Jessie Fothergill.

The Encyclopædia Britannica : a dictionary of arts, sciences, literature and general information (Volume 32) online

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the adoption of the buzzer telephone as a standard army instru-
ment and the employment of the motor cyclist as a message car-
rier placed two new methods of intercommunication at the
disposal of the signal officer. The outbreak of the World War in



SIGNAL SERVICE, ARMY



487



Aug. 1914 found the Expeditionary Force equipped with a signal
service controlled by a director of signals on the general staff at
G.H.Q. This service included a signal unit at G.H.Q., a lines-of-
comraunication signal company, and a signal company with each
corps and each division. Artillery intercommunication was, how-
ever, entirely a separate matter for which that arm itself was
solely responsible. So also, was intercommunication inside the
infantry unit; and the absence of a chain of command within the
signal service itself (each unit commander being responsible only
to his own general staff) caused a looseness of organization which
soon showed itself to be a grave defect. The means of intercom-
munication employed were those already mentioned, viz., tele-
graph, telephone, flag, lamp and heliograph, with the addition of
wireless telegraphy, which was, however, at this time adopted
only for the special requirements of the far-ranging cavalry divi-
sion, and consisted only of one lorry and a few wagon and pack
stations, all of rotary spark type. (The power of the stations was
3, 1-5, and 0-5 K.W. respectively; the range, when working to
stations of similar type, 100, 80 and 30 miles.)

The signal organization summarized above proved adequate to
deal with the mobile conditions of the first few months of the
war. These early days were specially notable for the triumph of
the motor cyclist. Telegraph and telephone, visual and orderlies,
and mounted liaison officers also played useful parts, and it was
not until position warfare set in in the winter of 1914-5 that fur-
ther changes were found to be required. Then, however, the
desire for, and the possibility of collecting, a greater quantity of
more exact information (especially for artillery observation) led
to a considerable increase in the complexity of the army signal
organization. To the exigencies of position warfare may be attrib-
uted almost all the evolution in signal implements and signal
organization which marked the course of the war. The chief
alteration in signal policy, on the other hand, was brought about
not so much by position warfare as by the resumption of semi-
mobile and mobile warfare which took place to a slight degree in
1916, toa slightly greater extent in 1917, and completely in 1918.

The principal result of " stabilization " was naturally an im-
mense increase in the number and weight of the guns employed.
Both for offensive and defensive purposes massed artillery be-
came the weapon of paramount importance, and this had two
principal effects on the forward signal service. The fire of the
large number of guns employed could not be effectively directed
without a greater measure of intercommunication; while at the
same time, intercommunication in the region subject to heavy
gunfire became more and more precarious.

The extra intercommunication required was supplied by a
rapid increase in the number of telephones in use at observation
posts and at artillery headquarters. The need for intimate liaison
between infantry and guns led to a similar increase at infantry
headquarters.

The magneto telephone came into use for the first time forward
of corps headquarters, and, once the superior convenience and
efficiency of the instrument were recognized, the demands for its
installation increased so rapidly as to tax the signal service to its
uttermost capacity. A new danger at once arose and threatened
to wreck the whole intercommunication service. The tendency
was to concentrate all available energies on the installation of
telephones and the laying and maintenance of telephone lines.
All other means of signalling lost their proper proportion, and an
inefficient telephone service was soon in a fair way to become the
only means of intercommunication throughout the whole army.
Such an undesirable result was only prevented by the incidental
troubles arising from the indiscriminate laying of lines. In effect,
it was the " overhearing " menace, which will be referred to
later, that, together with the prevalence of induction trouble and
the difficulty of making " safe " the forward lines, proved to the
signal service and to the commanders it served that it was unwise
to stake everything upon one method of intercommunication.

The difficulty of maintenance of forward intercommunication
was overcome partly by the adoption first of shallow and subse-
quently of deep buried cable; partly by the evolution of various
new alternative methods of signalling; partly by the perfection



and adaptation of methods which had temporarily fallen into
disrepute under the new conditions.

In 1915, cables were buried 2 or 3 ft. deep and by this means
temporary immunity from shellfire was gained; in 1916, the
general adoption of the 6-ft. bury (while it saddled the signal
service with endless labour problems) successfully solved the
difficulty of the maintenance of an efficient forward telephone and
telegraph system. One inevitable consequence of the adoption
of the " bury " was the concentration of the forward lines into a
few main routes, thus paving the way for the great reform in
policy which was later brought about under the pressure of rather
different circumstances.

The induction which resulted from the collection of 20 to 100
circuits in these main corps and divisional routes was reduced to
a slight extent by the general substitution of the sounder for the
vibrator in forward units 1 and by the elimination of the buzzer
as a general means of intercommunication. It was later almost
entirely overcome by the adoption of metallic circuits of twisted
cable 2 for all forward lines.

Mention should be made of the alternative methods of sig-
nalling which underwent their first main period of evolution in
1915. In 1914, the weight and accuracy of modern artillery fire
had caused visual signalling to fall into disrepute as being too
dangerous. It was soon found, however, that the lines which
were at that time the only general alternative to forward visual
signalling, were also untrustworthy, and that salvation lay in
employing as many alternative means as possible and therefore
in improving all available methods as well as evolving new ones.
Visual was rehabilitated by the invention of the inconspicuous
signalling disc and shutter, by the general adoption of " D.D.
D.D." working (signalling from front to rear without reply) and
by the adoption of the efficient electric signalling lamp in place
of the more conspicuous and noisy Begbie oil lamp which was the
standard equipment at the outbreak of war. At the same time
the use of pigeons as message-carrying agencies was revived, and
wireless telegraphy began to be adapted to forward work. The
former were first used by the Intelligence Corps towards the end
of 1914, when the British were operating in a district noted for
its pigeon fanciers. From this small beginning grew a service
which at the Armistice numbered over 20,000 pigeons, while no
less than 90,000 men of all arms had been trained to handle the
birds. Lofts were kept usually on a line passing about through
divisional- headquarters and pigeons were forwarded by motor
cyclist and taken into the trenches by selected pigeoneers.
Here they remained until required for use or until 48 hours had
elapsed, when they were released with or without messages.

Wireless telegraphy for the forward area was first attempted in
the summer of 1915, when experiments were carried out which
resulted in the standardization of two types of set, the I2o-watt
(Wilson) and the $o-watt (British field) set. The former was
intended for work at divisional and corps headquarters and
consisted of separate transmitting and receiving apparatus. The
spark transmitter received its energy from a 26-volt accumulator
through a small motor-driven interrupter fitted in the set itself;
its original complement was a crystal receiver specially designed
for the short waves (350, 450, and 550 metres) on which the for-
ward sets were obliged to work. The 5o-watt set, on the other
hand, was a combined transmitter and receiver, the transmitting

1 The two telegraph instruments, the sounder and the vibrator,
are worked on entirely different principles. In the former case the
currents used rise to their full value very rapidly and then remain
steady a comparatively long time. On the vibrator system, on the
other hand, the currents used are constantly altering in value and
even changing in direction, the vibrations being at an audible rate
of frequency (several hundred per second). It is these latter rapidly
alternating currents which set up rapidly alternating EMF in the
earth surrounding the conductor and provide the ideal conditions
for overhearing at a considerable distance. A buzzer is a particular
type of instrument using " vibrating " or " alternating " current.

2 In a telegraph circuit consisting of two wires laid side by side,
the electromotive force set up around one conductor will be neu-
tralized by that set up around the other in which the current is
travelling in the opposite direction. The most efficient disposition
of such neutralizing cables is naturally that where the two halves
are most intimately interturned, as in twisted cable.



488



SIGNAL SERVICE, ARMY



portion of which was energized by the current from a lo-volt
accumulator. It was intended for work in posts close to the front
line and at brigade and battalion headquarters and the complete
station with its two i s-foot masts could be carried by a party of
three men. Both types of set fulfilled their original purpose
admirably. They remained the standard wireless sets for forward
infantry command intercommunication purposes throughout the
war, and have only gradually been superseded by the continuous-
wave wireless sets which are now the standard sets for practically
all purposes.

Other wireless sets which were evolved during the war, which
owed their invention to the same necessity for indestructible and
invisible alternative means of forward intercommunication, were
the loop wireless sets. These were sets of short fixed wave-length
(66 and 80 metres respectively) which were arranged in two
complementary installations a " forward " and a " rear " sta-
tion to each set. The forward station was distinguished by the
possession of a rectangular aerial of folding tubing which could
be erected wholly below the surface of the ground in a deep
trench or in a dugout, thus rendering the station invisible and
often invulnerable. The rear station had a short wire aerial,
much of the type used with the standard "British field" (50-
watt) set. It was intended, as its name suggests, for work at
places not in the direct observation of the enemy. These sets
with slight modifications, remain in use at the present day for
intercommunication within the infantry battalion.

At least as important as this evolution of alternative methods
was the consolidation and reorganization of the signal service
which took place during the years of position warfare.

For the understanding of the present organization of an army
signal service some account of the effect of the interaction be-
tween the requirements of the general staff and the unfamiliar
war conditions experienced in the years 1914-7 is essential.
Whereas in the pre-war organization of the signal service the
ruling consideration was mobility, a military situation arose
within six months of the declaration of war, and continued for
three years, in which extended movement was the exception and
not the rule. The effect on the signal service was a multiplication
of the calls for intercommunication made upon it and at the same
time an increase in the unreliability of all means of forward sig-
nalling. Work in the danger zone had usually to be done not
once but many times; duplication of routes forward, first of bri-
gade, and then of divisional headquarters, became essential. At
the same time, the demands of the staffs, of the unit commanders,
and especially of the artillery, increased manifold.

An establishment adequate to the demands of mobile warfare
could not possibly cope with those of position warfare. The small
degree of supervision and absence of coordination, due to the
practical autonomy of the signal service within each formation,
which had been recognized as drawbacks in the manoeuvre war-
fare of 1914, became impossible obstacles to efficiency in 1915.

The first reforms which enabled order to be wrought out of the
chaos into which forward signals were in danger of falling were
(i) the vesting of the control of all forward signals in the hands
of the divisional signal company commander and (2) the assump-
tion by the signal service of responsibility for, and a measure of
control over, artillery signals. By this means it proved possible
towards the end of 1915 to eliminate unnecessary lines and to
insist on the reeling-up of derelict cables. At the same time steps
were taken to supplement the obviously inadequate personnel.

The original signal service units of the British Expeditionary
Force of 1914 had consisted essentially of (a) the personnel to
man one or at most two headquarters offices; (6) sufficient cable
or airline detachments to lay one main route to all subordinate
formations or units then considered to be entitled to telephone or
telegraph; and (c) a few despatch riders, orderlies, and visual
signallers. This establishment only just sufficed for the skeleton
intercommunication system required in a mobile army, and
neither office staff, line-building detachments, nor orderlies, were
sufficient to man the greatly swollen system of position warfare.
Reinforcements were essential, and not only reinforcements but
radical reorganization as well. Much of the personnel required



was for the maintenance of heavily shelled, long divisional and
corps lines through the danger area. If these routes were to be
efficiently maintained and circuits allotted with due regard to
the relative urgency of individual requirements, the men man-
ning them must remain at their posts irrespective of divisional
moves. This meant the formation of pools of area-maintenance
personnel and units at corps or army headquarters and the crea-
tion of these pools was one of the main features of signal reorgan-
ization during the position-warfare period. Individual increases
to the mobile portions of units also took place, corresponding to
changes in signal methods (all in the direction of increased com-
plexity) or alterations in procedure (e.g. the assumption of re-
sponsibility for artillery and machine-gun signals) which applied
equally in position and in mobile warfare.

The increases in the strength of signal units during the war are
indicated by the figures in the annexed table, which gives the
strength of the signal personnel in an army of two corps, each of
three divisions, in 1914 (when the only equivalent of an army signal
company was the G.H.Q. signal company) and in 1918, respectively.

Strength, 1914, at Mobilization.







Each




Total


Unit


Off


Other
Ranks


Off


Other
Ranks


G.H.Q. signal company .
Two! army corps H.Q. com


5


75


5


75


panies ....


4


63


8


126


5 airline sections


i


57


5


285


8 cable sections.


i


35


8


280


6 divisional signal companies


5


157


30


942


Total personnel






,S6


1708



Strength at Armistice, iQi8.



Unit


Each


Total


Off


Other
Ranks


Off


Other
Ranks


One army signal company


IS


340


15


34


2 cable sections .


i


34


2


68


3 airline sections .


i


43


3


129


8 area signal detachments .


i


13


8


104


One signal construction com-










pany
One light railway signal com-


3


"3


3


"3


pany


i


61


i


61


9 army, field artillery bri-










gade sig. sub-sections


i


'9


9


171


17 heavy artillery group sig.










sub-sections


i


28


'7


476


Two corps signal companies .


6


105


12


210


4 airline sections .


I


43


4


172


4 cable sections .


I


34


4


136


Six divisional signal compan-










ies


15


400


90


2400


Total personnel






1 68


4380



While the above description applies principally to the evolu-
tion of organization in the general signal service, some special
mention of the alterations which took place in wireless units is
necessary, particularly since wireless telegraphy will in all prob-
ability play a more dominant part in the intercommunication
service of the army of the future. The few wireless sets which
were in use in the British Expeditionary Force at the outbreak of
war were manned by personnel who were all incorporated in a
single " wireless section " which shortly became a " wireless
company." The first great increase in the value of army wireless
came with its application to intelligence purposes, originally for
the simple interception of enemy wireless messages, and then also
for the location of enemy wireless sets whether in the field, at sea,
or in the air. For this latter use of wireless alone, " position
finding " many special sets were devised and a numerous per-
sonnel collected in special intelligence wireless units.

Next, the invention and perfection of the portable " trench "
wireless sets in 1915 and 1916 created a further demand for wire-
less personnel and increased the already swollen establishment of
the central " wireless company." The result was a measure of
devolution and the formation of an army wireless company in
each army. The commanding officer of this unit acted as staff
officer for wireless to the chief signal officer of the army, and was






SIGNAL SERVICE, ARMY



489



responsible for the organization and practice of wireless within
the limits of the army.

Yet another direction in which wireless personnel found em-
ployment was in the detection and prevention of the indiscre-
tions which, in 1916 particularly, enabled the enemy to glean
important information by listening to the traffic over the British
telephone system. It was in 1915 that this menace first became
important and in the following year " overhearing " became so
serious that the forward telephone service was stultified. Many
important results followed, directly, or incidentally. Of these
may be mentioned:

(1) The general adoption of closed metallic circuits everywhere
within 3,000 yd. of the front line.

(2) Alterations in the system of identification calls.

(3) The replacement of the buzzer telephone by the fullerphone
in the forward area.

(4) The invention of the screening buzzer, a powerful vibrator
used for drowning all sounds carried forward by induction from the
front line.

(5) The invention and perfection of the 3-valve listening sets and
the formation of detachments of the army wireless companies to
work them. 1

(6) The growth of an organization for the interception of speech
on enemy lines and the policing of our own telephone system.

(7) The application of earth induction telegraphy to signalling
which resulted in the invention and evolution of the power buzzer.

(8) The increased employment of alternative methods of sig-
nalling (visual, wireless, etc.) so obviously liable to overhearing or
overseeing that they were used with caution.

It is difficult to decide which of the many results was the most
important, but perhaps the most interesting from the present
point of view was the evolution of the power buzzer. This was a
powerful vibrator worked by the current from a lo-volt accumu-
lator, and connected to inconspicuous earths of insulated wire
which could, if necessary, be buried 6 ft. deep with little labour.
It occupied a place in position-warfare signals for which no other
instrument, except perhaps the loop sets which lately more or
less superseded it, was suitable. Detachments of troops isolated
by the enemy could send out code signals which could be picked
up by listening sets, themselves inconspicuous, at ranges up to

ccc

EE




Earth

Earth Co Va/n Interval Intervatve . Valve to Phone

Transformer Transformer



is



tint I.




FIG. i.

3,000 yd. On several occasions of importance these sets remained
the only means of communication with and from units that had
advanced rapidly in attack, or become isolated in defence.

The diagrams in fig. I show the principles of the power buzzer
amplifier system. The transmitter (a) is a powerful buzzer taking its
current from a lo-volt accumulator. When the Morse key is pressed,

1 The early overhearing experiments were made with ordinary
telephone receivers and results, while they pointed out the danger,
were not very satisfactory. In the German, French and British
armies, it was the discovery of the possibility of using the new
3-electrode valves] for magnifying extremely small changes in
electric potential which at the same time raised the " overhear-
ing " menace to its greatest pitch and caused the development of
large branches of " Intelligence " and Signals to deal with this new
branch of scientific warfare. The valves were used in receiving cir-
cuits both as detectors and amplifiers and revolutionized both tele-
phony and wireless telegraphy.



a current from the lo-volt battery flows through the key to the
upper contact, across to the lower contact, along the armature,
thence along the primary coil, and back to the battery. The cur-
rent magnetizes the coil which attracts the armature, thus break-
ing the contact, and allowing the armature to fly back and remake
contact, etc. Each time the primary current is thus completed and
broken, currents in the opposite direction are induced in the second-
ary coil and are passed to earth through shut lengths of cable and
earthpins. Condensers, as shown, are connected across the break to
reduce the sparking to a minimum.

To obtain the best results in two-way working a three-valve
amplifier (6) is employed. The currents, received on similar earths,
pass through the primary circuit, are induced into the secondary
of the earth-to-valve transformer which is connected to the grid
and, through a single dry cell, to the filament of the first valve.
The amplified signal from the first valve passes through the second
and third valves and, finally, the three-amplified signal passes
through a valve to telephone transformer with ordinary wireless
receivers in series with the primary winding.

With all these developments, and especially with the rapid
increase in the number of listening sets, the wireless service, as a
separate entity, was becoming unwieldy, and its absorption into
the general signal service organization was essential to its most
efficient administration. In 1917 and 1918, therefore, the army
wireless companies were broken up, the section which had com-
posed them being allotted to the divisional, corps, and army sig-
nal companies, according as they were equipped with portable
trench sets, Wilson and listening sets, or the larger and more
powerful Crossley motor sets used for supervisory and tactical
work at army headquarters. In this form wireless organization
survived the war.

The only change of moment in army wireless after this time
was the application of the continuous wave system to army use.
The early experimental sets made their appearance in 1917, but
for some months they proved to be too delicate and untrustwor-
thy for the work under the hard conditions of active service.
Gradually, however, technical difficulties were overcome and more
robust types of instrument devised. Before the end of position
warfare, portable 3o-watt continuous wave sets of about the
size and portability of the so-watt spark sets, but with forward
aerials only 4 ft. high and a normal range of 1 2 m. were doing good
work with heavy artillery observation stations. The Armistice
in Nov. 1918 found continuous wave wireless still chiefly confined
to the artillery, but new and more powerful sets had already been
devised and tested. Since that date, spark wireless has been
entirely ousted from its former position except for the short-
range loop sets the successors of the power buzzer which are
retained for work within the battalion and similar small units
working in the immediate vicinity of the front line. There seems
little doubt that in the future development of army signalling,


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Online LibraryJessie FothergillThe Encyclopædia Britannica : a dictionary of arts, sciences, literature and general information (Volume 32) → online text (page 182 of 459)