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1911 Encyclopedia Britannica

Army Signal Service

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"ARMY SIGNAL SERVICE ( see 25.71). - In the ten years that elapsed between the Russo-Japanese War of 1904-5 and the outbreak of the World War in 1914, evolution in military signalling was rapid, both as regards organization and as regards instruments employed. The old principle of deliberate crudity of means, based on the idea that no refined instruments could be relied upon to survive the rough conditions of war employment, was giving way to a sense of the great possibilities opened up by modern science as applied to army signalling, while, in tactics, the ever-increasing tendency towards articulation of forces and distribution in depth was forcing the problems of liaison more and more into the foreground. But such evolution as there was in the period 1904-14 was naturally slight indeed compared with that which took place during the World War, in which stabilized conditions of warfare and the concentration of the scientific talents of all belligerent countries upon war needs produced results, both upon the army signal system and its instruments, that amounted to a revolution in the practice of war and, moreover, must affect profoundly the methods of intercourse between civilized nations in peace.

In the following article an account is given of the organization, working principles, and instruments of the signal service of the British army in the World War, and of some of the more notable features of signal practice in other armies.

(1) Definition and Duties. - The signal (intercommunication) service of a modern army is responsible for the maintenance of efficient intercommunication between all branches, departments, formations, and units of the army. Intercommunication within units, other than signal units, is usually provided by means of regimental signallers, but the officers of the signal service exercise supervisory control here also. The signal service bears the same relation to the army of which it forms a part as does the nervous system to the human body. Its principal duties are: (a) The transmission of information from the front to unit commanders and to the headquarters of formations.

(b) The transmission of orders from commanders to their subordinates.

(c) The maintenance of efficient liaison between infantry and other arms (such as artillery, air force, tanks, etc.) and between neighbouring formations.

For the efficient working of an army, means of intercom munication must be swift, certain, and, under the circumstances of modern war, varied. The system must be essentially simple and standardized to the greatest possible extent, yet capable of considerable expansion at short notice, and of modification to meet the most diverse conditions of warfare. Organization and working schemes must be elastic, and types of signal instruments must be devised to cope with all special sets of conditions that have been experienced or can be foreseen.

(2) British Army System. - Until the application of electricity to the long-distance transmission of messages, the intercommunication of armies was carried out mainly by means of visual appliances or by the use of message carriers. Liaison officers and orderlies have been used from the very earliest times; the arrow was frequently employed in mediaeval times for the transmission of information into and out of besieged towns; the pigeon was used with success, notably in the wars of the Netherlands against Spain; permanent lines of semaphore communication (masts with movable arms) were employed both by the French and the British during the Napoleonic Wars. Later, the invention of the Morse code and the adaptation of the semaphore principle to field signals led to the general employment of flags, lamps and, later, of the heliograph. The field telegraph made its appearance in the middle of the 19th century, and in the last years of the century the field telephone came into use. Lastly, in the Russo-Japanese War of 1904-5 wireless telegraphy came on the scene.

In 1911 the British " Signal Service " was constituted as a distinct branch of the Royal Engineers. At about the same time, the adoption of the buzzer telephone as a standard army instru ment and the employment of the motor cyclist as a message carrier placed two new methods of intercommunication at the disposal of the signal officer. The outbreak of the World War in 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-ofcommunication signal company, and a signal company with each corps and each division. Artillery intercommunication was, however, 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 intercommunication employed were those already mentioned, viz., telegraph, 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 division, 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, So 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 further 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 maybe attributed 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 semimobile and mobile warfare which took place to a slight degree in 1916, to a slightly greater extent in 1 9 17, and completely in 1918.

The principal result of " stabilization " was naturally an immense increase in the number and weight of the guns employed. Both for offensive and defensive purposes massed artillery became 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 subsequently of deep buried cable; partly by the evolution of various new alteruative 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 zoo 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 signalling 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 120-watt (Wilson) and the 50-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 (35 o, 450, and 5 5 metres) on which the forward sets were obliged to work. The 50-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 neutralized 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.

portion of which was energized by the current from a ro-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 15-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 continuouswave 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 " station 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 " (50watt) 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 between 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 signalling. Work in the danger zone had usually to be done not once but many times; duplication of routes forward, first of brigade, 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 warfare 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 - (1) the vesting of the control of all forward signals in the hands of the divisional signal company commander and (2) the assumption 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; (b ) 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 manning 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 creation of these pools was one of the main features of signal reorganization 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 complexity) or alterations in procedure (e.g. the assumption of responsibility 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.

Unit

Each Total

Off

Other

Ranks Off

Other

Ranks

G.H.Q. signal company. .

5

75 5

75

Two; army corps H.Q. com-

panies .

4

63 8

126

5 airline sections

1

57 5

285

8 cable sections... .

1

35

280

6 divisional signal companies.

5

157 30

942

Total personnel. .

56

1708

Unit

Each

I Total

Off

Other

Ranks

Off

Other

Ranks

One army signal company

15

340

15

340

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

3

113

3

113

One light railway signal com-

pany

1

61

1

61

9 army, field artillery bri-

gade sig. sub-sections

I

19

9

171

17 heavy artillery group sig.

sub-sections

I

28

17

476

Two corps signal companies .

6

105

12

210

4 airline sections. .

I

43

4

172

4 cable sections .

1

34

4

136

Six divisional signal compan-

ies. .. .. .

15

400

90

2400

Total personnel .

168

4380

Strength, 1914, at Mobilization. Strength at Armistice, 1918. While the above description applies principally to the evolution 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 probability 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 personnel 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 wireless 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 responsible for the organization and practice of wireless within the limits of the army.

Yet another direction in which wireless personnel found employment was in the detection and prevention of the indiscretions 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: (I) 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.' (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 signalling (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 to-volt accumulator, 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 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 to-volt accumulator. When the Morse key is pressed, ' 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 " overhearing " 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 circuits both as detectors and amplifiers and revolutionized both telephony and wireless telegraphy.

a current from the Io.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 current magnetizes the coil which attracts the armature, thus breaking 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 secondary 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 (b ) 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 composed them being allotted to the divisional, corps, and army signal 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 untrustworthy 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 30-watt continuous wave sets of about thesize and portability of the 50-watt spark sets, but with forward aerials only 4 ft. high and a normal range of 12 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 shortrange 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, continuous wave wireless is likely to play an all-important part.

While the chief characteristic of the earlier position-warfare period was the evolution of signal implements and the adaptation of signal organization to stationary tactics, it was in the great battles of 1916 and 1917 that signal policy began to crystallize in very definite shape. The first result of the stabilization of the situation was the running forward of lines in all directions to serve the multifarious units which now for the first time made good their claims to telephone communication. Magneto and buzzer telephones and magneto, buzzer, and combined exchanges made their appearance in all formations from brigade rearwards, and buzzer telephones and exchanges were issued to battalions and batteries. The lines to serve these telephones and exchanges had in many cases to be duplicated and even triplicated, and a festoon of lines, converging from front to rear, or stretched transversely and at all angles across the front, hampered move ment and defied the utmost efforts of the signal personnel whose business it was to maintain them. The necessity for economizing signal personnel and for the protection of lines alike tended to bring about two reforms. On the one hand, control was vested, in the signal officers of superior formations; on the other hand, by their orders, all circuits were concentrated into a certain limited number of well-defined main routes.

The first of these reforms in point both of importance and of time was the rearward movement of the centre of gravity of the /nterva/ve Trons, former /ntervolve Transformer I.P ' 1.5 ' .Valve to Phone Transformer command of forward signals from the uncontrolled battalion, through brigade, division, and corps, to army. Concurrently with this, the commanders of signal units became staff officers - i.e., representatives of the command itself - instead of simple executants.' In the meantime, the idea of the central signal route in each formation having been launched, it was natural that other means of signalling should at once tend to concentrate along these routes, with their protected test-points and signal offices. Economy and greater trustworthiness at once followed, and in the battle of the Somme, 1916, when the British army first carried out a great offensive from prepared positions, the central signal route, running from front to rear of each divisional sector and reinforced with all possible means of intercommunication, was attempted as a definite policy. The line system was carried forward in 6-ft. buries to a cablehead in, or even in advance of, the front line. Cable detachments were organized and held in readiness to extend the lines. Runners and despatch riders were organized in relay posts along the cable route. Wireless and power buzzer sets were also erected in convenient dugouts close to cablehead and the forward communication centres. By this concentration of means along one line, and by an all-round training which made the personnel to some extent interchangeable, economy of personnel, elasticity of procedure, and a minimum of casualties were ensured.

In the more extended offensives of 1917, this principle was carried still further and reinforced by instructions issued by G.H.

Q., which required the headquarters of formations to give the signal officers concerned early and detailed information as to projected operations, forbade movements of headquarters without good cause, and laid down other important points of principle.

The culmination of position warfare thus arrived in the spring of 1918 to find the signal service quite equal to the calls made upon it. At G.H.Q. and on the lines of communication were adequate office staffs and a sufficient number of permanent line and airline construction companies and sections. The bases, camps, depots, and stores concerned with the administration and supply of a great army were served by army telegraph and telephone routes. Maintenance parties at all offices dealt with ordinary day-to-day repairs; breakdown gangs at central positions were in readiness to cope with the catastrophic breaks due to bombing and long-range shelling. At G.H.Q. itself powerful wireless stations formed the initial link of a chain line which reached right forward to the front line; other stations were engaged in intercepting the German wireless; and a headquarters wireless staff coordinated the activities of the Intelligence stations scattered throughout the rear army zone. Here, also, was the nerve centre of the whole signal service in France - the directorate of signals - the staff which formulated the policy of the service, supervised its organization and working, and allocated the incoming reinforcements of men and material.

The basis of the signal system of the army was again a telegraph and telephone network which was built up on a " chessboard " or " grid " system, that is with front-to-rear routes and routes transverse to the front, spaced at regular intervals and with the main signal offices and test-points at the junction of the two. Until late in 1917 the approved theory was to make the line system approximate as nearly as possible to the perfect " grid " with as few and as heavy routes as possible. With the increase in the amount of longrange shelling and bombing which was a marked feature of early 1918, this principle required considerable modification. Two or three parallel routes usually took the place of the single heavy route of each corps or arm y area, and all routes were diverted to a much greater extent in order to avoid centres likely to be bombed or shelled.

The constitution and working of the army signal company perhaps more nearly reflected the conditions of position warfare than did that of any other. A telegraph construction company, a light railway signal company, and airline sections were the chief elements of the construction personnel, though there were also cable sections for connecting up isolated units at any time, and dealing with emergency connexions in battle. 'Here, also, were wireless light motor sections, mainly employed on supervisory duties, but like the G.H.Q.

t Strictly, this applies only to corps and army headquarters, though before the war ended, it was the unofficial practice in most divisions also.

wireless, available to take their place in the chain of intercommunication in the event of the failure of the lines. Most of the traffic was dealt with by wheatstone, duplex, and simplex telegraphy, and the magneto telephone, wireless telegraphy being 'chiefly utilized to assist and police the more forward stations. The chief signal officer of the army had also to coordinate the signal schemes of the formations in his army, and under his command were the area detachments whose permanent duty was the maintenance of the buried cable in the army area.

In the area of a corps - the forward position of which was liable to frequent shelling - the main routes were still permanent line and airline and the construction personnel consisted in the main of airline detachments. In addition, corps cable sections were available for emergency cable-la y ing, for loan to overworked divisions (a frequent case), for artillery signal. work, or for running spurs to isolated offices off the main airline routes. The personnel of the corps cable sections was also often employed to supervise labour parties in the construction of the buried cable system, though, as above mentioned, maintenance personnel was provided through the army area detachments. The corps wireless section, while principally concerned with store distribution and supervisory and police duties, was more intimately connected with the tactical employment of wireless than was that of the army. Particularly in battle periods, the corps-directing station was frequently obliged to step in and assist its less powerful subordinates to attract the attention of other stations or to rebuke stations using undue power or contravening priority regulations, besides policing procedure and listening for occasional windfalls from forward German stations.

Lastly, the chief signal officer of the corps had to supervise and control the signal communications of the heavy artillery. For this purpose a special section had been added to his company, but this was altogether inadequate and in practice the whole energy of one corps cable section was usually devoted to the construction and maintenance of artillery lines. These corps units were differentiated in principle from the area detachments by the fact that they possessed sufficient transport to enable them to move forward while continuing their work. In all adaptations of the signal units of formations below army the essential characteristic of mobility was respected. Those elements of the service which required to be specialized to areas were embodied almost entirely in the army company, others being organized so as to be able to move as integers.

This principle of mobility naturally applied with still more force to divisional signal companies. Even when position warfare seemed to be most definitely established the retention of its horse transport by the divisional company was insisted upon, in spite of the extra work entailed by the care of horses upon a personnel fully occupied with its technical work. This insistence had its reward in the long run, for mobility regained all its old importance on March 21 1918 and retained it to the end of the war.

The original divisional signal company in 1914 consisted of the following elements - three " brigade sections " (in principle serving the infantry brigades), each of a telephone detachment and a squad of signallers, a " headquarters section " consisting of a small office staff and a few signallers and despatch riders, and a " No. 1 section " of three cable detachments, each of which was capable of laying 10 m. of cable and carrying three offices. By the spring of 1918 the " headquarters section " had been enlarged in every branch, and " No. 1 section " had been increased to four detachments to cater for the field artillery headquarters; but the " brigade sections," though much overworked, had remained practically unchanged. To these three original elements, however, others had been added.

A small section, similar to a " brigade section," was serving with every field artillery brigade in the division. The reorganization of the machine-gun service in Feb. 1918 added another small section to serve the divisional machine-gun unit. The extension of wireless telegraphy to the division had involved the addition of sufficient personnel to man a " Wilson " and three " 50-watt " sets and a charging set for accumulators. In addition, men were attached from brigades to man six power buzzers and their corresponding receivers, and to eke out the still undermanned visual detachments.

Forward of battalion headquarters, the direct responsibility of the divisional personnel ceased and, in battalions and batteries, signal communications were built and maintained by regimental signallers. Occasions occurred when the requirements of these units could be accommodated on the central system, but these were exceptional. Usually their signallers were fully occupied with the lines and with visual communication between the front line and their headquarters. The means at their disposal were light cable lines and enamelled wire with D3 buzzer telephones; heliograph, lamp, fla g, 2 disc, or shutter; pigeon, messenger dog, message-carrying rocket and runner. In the case of power buzzer, pigeon, and messenger dog, communication was usually roundabout, via brigade, division and even corps headquarters; in the case of other appliances, direct touch from front line to company headquarters and from company to battalion headquarters was the rule.

The most interesting portion of the evolutionary history of signal communication in the war finishes with this period, and the story 2 The artillery still used both Morse and semaphore; infantry signallers at this stage of the war were trained in Morse only.

of the remaining months of mobile warfare is that of the reversion to simple skeleton systems, based on the principle of the central route studded at suitable intervals with forward communication centres. No further radical reorganization took effect, the principal change being the gradual switching over from spark to continuous wave wireless for command intercommunication purposes.

1 (3) Signals in Theatres of War other than France

2 (5) Means of Intercommunication

3 Wireless Telegraphy and Telephony

4 Visual Telegraphy

5 Message-carrying Agencies

6 Notification Signals

(3) Signals in Theatres of War other than France

While the greatest measure of evolution and adaptation naturally took place in the most important field and that nearest to the home sources of supply, almost every one of the outlying British theatres of war presented its special problems and emphasized the need of forethought and careful preparations, in respect of methods, personnel and stores alike, to suit local conditions, for instance in arranging for intimate cooperation with the intercommunication service of the navy in such operations as those of the Dardanelles, and the coastal operations of Sinai and Syria,' and in assigning an unusually large part to visual and wireless communications when a considerable water gap has to be spanned, as in the Dardanelles campaign. But perhaps the most significant lesson of experience in these campaigns was the greatly enhanced importance of wireless telegraphy relatively to other means of communication. Wireless plays a predominant part in such operations as those in E., W. and S.W. Africa, or those of the desert mounted corps in Palestine, which are conducted in vast, ill-developed theatres of war by comparatively small forces; for these frequently involve far-flung troop move ments in the offensive, and tactical isolation of detachments in the defensive.

The sets in use in the British Expeditionary Forces engaged in outlying theatres were the 3-K.W. lorry set; the 12-K.W. set mounted on a limbered wagon and drawn by teams of horses, bullocks, mules, or even men; and the Marconi pack set, a o

5-K.W. set either carried in a limbered wagon, on pack horses or mules, or by bearers. The latter proved particularly valuable for work with flying columns of swiftly moving troops. All three types of set were spark sets deriving their energy from internal-combustion engines. In the future, these will doubtless be replaced by the more efficient continuous wave system of wireless, but they played their part well in the 1914-8 campaigns over ranges respectively of 120moo, 80, and

30-50 miles. The extreme case of isolation in the defensive is of course that of a garrison under prolonged siege, and as an example both of the utility of wireless telegraphy in this case and of the actual working output of even a small set, the case of Kut may be quoted. The only means of signalling possessed by the defenders of Kut for some weeks was a small wireless set. By means of this, touch was kept with the relieving forces until the surrender, 6,313 messages consisting of 434,861 words in 144 days being the final record of the set.

One other lesson learnt in the outlying campaigns may be mentioned - the special necessity, in the theatres far from home supply services, for standardization of implements and stores. This had only been partially carried out when the war ended, but since then a considerable reduction has been effected in the number of types of instruments in use.

(4) Relation to other Arms. - A subject of considerable importance is the relation between signals and other arms. Before the World War, the signal service was regarded by the general staff as an executive servant and by other elements of the army its existence and potentialities were too often slighted or ignored altogether. As the war went on, the importance of rapid, trustworthy, and copious intercommunication was emphasized more and more. The effect of this, in the gradual change in the status of the formation signal officer from the executive to the staff officer, has already been emphasized as one of the main features of the evolution of the service during the war period. Similarly, the relation of " signals " to intelligence, artillery, and even to infantry, has undergone a distinct change.

The intelligence service of all armies owes no small measure of its present effectiveness to the means provided by signals for tapping sources of enemy information. The listening sets; the position-finding wireless set; the interception wireless set; the 1 It was doubtless owing largely to the experience of these campaigns that steps were taken towards the end of the war to harmonize the signal procedure of the navy, the army and the postoffice, that is, the form and manner of sending messages, the checks in accuracy, the ensuring of priority, and suchlike matters of technical detail that, in fact, are as important to efficiency as the design of instruments and the principles observed in their employment.

aeroplane wireless compass, are all efficient means of making out enemy plans and dispositions. So-called "wireless camouflage" 2 and the dissemination of false information by all means of signalling are well-recognized strategems.

The relation between artillery and the signal service is still more obvious. Efficient artillery fire was never more dependent on good observation than it was in the position-warfare battles of 1915-7, and observation is useless without intercommunication. As has been noted earlier in this article, artillery signal communication has become one of the definite functions of the signal service.

With the infantry, the signal service, through the regimental signal personnel which it supervises, has an equally close connexion, though the personal comradeship which is the basis of true liaison was made difficult, in the war, by the inevitable demands made on infantry labour for the burying of cables.

Signal personnel have frequently proved their ability to give a good account of themselves in infantry fighting, but it cannot be too strongly emphasized that the employment of signallers as infantrymen whether in the battalion, brigade, division, corps, or army, is a mistake except as a very last resource. The signaller is a valuable technical tradesman and he cannot be trained in a few days or even a few months. More casualties have probably been caused by lack of signallers, and therefore of the efficient signal communications essential to the guidance of the battle, than can ever have been saved by their employment in the fighting line.

No small amount of the attention of signal units, especially in position warfare, is now devoted to serving the needs of other technical branches of the army. Tank corps, royal air force, and survey battalions all made special demands upon the intercommunication service.

(5) Means of Intercommunication

Details of the means of intercommunication employed by the British army signal service will be found in the official Manual of the Corps of Signals, Parts I., III., IV., and V. Some of the details of more general interest are given in the following few paragraphs.

standard instruments in use are the telephone No. rIo (magneto ringing), the fullerphone (buzzer call) and the telephone D Mk. III. (buzzer call). (In addition, a lineman's telephone is provided for the use of the intercommunication maintenance personnel which has both magneto ring and buzzer call.) Of the telephones, no special description is needed, their only peculiar characteristic being a robustness of structure and parts calculated to stand the rough usage of army life.

The fullerphone is an instrument of peculiar interest. The chief cause of the leakage from telegraph and telephone circuits was the electrical stresses set up within the earth by the rapidly alternating current used. The fullerphone is a telegraph instrument, the essential point of which is the changing at the receivin end of a steady current into an intermittent current of audible frequency, while at the same time the current in the line remains steady. A typical fullerphone receiving circuit is shown in fig. 2. The interrupter (X) may be driven by any means, either electrical or mechanical. In army patterns it is driven electrically, being operated by means of a local cell.

If a steady E.M.F. is applied between line and earth and the circuit is closed at the interrupter, a steady current will pass through the choke coils (Ci, C2), contact 2 and receiver. If the circuit is broken at X the current cannot pass through the receiver but will flow into the condensers (Kr, K2, K3). When the circuit is again closed at X the condensers partially discharge through the receiver. When the interrupter is working we therefore get an intermittent current in the receiver which can be made audible by adjusting the interrupter to run at a suitable speed, while the line current alternatel y runs into the condensers or through the receivers and remains practically constant and continuous in the line. The dots and dashes sent by the single current Morse key at the end of the line z Manipulating the technicalities and the volume of traffic of one's own wireless so as to mislead the enemy's interception service.

Secondary C:.

Cz

FIG. 2.

are therefore reproduced in the receiver as short or long notes. Readable signals can be obtained with about half a microampere, a main battery of one dry cell being sufficient. The employment of such an extremely small continuous line current eliminates danger of overhearing, induction being reduced to a minimum.

In the rear areas, simplex, duplex, and wheatstone telegraphy are all used in the offices of the higher formations, which in the case of the armies may contain several hundred telegraph instruments and telephone subscribers. Magneto exchanges are the rule as far forward as brigade headquarters. At brigade headquarters buzzer exchanges are also installed and at battery and battalion headquarters buzzer exchanges are the rule. Circuits are of galvanized iron or copper wire beyond the limits of frequent shelling. Forward of this, main routes are of buried armoured cable (2-, 4-, or 7-pair brass-sheathed or iron-armoured usually) or light field cables which are standardized in several sizes in both single and twisted twin circuits. Enamelled wire, that is, wire roughly insulated by a coating of enamel, was used by forward troops during the war, but is now obsolescent.

Wireless Telegraphy and Telephony

In all formations down to infantry battalions continuous wave wireless is now practically the only means used. There are three standard sets. For use at, or in rear of, army headquarters, or for long distances in mobile campaigns, a set is provided with a maximum range of 400 miles. The set has two 70-foot masts and is fitted to be carried either in a box car or a limbered wagon. (This is the equivalent of the former " heavy motor set.") For distances up to 200 M. a smaller set is provided which has two 40-ft. masts and can be carried as above or on pack animals. For divisional work, the old " Wilson " and " British Field spark " sets have been replaced by a portable set with a range of 12 miles. This has two 15-ft. masts, is worked from accumulators or by a hand generator, and carried on pack animals or by bearers.

Finally, the loop sets already mentioned earlier are retained for work within the battalion and battery if required, though they are likely to be replaced soon by short range and short wave C.W. sets of much greater efficiency. The power buzzer and 3-valve amplifier sets are also available for issue in case of position warfare.

Small portable wireless telephone sets for forward work have been devised, and similar sets were indeed used in the Air Force during the last months of the war. The sets are not yet standardized, but those in use have a range of some 2,000 to 3,000 yards.

Visual Telegraphy

The visual instruments include the heliograph as used in pre-war days (see 13.223); the Lucas lamp; the shutter, and the flag. Of these, the heliograph has a range up to Ioo m. or more, but is only of really extended use in a country with a large proportion of sunlight.

The very efficient and portable Lucas lamp is a powerful electric lamp with an 8-candle-power bulb set in the back of a cylindrical lampholder with a powerful reflector at its back. An 8-cell battery of ever-ready cells provides a current at an E.M.F. of 12 volts. The lamp has a range in daylight of 2 m. with the naked eye and 3 to 4 m. with the telescope, and at night of 6 m. with the naked eye and twice that distance with the telescope.

The signalling shutter is also a development of the position-warfare phase of the war. It consists of three flaps of American cloth which are black on one side and white on the other. At the back of the shutter are metal clips by which the device can be attached to an ordinary bayonet. The flaps are normally closed with the black side outermost, but by pulling on the operating cord they are pulled down and the white exposed. On releasing the cord the flaps spring back to their original position. When not in use the instrument can be rolled up and stowed in a canvas case.

Message-carrying Agencies

Of these the most important are (a) despatch riders, mounted orderlies, or runners; (b ) carrier pigeons; (c ) message-carrying rockets; (d ) dogs; (e ) air craft.

(a) For use in rear of brigade headquarters the motor cyclist despatch rider is invaluable. A feature of the modern signal service is the organized D.R.L.S. which deals with all official correspondence too urgent for post and not sufficiently urgent for the telegraph. Within brigades, divisions, and in cavalry units and formations, mounted orderlies are often used for conveying messages and this is true of all formations in country impassable to motor cyclists. In the forward battle zone the runner is the last resource of the forward commander. His use should, however, be restricted to occasions when all other means of signalling have failed or are unreliable, for casualties amongst runners are many and men suitable for this duty are not too common.

(b) The pigeon has proved its value for position-warfare conditions during the war. The pigeon service is controlled from corps headquarters and messages from the trenches will usually reach the battalion via brigade or divisional headquarters. The employment of pigeons with tanks and artillery is an important branch of the pigeon service. New developments are their delivery to isolated or front-line posts by aeroplane and parachute, and the teaching of pigeons to fly by night. In the latter case the birds are kept in red light and are flown to a loft where the trap is illuminated by a powerful arc or acetylene light.

(c) Message-carrying rockets with a range of 2,300 yd. have been adopted as a standard means of signalling. Their course through the air is outlined by a trail of smoke and their position at the end of their flight by a coloured flare automatically lighted at the moment of impact with the ground.

(d) The use of the messenger dog is likely to be confined to position warfare. These dogs have done good service on occasion, but are likely to find their vocation only in stationary warfare or during a very methodical deployment for battle.

(e) In certain phases of a battle the aeroplane is the only trustworthy or even possible intermediary between troops and command. Apart from wireless telegraphy, messages can be communicated to the aeroplane by visual signalling, or if of a simple conventional character, by means of the ground panels used for the notification of positions, while, from the aeroplane to the ground, the most secure method yet discovered is to drop a written message, provided with long streamers, on to selected " dropping grounds " contiguous to the headquarters concerned.

Notification Signals

Light and smoke signals are made use of as occasion directs and a plentiful supply will be held in store. These are used, under prearranged schemes, for such purposes as calling for barrage or protective fire; notifying positions of forward troops; answering one-way messages, etc. The manufacture of distinctive flares, and light signals generally, has been carried to a very high degree of perfection.

Acoustic signals have not been generally successful with the exception of the Klaxon horn in aircraft. Special sirens and horns for calling attention to gas attacks and other general alarms have been much used, but an attempt made by the French to signal by means of tuned acoustic horns was not very successful. The noises of a modern battle are such as to handicap this method of conveying information very greatly.

(6) The French Signal Service. - The French intercommunication service at the outbreak of war differed from the British in being in two separate compartments - a telephone system controlled by the engineers, and a runner and despatch rider service under entirely separate direction. In addition there existed a motor service with the maintenance of liaison between units as its chief duty. The absence of the telegraph in forward formations threw much extra work on the remaining personnel, and caused a consequent increase in the proportion of despatch riders, runners, and orderlies. Construction personnel was in the main kept in the rear and sent forward only when actually required, according to exigencies.

The greatest reliance was placed upon the ringing telephone even in the forward area, and this statement is true even for 1918, although time and again the forward telephone system had been swept away in hopeless ruin by the bombardments which preceded the great position battles. In the rear, the very complete telephone network with an excellent system of locality exchanges served all purposes very well, whether in the normal stationary warfare, in the pressure of traffic before or during an attack from a trench system, or in the hurry of an advance or retreat on a considerable scale. In the last-named case as the attacking armies very soon outran the major portion of their heavy artillery, these well-built lines stood well, and the French system of locality exchanges served the retreating divisions as well as it had served the corps and armies for which it had been originally built.

In the forward area the French signal service was faced with a somewhat different problem from that which confronted the British. Serving a professional staff and a conscript army, far more accustomed to mass manoeuvres than the British armies, a relatively far greater proportion of attention could be paid to getting back information from the front than orders forward to the front. The absence of the telegraph had also taught the forward staffs to rely more upon the spoken word and to dispense to a great extent with those written explanations and confirmations of orders which were considered essential to the British staff procedure.

The British subordinate commander was often able to act upon his own initiative; his French equivalent was not only able but expected to do so to a much greater degree. The result was a far greater use of one-way working, and to this was perhaps due the fact that the power buzzer-essentially a one-way instrument - was first developed in the French army.

A further fea


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Bibliography Information
Chisholm, Hugh, General Editor. Entry for 'Army Signal Service'. 1911 Encyclopedia Britanica. https://www.studylight.org/encyclopedias/bri/a/army-signal-service.html. 1910.

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Monday, November 18th, 2019
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