked into position, again
S8
SIGNAL COMMUNICATION
56-57
the whole cylinder is slowly revolved, and the plain-text row
of letters found. These are written down in their proper
place and the process is continued with the rest of the cipher
letters until the message has been completely decrypto-
graphed.
d. In the case of a cryptogram the last few letters of
which do not form a complete set of 25, if any difficulty is
experienced in picking out the plain-text row, the context of
the preceding part of the message should give a good clue.
In the case of the illustrative message above, it should be
realized that the last four letters of the cryptogram are not
to be decryptographed since they are merely added after
cryptographing to make the last group of the cryptogram
a complete group of five letters. They are omitted from the
work sheet.
e. The plain-text message Is then copied on. a message
form. The code clerk may, if authorized to do so by the
message center chief, convert numbers which had to be
spelled out in letters to permit of their cryptographing into
their equivalent arabic figures. Abbreviations and punctu-
ation signs are, however, copied exactly as they stand in the
decryptographed message.
■ 57. Precaution. — When in danger of capture, the alpha-
bet disks of a device that has recently been used to crypto-
graph or decryptogravh a message must be taken off, thor-
oughly disarranged, and reassembled.
59
58-59
CHAPTER 3
MESSENGER COMMUNICATION
rurugrarJis
Section I, General.
II. Training of personnel.
III. Employment
IV. Dropped messages
V. Pick-up o! messages-.
58- eo
61-66
67-76
77-fiO
81-85
Section I
GENERAL
■ 58. Necessity. — Messenger communication is needed and
used by all units from the smallest to the largest. Both per-
sonnel and equipment are necessary for messenger communi-
cation, but of all means of signal communication, it is most
dependent upon personnel, and only to a minor degree upon
equipment. All persons in the military service are enjoined
to assist messengers carrying important orders or messages
by pointing out the route, giving directions, and providing
transportation if necessary.
■ 59. Personnel. — a. The personnel needed for messenger
communication consists primarily of messengers; hut agents,
airplane pilots and observers, and others are required in
special situations. Usually messengers are a part of message
center sections of units operating a message center, but if
they are not, they should be attached to those sections for
training and employment.
(1) Messengers are persons who carry messages as defined
in paragraph 5. In the field a dismounted messenger is
named a runner. Other messengers are named according
to the means of transport used by them; as, mounted <horse> ,
bicycle, motorcycle, motor, and airplane.
(2) Agents are defined and their duties are prescribed in
other publications.
b. Because of the great dependence of messenger com-
munication upon the personnel used in it, that personnel
60
SIGNAL COMMUNICATION
59-61
should be selected with the following characteristics as a
basis:
(1) Motorcycle, bicycle, mounted messengers, and runners
should be young and sturdy.
(2) Messengers, especially Tunners and agents, require
courage to a marked degree. They are often sent on im-
portant missions the accomplishment of which requires ex-
traordinary self-reliance and endurance.
(3) Messengers and agents require an intelligence above
the average. They must be able to comprehend simple oral
orders, to use compasses and maps, and to understand
changes in tactical situations. They must be resourceful.
(4) Extreme loyalty is necessary to insure trustworthiness.
In messengers, loyalty and courage will compensate to some
extent for deficiencies in physique. These men must carry
out their instructions and duties with care and certainty.
■ 60. Equipment. — All messengers should be provided with a
red brassard and agents should be provided with a blue
brassard worn on the left sleeve above the elbow (AR 600-35
and 600-40), and when necessary, with a compass and a
message carrying bag. In addition, all except runners and
some agents, require some means of transportation. A motor
messenger may be the driver of a vehicle or he may be an
additional occupant, depending upon the circumstances.
Commanders of all units may find it necessary in an emer-
gency to utilize, for messengers, any motor vehicle assigned
to their units. An airplane may have solely a messenger
mission, it may perform such a mission in addition to its
other work, or it may be used only to transport an ordinary
messenger. See sections IV and V for the equipment neces-
sary for dropping and picking up messages by airplane.
Section II
TRAINING OP PERSONNEL
■ 61. Basic— See TM 2260-5 for the minimum training
specifications lor signal specialists, and particularly those
for a basic private, a basic corporal, and a basic sergeant.
The training given in the paragraphs below for messengers,
181584°— 39 5 61
61-64
SIGNAL COMMUNICATION
except airplane pilots or observers, follows the completion of
the training for a basic private and that for agents follows
the completion of the training for a basic corporal or
sergeant.
■ 62. Runner. — The runner will be qualified in —
a. Transmitting oral and written messages.
b. Traveling across country over various kinds of ground
at the prescribed rates. (See par. 70.)
c. Using a compass as a means of orientation and as a
means of following a given azimuth.
d. Beading maps and orienting himself by stars or sun so
as to locate routes, terrain features, and troop positions, and
to be able to follow highways, ravines, streams, and telephone
or telegraph lines.
e. Selecting routes from map or ground that will furnish
the best cover and concealment consistent with time limit of
delivery.
/. Observing and reporting troop movements.
g. Recognition of officers, units, ornaments, and insignia
with which they are associated.
h. Conveying Information and orders by whistle and by
arm and hand signals.
i. Using a delivery list and message envelope.
■ 63. Mounted Messenger. — In addition to the training of a
runner, a mounted messenger will be qualified in—
a. Feeding, watering, and grooming animals,
a. Saddling and bridling animals, and adjusting their
equipment.
c. Care of animals in garrison and field; to include recog-
nition of common ailments, administration of necessary first-
aid treatment, and care of back and feet.
d. Equitation, including riding at all gaits over varied
terrain.
e. Covering specified distances in specified times, all within
the limits of endurance of the animal.
f. Concealing and protecting animals during combat.
■ 64. Bicycle, Motor, and Motorcycle Messengers. — In
addition to the training of a runner, bicycle, motor, and
62
SIGNAL COMMUNICATION
64-68
motorcycle messengers will be qualified in riding, driving,
and earing for the vehicle which, transports them, and in
traveling in accordance with traffic regulations and rules of
the road.
■ 65. Airplane Messenger. — If the airplane messenger is the
pilot or observer, he will be qualified in radio and visual
communication, and in dropping and picking up messages, all
of which are covered elsewhere in this manual. If the air-
plane messenger is an ordinary messenger being transported
by airplane, he should also be trained in the use of a safety
belt and parachute.
* 66. Agent, — The agent will be Qualified in —
a. Transmitting oral and written messages.
&. Receiving and transmitting messages accurately by tel-
ephone.
c. Using the message blank
d. Using the compass.
e. Reading maps.
/. Making a simple sketch.
jr. Observing and reporting troop movements, troop posi-
tions, and terrain features.
. h. An elementary understanding of the organization and
tactical employment of his unit and of the unit to which he
is sent.
Section in
EMPLOYMENT
■ 67. General. — Far other details as to the employment of
messengers, see chapter 2,
■ 68. Selection or Type of Messengers Used. — The effec-
tiveness of messenger communication is largely dependent
upon the selection of the proper type of messenger. This
selection is based upon the UTgency, length or bulk of the
message, terrain, weather, and types of messejagers and
transportation available.
a. Runner. — A runner is used when other means of signal
communication will not function in a dependable manner,
when other means become overtaxed, or when distances are
63
68-69
SIGNAL COMMUNICATION
short or the route is impassable for other messengers. He
is able to go where other types cannot go, and. he can con-
ceal himself more easily. He should not, however, be used
for long distances if it can be avoided.
&. Mounted,, bicycle, and motorcycle. — Messages are sent
by mounted, bicycle, and motorcycle messengers when the
enemy situation and the character of the route permit the
use of horses, bicycles, or motorcycles.
c. Motor, — Motor messengers are used between headquar-
ters widely separated, when the mail service will not suffice.
They may be placed on a routine schedule or may be sub-
ject to call as required.
d. Airvlane. — (1) The commander of a division or higher
unit may assign airplanes to the messenger service when
other means of signal communication will not suffice. Im-
portant messages transmitted between widely separated
units or between allied armies may best be delivered by
airplane.
(2) Messages may be handed on the ground to the pilot,
observer, or a messenger traveling in the airplane, or deliv-
ered to the airplane in flight by radio, panels, pyrotechnics,
pick-up, or other means. (Bee sec. V.)
(3) Messages transmitted by airplane may be delivered
directly by the pilot, observer, or other messenger on the
ground or from the airplane in flight by radio, pyrotechnics,
or other visual means, or by dropping. (See sec. IV.)
■ 69. Receipt of Messages for Delivery. — a. The officer or
noncommissioned officer directing the transmission of a mes-
sage gives the messenger the following information:
(1) Name and location of the headquarters or person to
whom the message is to be delivered.
<2) Route to be followed and dangerous points to be
avoided unless left to his discretion.
(3) Speed required.
(4) Whether or not an answer is expected.
(5) Where to report upon return.
(6) Where to report in case the message is not delivered.
(7) Special instructions, if any.
(8) Contents of the message if the situation warrants.
64
SIGNAL COMMUNICATION
69-70
b. When one or more messages are entrusted to a mes-
senger, a delivery list is attached, or he is directed to obtain
receipts on the envelope.
c The messenger is instructed to report his destination to
the nearest leader when passing an outpost or other line
established by a security detachment. This officer or non-
commissioned officer should orient the messenger and lend
aid, if required, to expedite the delivery. (See par. 58.)
■ 70, Carrying Messages. — a. Messages will be carried in the
message carrying bag when one is provided. If none is pro-
vided, the messages will be carried in the upper left-hand
pocket of the blouse or the left-hand pocket of the shirt.
Bulky packages are carried in the hand or under the arm.
In inclement weather they should be protected by a raincoat
or waterproof covering.
b. When the situation permits, messengers will travel by
covered routes. When approaching or leaving command
posts, messengers will be particularly careful to avoid dis-
closing the location of the post. They should use such meas-
ures as are necessary to insure prompt delivery and to
prevent needless exposures. When practicable, routes over
difficult terrain which may be traversed at night should be
reconnoitered during the day by the messengers who will use
them at night. When necessary they will inquire their way
of troops they may meet.
c. Messengers will be trained to travel, under good road
conditions, at the following prescribed rates given in miles
per hour:
Eurmcr
Mounted
messenger
Bicycle
messenger
Motor and
motorcycle
messenger
Routine
Priority (P) -
Urgent (0)
5
Highest
arrival.
<S
8
speed consi
6
10
stent with
25
40
certainty ol
d. Messengers may be instructed to show unsealed mes-
sages to designated commanders whom they may meet on the
route. Each person reading such a message will initial it.
65
70-71
SIGNAL COMMUNICATION
e. The importance of preventing messages of all kinds from
falling into enemy hands will he impressed upon all messen-
gers. When in immediate danger of capture, messages will
be destroyed. Before destruction, if the circumstances will
permit, their contents will be committed to memory.
/. Messengers found wounded or killed will be searched and
any message discovered will be delivered to the nearest mes-
sage center or commander.
■ 71. Delivery of Messages. — a. For routine delivery of mes-
sages, see chapter 2.
b. Oral messages should seldom be used on account of the
great liability of errors. When used, they should he short
and simple. Messengers deliver them verbatim. A messen-
ger receiving an oral message repeats it back to the sender
so there may be no misunderstanding. The messenger re-
peats it to himself until he has committed it to memory.
c. Messengers may at times be required to wait and carry
back a reply or other messages destined for their own com-
mand. However, their return will not be delayed more than
a few minutes for this purpose.
d. When the headquarters, message center, or the indi-
vidual addressed cannot be found without undue loss of time,
messengers will report to the nearest headquarters and re-
quest instructions.
e. Messengers whose transportation has become disabled
will continue to their destination in the most practicable
manner. It may be advisable to report to the nearest head-
quarters for assistance and instructions. In event of being
incapacitated by wounds, they should turn their messages
and instructions over to any reliable person whom they may
encounter. When such action is necessary they will keep a
record of the person, time, and place and turn it in at the
first opportunity to the message center or to the person from
whom the message was received.
/. Messengers must avoid interfering with marching troops.
In the presence of a person not definitely recognized as a
member of their own army, messengers will make no mention
of the direction from which they have come or of then-
destination,
66
SIGNAL COMMUNICATION
71-73
g. Messengers will help other means of signal communica-
tion to function when it is possible to do so without inter-
fering with their own task. For Instance, if they discover
breaks in wire lines they will report their location.
■ 72. Double Messengers. — Double messengers should be
used when the mission is important or dangerous, such as
movement through hostile territory, past enemy patrols, over
ground swept by small arms fire, or over heavily shelled
areas. Double messengers must keep within sight of each
other yet remain separated by such distance as will prevent
both being exposed to hostile fire or ambush at the same
time. Each should carry a copy of the message. It is some-
times advisable to send messages over several routes at the
same time.
■ 73. Routes. — ft. Routes over which messengers are to travel
usually will be selected by the officer or noncommissioned
officer in charge. They must be chosen with due regard to —
(1) Type of messenger which is to be used.
(2) Concealment from enemy observation.
(3) Availability under existing orders or traffic conditions.
(4) Length and condition.
t>. Roads and villages are habitually marked by the engi-
neers to indicate headquarters and routes. When not
marked by the engineers, messengers may be ordered to
mark them on their first trip over a route, or they may be
detailed specially for the purpose. Arrows or other suitable
trail marks should be placed at crossroads, at changes of
direction, and at frequent intervals along routes to indicate
courses to be followed. The marks must be conspicuous.
c. It may be advisable to send messengers over routes once
by daylight, preferably with other messengers who have been
over the route. Through difficult terrain runners may be
instructed to follow telephone wires maintaining their direc-
tion at night by letting a wire pass through the hand.
Wires, may be laid to guide runners at night or through
dense woods. Alternate routes are selected whenever the
principal route cannot be used because of congestion or
enemy observation or shelling.
67
73-76
SIGNAL COMMUNICATION
d. Messengers should be instructed, so that they will know
the different routes leading to each headquarters or unit to
which they may be sent.
■ 74. Schedttltsd Messengers (par, 27/) . — When periodic
trips are desirable, a scheduled messenger service is arranged
by message centers and the necessary assignment of mes-
sengers made in accordance therewith. The messenger dis-
patcher will equalize the work assigned to messengers.
■ 75. Relay Posts. — Relay posts may be established when
messages must be carried frequently and rapidly between
eertain headquarters or units widely separated or when a
change in the means of transportation en route is necessary.
Motorcycle and motor messengers usually do not operate in
relays. Relay posts established in enemy territory should be
of sufficient strength to provide for their own security.
■ 76. Agents. — a. Below the division all necessary informa-
tion can usually be obtained or distributed through reports
and field orders, though agents prove useful in special cases.
During combat, agents may be exchanged by adjacent pla-
toons or larger units.
6. A headquarters or unit sends out an agent or agents
when the service of information, need of coordination, or
special occasion requires. They may be used for delivering
instructions, for transmitting information, for reconnais-
sance, and for guides.
c. Agents will be instructed regarding the information
which they are to furnish to, and request from, the head-
quarters or unit to which they are sent. These instruc-
tions usually concern the disposition, location, and move-
ment of units, command posts, and headquarters; and the
intention, plan, success, and failure of operations. Agents
will be given information which may be of value to their
respective unit commanders and they will transmit such
information as soon as practicable thereafter.
68
SISNAL COMMUNICATION
77-80
Section IV
DROPPED MESSAGES
■ 77. Use. — Dropped messages are normally received by
units down to and including the battalion; but by prear-
rangement, messages may be dropped to any unit, detach-
ment, or Individual. During heavy shelling by friendly
batteries, dropped messages aTe usually not sent to units in
front of the light artillery positions.
■ 78. Dropping Grounds. — Message dropping grounds or
panel display grounds are located near the radio station.
Panels are displayed on these grounds -when there is a
message for the airplane or when the airplane calls for
panels. A dropping ground should be an open space removed
from high trees, bodies of water, and weeds. (See par. 145.)
■ 79. Procedure. — When an airplane desires to drop a mes-
sage for a particular unit, it makes a prearranged pyrotechnic
or other signal, meaning "display panels" over the unit for
which the message is intended, The unit displays its identi-
fication panel. The message is then dropped by the airplane
as near as possible to the identification panel. On the ap-
proach of a friendly airplane, all ground troops observe the
airplane for a dropped message. Whether or not prear-
ranged signals are made from the airplane, the message will
be picked up by the nearest troops and taken at once to the
unit message center or to the commanding officer,
■ 80. Equipment.-— a. The message bag and streamer are
improvised by air corps personnel, the bag being made of
heavy cloth. It is l^h inches long by 4%, inches wide. In
order to mark for ground troops the line of descent of the
bag and its location on the ground, it has two 72 -inch
streamers, one yellow and one white. Two ounces of sand
are placed in one end so that the bag will fall straight to
the ground. The bag also contains one -fourth ounce of
kapok to keep it afloat If dropped in water. A drawstring
or other suitable means is provided for securely fastening
the message compartment. Printed on the bag are the
words, MAIL OR DELIVER TO THE NEAREST TJ. S. AIR
CORPS TROOPS.
69
80-83
SIGNAL COMMUNICATION
b. Metal tubes are provided by the Air Corps for dropping
maps or photographs; these tubes, made of duralumin, are
93A inches long and 1% inches in diameter. A chrome -
yellow streamer 30 by 3% inches is attached. The tube is
closed by a rubber stopper.
Section V
PICK-UP OF MESSAGES
■ 81. Use. — Messages normally are picked Up by airplane
observers from units down to and including the battalion
when the requirements for a pick-up field (par. 82) can be
met, but by prearrangement, messages may be picked up from
any unit or detachment. This means of message delivery is
available to those ground troops equipped with panels; how-
ever, by prearrangement, panels may be improvised. The
method of pick-up described herein is used when it is desired
to pick up messages or other light packages from localities
where landing fields are not available. In that case, obser-
vation aircraft must carry the equipment required by the
observer and a supply of message bags, and ground troops
must assemble or improvise the equipment required.
■ 82. Pick-up Field. — An open field is selected 300 yards
or more in length with clear approaches up and down wind.
There should be no obstacle in the line of flight of the air-
plane which would keep it from flying close to the ground.
The direction of the wind must be carefully noted as the line
of flight of the ah-plane will be into (against) the wind. The
degree of success obtained will depend largely upon the
selection of the field and the careful lay-out of the equip-
ment,
■ 83. Equipment. — a. Required on the ground. — (1) Two
poles, shelter tent, or suitable substitutes, or two rifles with
bayonets attached.
(2) Two large nails, about 10-penny. (No nails are needed
if shelter tent poles or rifles and bayonets are used.)
(3) Sixty feet of cord about %c inch in diameter, prefer-
ably waxed. If this is not available, any flexible material of
equal strength, length, and weight will suffice.
70
SIGNAL COMMUNICATION
83
(4) Two panels AL-121, AL-122, or suitable substitutes.
These are code and distinguishing panels 12 feet long and 2
feet 4 inches wide.
(5) Two or mora message bags.
b. Required in the air. — (1) Fifty feet of waxed braided
cotton cord of ^c-inch diameter or equivalent.
(2) A leaded weight of about 2 pounds with four hooks
attached to the pick-up end of the cord line.
c. Preparation and arrangement. — (1) The equipment is
prepared as follows:
(a) A large nail is driven through each pole about 6
inches from the top so that the nail point will protrude about
2 inches and point up at an angle of about 45° . It is impor-
tant that the nails be carefully smoothed off so that the cord
cannot foul. If rifles with bayonets attached are used in lieu
of poles, the hilt of the bayonet is used in the same manner
as is prescribed below for the nail. If available, small
streamers attached at the top of the poles will aid the pilot
in locating the equipment.
(o) The cord is then prepared as follows: A 6-inch loop
with a fixed knot is tied in each end of the 60 -foot cord
in such a manner that about 8 inches of cord is left free
from the point where the knot is tied. The message bag is
tied to one free end of the cord and an object of equal weight
to the other free end. Each message bag and message should
weigh about 1 pound. If the weight of the bag and message
is less than 1 pound, some foreign substance of small volume
should be added to make up the weight. This weight, how-
ever, should not be exceeded.
(2) Figure 1 shows the arrangement of the equipment.
Each of the loops in the cord is placed over one of the nails.
The poles are held upright and the cord pulled taut and in
such manner that the points of the nails point into (against)
the wind.
(3) The panels are now laid out, one extending from the
base of each pole in the direction toward which the wind is
blowing. These panels assist in marking the position for
the pilot.
11
83-84
SIGNAL COMMUNICATION
Figure 1. — Arrangement of equipment lor picking up messages oy
airplane.
■ 84. Procedure. — a. Upon receipt of the panel or other sig-
nal meaning "Pick up message at this point", the airplane is
flown over and circles the area until the pilot observes that
the arrangements are in readiness. When all is ready, the
observer lowers the weighted line. When all but a few feet
of the line has been released, the observer grasps a bight of
the line without wra-pping it around his. hand or otherwise
securing it to his body. The airplane then approaches
against the wind with the weight trailing on the end of the
line and will pick up the card with the message attached
by catching the cord with the weighted line. The line is
then pulled into the airplane and the message is removed.
The ground detail immediately takes up the panel signal.
It is the duty of the observer to assist the pilot in making
an accurate pick-up; he should therefore be alert, as the
airplane approaches the cord, to lengthen or shorten his
hand line so that the weight will strike below the cord. The
observer will take every precaution possible to prevent the
weighted line from striking ground personnel. All person-
72
SIGNAL COMMUNICATION
84^85
nel not engaged in holding poles should stand to one side at
least 50 feet clear of the held poles.
b. More than one attempt may be necessary before the
message is successfully picked up. If an attempt is unsuc-
cessful, the ground detail prepares for another trial. The
panel signal meaning "Pick up message at this point" will
not be displayed until all is ready for the next attempt.
c. All members of the ground detail should watch the ap-
proaching airplane and especially the weight on the end of
the line. Since it is difficult for the pilot to control the
path of the line and weight exactly, the ground men should
be alert to avoid being struck by the weight and also to
prevent the fouling of the line with the poles.
■ 85. Training. — In preparing yearly training programs, pro-
vision should be made where practicable for training in
picking up messages. In order to impress on all personnel
the possibility of the use of this means of signal communi-
cation without standard issue equipment, the ground troops
should be required to improvise entirely the equipment re-
quired, utilizing for the purpose organizational equipment,
personal equipment, and clothing, or articles obtained lo-
cally. For example, two small trees might be used for poles,
stubs or branches being utilized in lieu of nails, undershirts
might serve as panels, handkerchiefs as streamers, an old
rag for a message bag, and unraveled shelter tent ropes for
cord.
73'
86
CHAPTER 4
PIGEON COMMUNICATION
■ 86. Employment. — a. Powers and limitations. — (1) The
employment of homing pigeons as message carriers is based
upon the homing instinct of these birds. A trained homing
pigeon will return to its loft from a distant point, carrying
any light message which has been properly attached to it.
Between the point of release and its loft it is an excellent
and rapid means of signal communication. Its average speed
in clear weather is from a half to three-quarters of a mile
per minute. Snow, fog, rain, or gas interfere with its flight.
It is little vulnerable; the loss in combat due to killed,
wounded, or strayed pigeons is very small. It is a one-way
means of signal communication. Homing pigeons are not
adapted to night flying unless specially trained for that
purpose.
(2) Pigeon communication should be considered as an
emergency means of signal communication, as in the case
of a unit deprived of other means of communication with its
superior unit. (See par. 20c (5) .) Transmission of a mes-
sage by pigeon from a front-line company or battalion to
the next superior unit is indirect and correspondingly slow,
since the loft is usually located out of hostile light-artillery
range.
b. Organisation. — A pigeon company is a part of each field
army. It includes a breeding and training section with
one or more fixed lofts and eight combat sections, each of
which is equipped with two mobile lofts. Fixed lofts are
employed as breeding and training lofts to furnish birds to
mobile lofts. Combat sections are assigned to corps and
elsewhere as needed. From these combat sections individual
mobile lofts may be detached and stationed as far forward
as divisions. The necessary trained personnel accompanies
each loft. (For further details, see Signal Corps Field
Manual.)
3ft
SIGNAL COMMUNICATION
86-87
c. Training and settling pigeons. — Each, time a loft is
moved the pigeons require a period of several days, some-
times as much as 2 weeks, to become accustomed to returning
to the new location. The longer the loft remains in one
position, the greater the distance over which reliable pigeon
communication can be expected. Well-trained pigeons,
thoroughly accustomed to the location of their loft, can cover
a distance of 60 miles without difficulty. (For further de-
tails, see Signal Corps Field Manual.)
d. Mobile lofts. — A mobile loft is stationed conveniently
to the principal command post it serves. A loft may serve
more than one command post. If it is impracticable for a
loft to be located in the immediate vicinity of the command
post, messages received at the loft are transmitted therefrom
by telephone or other means. During movement, continu-
ous pigeon communication may be provided to tactical units
by leapfrogging the lofts, providing there are sufficient lofts
and time for settling them.
e. Pigeon posts. — Pigeon posts are normally provided with
from two to eight birds. The birds are carried in baskets
suitable to the transportation available. Pigeons are as-
signed to tactical units as needed. The personnel for a
pigeon post is furnished by the unit which the post serves.
In battalions and larger units pigeons are usually handled by
message center personnel whose training should include in-
struction in their use.
■ 81. Delivery, Care, and Use of Pigeons. — a. Delivery. —
Arrangements for the delivery of pigeons to pigeon posts of a
division are made by the division signal officer. When de-
livered, they are accompanied by —
(15 Baskets of the proper number and siae for the number
of birds delivered and suitable for the purpose for which
required. (See par. 88.)
(2) Water container for each basket)
(3) Feed.
(4) Message holder attached to each bird.
(5) Gas bag for each basket, if available and required.
(6) Ratproof cage for each basket, if available and re-
quired.
75
87
SIGNAL COMMUNICATION
b. Care. — (1) When, pigeons are received, they should be
placed and kept in a dry place protected from rain, damp-
ness, wind, and drafts. Special care should be taken to
prevent the feathers becoming muddy and caked as the
flight would thereby be greatly retarded. The birds should
be protected from rats, cats, and other animals. If ratproof
cages are supplied, the baskets should be placed In them.
The pigeons should be handled gently and care should be
taken that they are not unnecessarily annoyed or excited.
(2) The message holder which is attached to the leg of
each bird should not be removed at the pigeon post, but it
should be inspected to see that it is loose enough to move
freely on the leg.
(3) The only feed given the birds should be that which is
received with them from the loft. As damp grain is very
injurious to pigeons, care should be taken that this feed is
kept dry. Sicee hunger and tha knowledge that food awaits
them at the home loft are strong influences for quick flight,
it is desirable that pigeons be not fed within 24 hours prior to
release. If, however, it becomes necessary to keep the birds
at the liberating post more than 24 hours, they should be
fed mixed grain twice a day at the rate of a teaspoonful
per pigeon per feeding. When early release of a pigeon can
be foreseen, the last regular feeding should be omitted.
(4) Fresh water should be offered the pigeons every 6
hours, and also 15 or 20 minutes before release when the time
of release can be foreseen.
c. Use. — (1) Maximum time before release. — Pigeons
should not be kept confined away from their loft for a longer
period than 2 days and 3 nights. After the third night, if
replacements are obtainable, they should be released, with a
message informing the loft of the reason and time of release.
If replacements are not obtainable, they may be retained as
long as necessary provided feed is available for them, (See
par. 88o.)
(2) Messages. — (a) Messages to be sent by pigeon are
written on thin sheets of paper. These may be the pigeon
message sheets of the field message book; cigarette papers
may be used in emergencies. The message is folded and
Placed in the message holder attached to the leg of the bird.
76
SIGNAL COMMUNICATION
87-86
As a precaution against failure to reach the loft, each, pigeon
should carry, in addition to the new message, a duplicate of
the next preceding message sent by pigeon from that post.
(b) Pigeon messages containing information of value to
the enemy are normally encoded. (See par. 20c (5).) The
pigeon may fall into the hands of the enemy, thus disclosing
the contents of the message.
■ 88. Transporting Pigeons. — a. Pigeons are delivered to the
pigeon post in one or more of three types of baskets: PG-8,
4-bird capacity; PG-5, 15-bird capacity; or PG-12, 30-bird
capacity.
b. The basket PG-8 is a very small -willow wicker or rattan
basket which is used by forward pigeon posts. As birds
have very little space for movement in this basket they
should not normally be kept in it longer than 48 hours,
c. The baskets PG-5 and PG-12 are made of willow wicker
or rattan, are lined or partly lined with muslin, and are
without interior partitions. They are less confining than
the basket PG-8. Therefore, when they are available, birds
should be placed in them to permit greater freedom.
■ 89. Releasing Pigeons. — To catch the pigeon in its bas-
ket, and to release it, proceed as follows:
o. Fold the message compactly in such a manner as to fit
the message holder and hold the message between the teeth
while catching the bird.
b. Turn the bird so that it faces toward you and force it
gently to the side or end of the basket. (See fig. 2.)
c. With the palm against the wing, place the thumb across
the bird's back and the Angers under the bird's body, catch-
ing its feet between the index and middle fingers as shown
in figure 3.
(f. Remove the bird head first from the basket. If the
basket opening is of sufficient size, use both hands in catch-
ing and removing the bird. Always use both hands in. hold-
ing the bird after removing it from the basket as shown in
figure 4.
e. When holding the bird, always keep its breast firmly
against your body and the hand in the same position as used
181584°— 39 6
7"?
89
SIGNAL COMMUNICATION
Fislpre 2, — Force the bird gently to the side or end of the basket.
Figure 3. — Catch the feet between the index and middle fingers.
in catching it, as shown in figure 5. Hold the bird loosely
and. If it is large, or your fingers short, make no attempt to
hold both wings with the thumb. As long as the bird is
held firmly against the body it cannot escape and any at-
tempt to hold both wings is likely to damage the flight
feathers seriously. Do not transfer the bird from one hand
to the other.
/. With the bird held in the position as described in e
above, extend its leg and hold it by applying pressure at the
knee joint with ends of the index and middle fingers as
shown in figure 5, Remove the upper half of the message
holder which is attached to the bird's leg and insert the
78
SIGNAL COMMUNICATION
89
89
SIGNAL COMMUNICATION
folded message therein. Replace the upper half of the
holder in the lower half,
sr. Always turn the holder so that it rests on the front of
the leg; if on the back of the leg the holder interferes with
the bird walking and holding its legs up under its tail in
flight. See that the holder does not fit tightly but is free
to move on the leg.
h. Extend the arm with the hand holding the bird as in e
above and open the hand.
i. When releasing a bird at night, select an open spot free
of wires, trees, and other obstructions, and give it a gentle
upward toss as the band is opened.
30
90
CHAPTER 5
RADIO COMMUNICATION
Section i, General-
Paragraphs
90-97
II. Operating regulations,
m. Station records
IV. Tactical radio nets
V. Special procedures
98-107
108-lli
112^118
119
Section I
GENERAL
■ 90, Definitions. — The terms, as used in this chapter, are
defined below. For definitions of other terms, see para-
graphs 5 and 13.
a. Break-in operation. — Break-in operation is operation
wherein the receiving operator can interrupt the transmitting
operator at any time.
b. Call sign. — A call sign is a group of letters, or of letters
and numerals, used for station identification.
e. Frequency assignment. — The frequency assignment of a
station is the frequency or frequencies, usually expressed in
kilocycles (kc) or megacycles (mc), at which the station is
authorized to operate. For sets which are calibrated in
channels or tuner settings this assignment is made by assign-
ing channels or tuner settings.
d. Heading. — The heading of a- message is that part which
appears before the text begins. (See JANP.)
e, Intercept station. — An intercept station is a station that
copies enemy radio traffic for the purpose of obtaining in-
formation or friendly traffic for the purpose of supervision.
/. Internet traffic. — Traffic between stations which are not
assigned to the same net is called internet traffic.
g. Linking station, — A linking station is a station used for
the relay of messages from one net to another.
h. Mobile station. — A mobile station is a station that nor-
mally operates from a stationary location but which can be
81
90
SIGNAL COMMUNICATION
rapidly transported to another location. The station may in
some cases be operated while in motion.
i. Number. — The numbers denned below should not be con-
fused with the message center number referred to in chap-
ter 2.
(1) Message serial number. — A message serial number is a
number assigned by an operator to an outgoing message to
facilitate handling and checking of traffic. It is never used
in the abbreviated form message.
(2) Writer's number. — A writer's number is a number
which may be given, a message by the writer and which is a
part of the text.
j. Net call sign. — A net call sign is a call sign used to call
all stations in a net.
k. Position finder station. — A position finder station is a
station containing one or more radio receivers capable of
finding the location from which incoming radio waves are
arriving at the receiver.
I. Radiotelegraph^. — Radiotelegraphy is radio communica-
tion by means of the International Morse Code.
m. Radiotelephony. — Radiotelephony is radio communica-
tion by means of voice signals.
n. Service. — The service of a message consists of the nota-
tions made on a message l>y transmitting and receiving oper-
ators.
o. Signal operation instructions. ,— See paragraph 261.
p. Station log. — A station log is a chronological record of
traffic kept at a station,
ff. Traffic. — Traffic consists of all transmitted and received
messages.
r. Transmission.— A transmission is a complete communi-
cation between stations including all queries, repeat-backs,
and receipts.
s. Trick or watch.— A trick or watch is a tour of duty as
an operator.
t. Vehicular station. — A vehicular station is a station so
installed in a vehicle that it is capable of operation with the
vehicle in motion,
82
SIGNAL COMMUNICATION
91-92
■ 91. Employment, — a. Radio is used as a means of signal
communication between all combat units down to and in-
cluding battalions, squadrons, individual airplanes, and cer-
tain vehicles of mechanized units, for liaison and fire con-
trol, and for the control of forward combat units to include
the company in some situations.
b. Radiotelegraphy is the normal means of radio com-
munication. The International Morse Code is used, for
radio-telegraphy by the Army and Navy. (See par. 127.)
c. Radiotelephony is limited to special uses such as be-
tween airplanes, between airplanes and ground, between ve-
hicles of mechanized units, between ground stations and
vehicles, for artillery fire control and liaison, and for control
of forward combat units.
d. Radio communication within a tactical unit on the
march may be established at prearranged times and places or
between vehicular stations accompanying the units and oper-
ating while actually on the march.
e. Paragraph 245a applies to radio equipment also.
■ 92. Powers and Limitations. — a. The range and quality
of radio communication are, in general, independent of con-
ditions of roads and traffic, and are affected by the nature
of the intervening terrain in a varying degree depending
upon the frequency used. Vehicular sets however are af-
fected by conditions of roads and traffic. Weather condi-
tions may have a serious effect on range and quality. (See
par. 96.)
f>. Radio communication is the most effective means of
signal communication between rapidly moving units when
the maintenance of wire and messenger communication is
impracticable.
e. Radio communication can be readily intercepted by
hostile stations. This disadvantage necessitates the habitual
encoding of messages when transmitted by radio. (See par.
43.)
d. The approximate number, types, and locations of our
radio stations can be determined by hostile position finder
stations. From this information the enemy can estimate the
83
9&-94
SIGNAL COMMUNICATION
disposition and approximate strength of our forces. This
disadvantage of radio communication can be minimized by —
(1) Curtailing the use of radio during the times this in-
formation would be of most value to the enemy.
(2) Establishing dummy stations to cause errors in his
deductions.
e. Hostile radio stations can interfere deliberately with
our radio communication by blocking a single frequency or
band of frequencies and by deception, that is, causing our
stations to accept false or erroneous information and mes-
sages. The effects of interference can be minimized by —
(1) Training radio operators in the strict observance of
radio discipline and radio security,
(2) The use of prearranged signals or groups of letters
preceding each transmission. to identify the station making
the transmission.
(3) Frequent changes and limited use of call signs.
(4) Limiting the number of stations in a net.
■ 93. Radio Nets and Net Control Stations. — a. Nets. — See
also section IV. In order that radio communication may
follow the proper channels of tactical command, the radio
station of a superior unit and the radio stations of the next
subordinate units are grouped together for operation. This
group is called a radio net. To insure a smooth now of
message traffic in a net it should contain not more than five
stations. (See flg. 6.)
o. Net control stations. — The operation of radio nets must
conform to tactical conditions. Stations must move with
the headquarters of their units in order that the net may
serve promptly the will of the commander. Centralized
control and net discipline are therefore required. (See pars.
113 and 114 for further details.)
■ 94. Assignment of Frequencies and Call Signs. — a. Radio
nets must operate on assigned frequencies to prevent inter-
ference with each other. Each radio net is assigned certain
definite frequencies on which to operate. These frequencies
are normally allotted by GHQ and assigned to units through
army, corps, and division headquarters.
b. Call signs are assigned in the same manner as frequen-
cies.
64
SIGNAL COMMUNICATION
94-S6
Figttee 6. — Tactical radio nets.
c. Assignments of call signs and frequencies are issued in
the form of signal operation instructions. (See page 283 and
facing page 284 for examples.)
d. Changes in assignment of call signs and frequencies may
be expected by radio nets in the combat zone. These changes
will be made at intervals which may vary in length from 24
hours to several days and are made for purposes of signal
security.
e. The use of any call sign or frequency not assigned by
higher headquarters is prohibited.
■ 95. Training op Radio Operators. — See TM 2260-5.
■ 96. Location of Stations. — a. The following considerations
are important in the location of radio stations:
(1) Stations should be in quiet localities, protected from
moisture and from enemy fire. The copying of weak signals
requires great concentration by the operator. Therefore,
noise and confusion in the vicinity of stations should be
minimized.
(2) Stations should be placed at a distance from any
source of radio interference. Sources of possible interference
85
96-98
SICNAI COMMUNICATION
are power lines, telegraph and telephone lines, and electrical
equipment of any sort, including nearby radio stations,
E>. Radio waves, especially those of very high frequencies,
may be screened by intervening objects such as high hills,
wooded areas, large structures of reinforced concrete and
steel, and pole lines carrying conductors. To minimize the
effect of such screening, the radio station should have Its
antenna located in the clear and elevated when practicable.
(See par. 92a.)
■ 97. Special Uses of Radio. — a. Radio is used in the mili-
tary service for numerous special purposes, among which
are —
(1) Reception. — (a) Location of enemy radio stations on
land, ships, or aircraft.
(b) Interception of hostile radio traffic.
(c) Interception of friendly radio traffic for supervisory
purposes.
id) Collection of upper air meteorological data from, bal-
loons, airplanes, or airships.
(2) Transmission. — (a) Meteorological information.
<b) Time signals.
(c) Press reports.
id) Propaganda.
b. These special services: are operated and maintained by
the signal troops of the higher units, usually the army,
c. Copying of press reports is a function of the army signal
service which in turn rebroadcasts to the lower units.
d. Meteorological information is normally broadcast at
fixed hours for the information of units concerned.
Section II
OPERATING REGULATIONS
■ 98, General. — a. Technical Regulations. — See paragraph
4a (1).
b. Instruction books. — The technical operation of some
radio sets is covered in instruction books prior to the publi-
cation of Technical Regulations for those sets. When these
instruction books are published, one or more copies are issued
with the sets as parts thereof.
86
SIGNAL COMMUNICATION
99-100
■ 99. Procedure akd Proceduee Signals, — a. Defined. — (1)
Radio procedure is a standardized routine used by radio oper-
ators in the handling of traffic.
(2) Procedure signals are nonsecret, arbitrary signals
which have been adopted to assist operators in handling
traffic in the shortest possible time. Hereinafter the term
procedure signals "Will be used to include the terms procedure
signs and procedure signals defined in JANP.
b. How prescribed. — CI) T& insure a standard operating
procedure or routine for the military and naval services, the
Joint Army and Navy Radiotelegraph and Radiotelephone
Procedure (JANP), approved by the Secretaries of War and
Navy, is issued for the guidance of the Army and Navy per-
sonnel concerned. The JANP is distributed to the Army by
The Adjutant General,
(2) Strict compliance with the JANP and any supple-
mental regulations relative to operating procedure insures
the accurate and rapid handling of traffic with minimum
transmissions. Every radio operator must have a thorough
knowledge of the correct procedure to use in any particular
case. Deviation from authorized procedure usually results in
delaying traffic and is prohibited. Certain short cuts in pro-
cedure to speed up traffic under special conditions are spe-
cifically authorized in the JANP.
c. For special procedures, see section V.
■ 100. Codes attd Ciphers. — Several types of codes and ci-
phers are used for encoding messages. (See pars. 5a, 47,
and 48.) A partial list of the various message codes and
ciphers with their indicators and the number of characters
comprising each code group is shown below. Indicators of
codes authorized for training include the letter T before
the number. For example, PFC-T1 is the indicator for the
training issue of the Division Field Code. Similarly, those
authorized for use in maneuvers include the letter M. For
example, AGL-M1 Is the Indicator for the maneuver issue
of the Air-Ground Liaison Code,
87
100-102
SIGNAL COMMUNICATION
Name of code or cipher
Indicator
Number of
characters
per group
The "War Department Telegraph
Code.
The Division Field Code-
The Fire-Control Code
Tho Air-Groond Liaison Code
The Meteorological Oode
Cipher device M-94
WTC,
T>F0, followed by a number
FCC, followed by a number
AGL, followed by a number
M, followed by two letters
OD
4, 5, 6, or 7
5
4
2
3
■ 101, Transmitting Rules. — a. An operator will listen on
the transmitting frequency assigned his station before mak-
ing any call or other transmission. If there are other sta-
tions working on the frequency he will not interrupt com-
munication unless such interruption is warranted by the
class of his traffic. (See JANP.)
&. All transmissions must be as short and concise as pos-
sible. No superfluous calls or signals of any kind will be
sent. An operator may test his transmitting set before the
first transmission by sending a few "V's" followed by his
own station call sign.
c. Messages and transmissions must be sent at a speed
which will allow the receiving stations to copy them on the
first transmission. Thus no transmissions should be faster
than the slowest operator in a net can receive them.
d. Particular care is necessary that all call signs are made
slowly and distinctly.
e. The procedure sign for "wait" is used when an imme-
diate answer cannot be given,
/. An "end of message" sign will always be used.
■ 102, Transmissions. — a. A radio station will transmit only
those messages authorized by competent authority. All
transmissions and messages handled will be considered as
official. (See pars. 27J> and 35a (4).)
b. At times there is need for certain inquiries, instruc-
tions, and information in connection with the handling of
traffic. In general, this need is adequately met by the pre-
scribed procedure signals. When procedure signals cannot
be used a message will be employed. The exchange of trans-
missions in other than authorized form is prohibited.
88
SIGNAL COMMUNICATION
106-104
c. The chief operator or station chief of a station has
full authority to authorize the transmission of messages
relating to the signal service. Such messages will be signed
with the call sign of the station of origin, and will be in an
approved code,
d. Every operator will read through the text of each mes-
sage filed to ascertain that each word or the individual let-
ters of each code group are clear and unmistakable. If
there is any doubt about any of the words or letters he will
have them verified,
■ 103. Time Entries and the Radio Day. — Unless otherwise
specified by higher authority —
a. Time entries on the station records are made in the
time of the zone in which the station is located.
&. Transmissions involving the specifying of time (time
broadcasts, transmissions as to the time a station will call
another station or return to a net, etc) likewise use the
time of the zone in which the station is located.
c. The radio day is the 24 -hour period covered by a com-
plete set of station records. It commences at midnight of
the time zone in which the station is located, and ends at
the following midnight of the same zone. All station rec-
ords of all stations in the net will be opened and closed in
accordance with the above -mentioned rule.
■ 104. Cooperation With the Message Center. — a. The
message center at each headquarters is the agency charged
with the receipt, transmission, and delivery of messages.
(See ch. 2.) The message center is also charged with the
encoding and decoding of messages when reauired. It is
therefore essential for radio station chiefs to keep the mes-
sage eenter informed at all times of the stations actually
operating in the net and of traffic conditions with reference
to any delay time that might occur to messages routed by
radio.
&. Any messages that cannot be sent without delay should
be returned to the message center for routing by other
means. Failure by radio station personnel to cooperate fully
with the message center or other traffic routing agencies that
may be prescribed will result in serious delays in the delivery
89
104^107
SIGNAL COMMUNICATION
of messages and in much, useless code work by the message
center personnel.
■ 105. Reception, — a. All received messages are copied at
the radio station in duplicate. Messages are copied on the
typewriter or by hand using the system of lettering described
in. paragraph 42. When copied by hand, five code groups
will constitute a line. In using the typewriter, five or ten
code groups will constitute a line.
b. See paragraphs 28a and 35b for the disposition of the
original and the duplicate copy of incoming messages. To
delay original copies of messages for recopying or extracting
data for station records is prohibited.
c. See paragraphs 30 and 35c for the disposition of the
original and the duplicate copy of relay messages.
■ 106. Operator's Personal Sign. — Each operator is identi-
fied by a personal sign of one or two letters. No two opera-
tors in the same station will use the same sign. The per-
sonal sign of an operator is never transmitted but is used
only in connection with the keeping of station records.
■ 107. Servicing of Messages. — a. Every message is serviced
by the transmitting operator and the receiving operator
upon the completion of its transmission. The transmission
of a message requiring a receipt or a repeat back is not con-
sidered complete until such receipt or repeat back is received
by the transmitting operator.
b. The operator's service is written in at the bottom of
the message. Many operators perform this service with one
hand while operating the key with the other. This service
consists of the time transmission of the message is com-
pleted, and the personal sign of the operator. For example,
956A JM.
c. A transmitted message must show the station to which
it was sent and a received message must show the station
from which it was received. In any case where this infor-
mation is absent from the heading of the message the oper-
ator's service will include it.
90
SIGNAL COMMUNICATION
108
Section in
STATION RECORDS
■ 108. Operator's Number Sheet. — Stations that are re-
quired by the JANP to use message serial numbers on mes-
sages will keep a record of these numbers in the following
manner:
a. On the completion of the transmission or reception of a
normal form message, each key operator concerned will draw
a line through the number of the message sent or received, on
the number sheet, in the column assigned to the other station
involved and enter the time of receipt and his personal sign
in the blank column to the right.
b. The following example fndicates a completed extract
of a satisfactory number sheet for recording message serial
numbers :
OPERATOR'S NUMBER SHEET
Check off both sent and received numbers immediately and
enter, time and personal sign. Numbers must be exchanged
nightly at closing hour. Receiving and sending operators
will be held responsible for correct records of numbers.
STATION LA CIRCUIT OR NET 9TH INF DATE 6 JUNE
Bent
HGAILC.
'tOS&AiJY.
1MAIJY
RSCETVED
mAjLC.
900AILC.
91SA/LC
miAUY
OA
Sent
RECEIVE!)
1
8MA/LC..
?
OtlA/LC
i
%
B
miAILC
1
9
0
wsiAjjy
r
2
»
4
5
B
7
OlOAJLC.
10I0AILC
1040AIJY
11MA/JY
UUAIJY
Sent
91
109
SIGNAL COMMUNICATION
■ 109. Station Log. — a. General. — (1) A station log in con-
junction with the number sheet and the file of transmitted and
received messages forms a complete record of events and
operating conditions which occur during a radio day at a
station.
(2) 'Hie amount of detail that should appear upon the log
varies according to the number of operators on duty at the
station, and the state of training of the operators.
(3) In any case the keeping of the log should not operate
to delay traffic.
(4) Signal and communication officers are authorized to
prescribe the amount of detail that they require on the logs
of their stations but the following essential elements with
time entry for each will be included:
(a) Operators on duty.
(b) Opening and closing of stations.
(c) Causes of delays in traffic.
«£) Frequency adjustments and changes,
(e) Unusual occurrences such as procedure violations, veri-
fications, etc.
(5) During the Initial training phases the log should in-
clude all signals heard or transmitted, thus serving as a
detailed check on operating procedures. As training pro-
gresses the amount of detail required can be gradually
reduced to the essential elements listed in (4) aibove. ■
b. Form and example. — (1) Training form. — The following
is a satisfactory station log form for use during the initial
training period and for stations having a senior (key) and a
junior (log) operator. A forai of this kind is desirable when
actual transmissions are to be logged in detail.
92
SIGNAL COMMUWrCATrOM
109
Station Log
Date 19 Net Sheet No.
Station call Net call Station opened M
Senior operator Junior operator
Tune
To
From
Traffic
(2) Example of log, — During the later training period and
in actual field operations a combination form having the
operator's number sheet printed on one side and a log
printed on the reverse side is more satisfactory. The opera-
tor merely turns his number sheet over and makes the log
entry on the back thereof as the events requiring a log
entry occur. The following Is an example including entries
of such a form in common use at fixed stations. This form
is printed on the reverse side of the operator's number sheet
shown in paragraph 108.
Log
Enter opening and closing times, frequencies and frequency
changes, traffic delays, and any incidents or conditions affect-
ing circuit efficiency.
STATION LA CIRCUIT OR NET 9TH INF DATE 6 JUNE
Time
Operator
Remarks
SOtA
SIS
911
9fi
950
1030
10SS
mo
mo
usi
ssop
LC/JY
STATION OPENED AT CEDARFALLS flOO KC.
MS AND OA IN NET.
CLOSED STATION FOR MOVE.
REOPENED AT MILLBROOK OA OUT.
OA IN NET
…[truncated]