The Signal Service in the European War of 1914 to 1918 – Chapter 8

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«-- The Signal Service in the European War of 1914 to 1918
Chapter XIII
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Chapter VIII


The Somme Offensive. — Three Types of Signal Problems Involved. — Organization of Signal Communication Schemes. — Signals in the Limited Offensive: Forward Cables, Runners, Pigeons, Visual. — Signals in the General Offensive: Forward Cables, Pigeons, Visual. — The Lucas Lamp. — Aeroplane Signalling. — Battalion Signallers. — The Brigade Pool. — The Re-appointment of the Battalion Signal Officer. — Divisional Signal Schools. — Runners and Relay Posts. — Signals in Slowly-moving Position Warfare. — Wireless. — Wireless through German Eyes. — New Methods of Forward Signalling: Power Buzzers, Message-carrying Rockets and Bombs. — Acoustic Horns.

In the general discussion on the evolution of the 6 ft. buried system in the previous chapter, reference has been made to the important part played by this system in the battle of the Somme. Where the 6 ft. bury had been completed to battalion headquarters before an attack, or better still, to the front line or well out into "No Man's Land," anxiety was relieved as regards intercommunication in rear of cable-head. Where this did not prove feasible, on the other hand, the shallow buries or trench cables were a source of constant anxiety and loss. Telegraph and telephone communication was at best intermittent, and often non-existent.

The lessons of the battles of the Somme, and the modifications in signal practice and organization which were brought about as the result of this first great offensive carried out by the British Army, are best considered in two main sub-divisions. These are, respectively, the alteration in methods of forward signalling, and the general modifications of signal organization and policy considered in their broader aspects. It is the former that it is proposed to consider somewhat in detail in the present chapter.

Never before had the Expeditionary Force been engaged in warfare approaching in intensity that of the Somme battles. The enemy was well-hidden and well-protected in a system of trenches and redoubts on which he had spent eighteen months of painstaking and intelligently directed effort. Across the face of France stretched at least four series of completed lines, immensely strong, with all salients converted into self-contained forts, and with the fullest possible use made of the opportunities for enfilade fire. In front of the lines of defence were belts of barbed wire, 40 yards or more in breadth, and of great strength and intricate entanglement. True, it was the task of the artillery to demolish, and of the infantry to assault and over-run these defences, yet the Signal Service was equally concerned, for it was the thorougliness of our own bombardment — necessary for the obliteration of wire, trenches and strong-points — which formed one of the great obstacles in the way of following up the advancing troops with a line system capable of serving their needs.

The features of the Somme battles were undoubtedly the length and power of the preparatory bombardments which preceded each attack, and the weight of the enemy's retaliatory barrage which fell upon our front line and the country immediately in rear of it immediately an attack was launched or even suspected. The growling thunder of the guns which was part of the normal routine of trench warfare, rose on occasion to an inferno of shrieking shells and crashing explosions as the barrage or area bombardment blasted out of its path every living thing that could not seek instant shelter in bombproof dug-outs or deep communication trenches. The very villages and towns which stood across the path of our advancing troops and which had been converted by the enemy into miniature fortresses, were obliterated and shot away. In many cases, not even a pile of bricks marked the places where once tranquil village life flowed on as if war were not and could never be. For the first time, the Germans themselves experienced what the fury of modern weapons really could achieve. When the battle commenced, the main weight of the enemy's own artillery was concentrated further to the south, supporting and enforcing his assault upon the Verdun fortresses and defences. As the attack was pressed home, however, and he realized that his boasted defences were not impregnable, he concentrated more and more guns opposite to the menaced portion of his front. What with the battered and sodden nature of the country over which the long drawn-out conflict took place, and the weight of metal brought to bear on the contested area by the enemy artillery, the problem of forward signals was well-nigh insoluble.

The battle of the Somme in 1916 may be divided from the point of view of the British Army into three main phases. The initial attack of July 1st with its comparative success on the southern portion of the front, was followed by some months of a moving siege warfare. In the second phase, attack after attack was carried out, now on a Brigade front, now on the front of a Division, now on that of a Corps. Each attack had a definite objective of limited extent; each was carefully prepared; each was followed by a period of comparative quiescence or by enemy counter-attacks by which he endeavoured — usually without success — to oust our men from the ground they had gained. The third and last phase of the battle was concerned with the pushing of the enemy down the forward slopes of the plateau. A conspicuously successful general attack was accompanied by a series of voluntary withdrawals by the enemy and was succeeded by a few smaller actions which left the British line in favourable position for the coming winter.

The intercommunication problems of the campaign are also best considered under three headings. Three distinct problems were presented for solution by: — (1) the individual carefully-prepared attack with a limited objective; (2) the successful surprise attack which involved an advance sufficiently widespread to cause movements of headquarters, and (3) the slow-moving siege warfare which took the fighting formations off the deep-buried system and made necessary temporary reliance on a far less secure line system. It is proposed to deal with these three phases separately in the order in which they are given above. In the first two cases the problem was that of crossing "No Man's Land" and following up the advancing troops with the best measure of signal communication possible. The main requirements of troops in an attack were three in number. The supply of reinforcements and ammunition must be maintained. Sufficient direction must be given to the batteries to enable them to lengthen their range, and concentrate their fire on more distant objectives, while the infantry carried by assault the defences already pulverized. Information of approaching counter-attacks gained from other sources than direct infantry observation must be conveyed to the first line troops and artillery in good time to enable them to crush the attacks. In addition, for the benefit of the higher command, information must be brought back by some means to keep the Brigade and Divisional Commanders in touch with the situation and able to ask for help from higher formations and to utilize their own general reserves to the best advantage.

These requirements appear simple as stated in broad outline, but for the efficient conveyance of orders and information some measure of signal communication was essential. Telephone communication if possible; if not, any supplementary means which best suited the situation. During the battles of the Somme, forward signal units had at their disposal visual, including communication to aeroplanes and kite balloons, contact patrol aeroplanes, pigeons, mounted and motor cyclist orderlies, runners, wireless and the new untried earth induction sets. The main feature of the story of forward signals during the offensive consists in the combination of all or some of these means into schemes, and their organization individually to form a chain of intercommunication between the most advanced troops and Brigade and battalion headquarters or cable-head.

One thing that early stood out among the lessons of the battles was the fact that different means must be used to suit different sets of circumstances. At one time visual would prove successful; at another pigeons and runners would save the situation. On occasion, wireless or the new power buzzers and amplifiers would prove the salvation of some isolated body of men hard beset in a captured stronghold. Again, favourable circumstances and a careful study of the enemy barrage would permit of the running of lines by a route safe enough to enable them to be maintained without undue sacrifice of life. Almost always, by one means or another, signal touch would be kept. Runners, for instance, could always be found who would make the effort to cross the shell-swept, corpse-strewn barrage zone. The lives of these men were precious, however. They must not be lightly thrown away. Casualties amongst battalion signallers and runners were normally heavy and at times 50 per cent. and over fell in a single battle. The advantage of visual, wireless, pigeons, and earth induction sets was that each — under suitable conditions — would successfully bridge the dreaded barrage zone. By their means news could be flashed or otherwise despatched through the ether or air from protected emplacements to stations situated at a safe distance beyond the zone of heaviest shelling. Air-signalling vied with ground-signalling, now one, now the other triumphing as the situation changed. The problem before the forward signal officer resolved itself into one of organization more than anything else.

Means of signalling were ready to his hand. It was his task to organize his personnel in such a manner that the greatest use was made of the most suitable means of communication with the least number of casualties. The measure of the success achieved may be judged from the official tribute to the Signal Service in the dispatches which describe the battles of the Somme.

"The Signal Service, created a short time before the war began on a very small scale, has expanded in proportion with the rest of the Army, and is now a very large organization.
"It provides the means of intercommunication between all the armies and all parts of them, and in modern war requirements in this respect are on an immense and elaborate scale.
"The calls on this service have been very heavy, entailing a most severe strain, often under most trying and dangerous conditions. Those calls have invariably been met with conspicuous success, and no service has shown a more wholehearted and untiring energy in the fulfilment of its duty."

To consider the different situations a little more in detail, the simplest case worthy of particular attention is that of the attack on a Brigade or Divisional front with a limited objective. A certain section of the enemy's defences was subjected to a fierce whirlwind bombardment of a few hours, or at most one or two days, and was then assaulted by the infantry. The advance was usually to be a few hundred yards only in depth: it seldom would exceed a mile. The outstanding feature of this type of attack was the absence of movement of any of the major headquarters. Battalion headquarters, possibly even Brigade headquarters, might move forward after the consolidation of the captured position. Such a move, however, was carried out at leisure and could be catered for by the forward extension of the deep buried cable on an ordered plan and by means of organized working parties. During the attack itself, and during the period when the enemy counter-attacks might be expected to materialize, no such forward move would be likely to take place.

The essential preliminary for such an attack was to have the cable-head of the deep buried system as near as possible to the front line. If two or three days' notice had been given, this would be carried out; if not, the proportion of the line communications which must be considered unsafe included all lines in advance of cable-head, and additional supplementary communication must be provided accordingly.

In either case, the position of cable-head would be published in operation orders. One of the main lessons of the Somme battles, and of other offensives also, was that the position of signal offices, cable-heads, test stations with spurs to which units could connect, central visual stations, pigeon posts, wireless stations, and all other means of despatching messages could not be too widely circulated.[1] It was of no use establishing stations unless their position was known to all the officers, and as many as possible of the rank and file, of the troops whose needs they were intended to serve. Cases occurred on the Somme when, for longer or shorter periods of time, the situation was obscure and the Staff had to rely partially or wholly on news collected by Signal Service officers and N.C.O.'s. Indeed, this difficulty of obtaining information was so real and so pronounced that it was legislated for in the Manual on "Intercommunication in Battle," issued by the General Staff in 1917.

Forward of cable-head, lines up to the front trenches were made as safe as possible, but it was recognized that all or some were certain to be cut during the attack. Various methods of making the trench line system safe were tried. Laddered lines were still in favour, but were used more in the general attacks to be referred to later. Rabbit netting was also still used on occasion. Narrow, open cable trenches were frequently dug. Armoured cable buried beneath the sole of the trench was much used at first, but was not very satisfactory.

Generally, the only marked development of trench cable for attack in 1916, was in the direction of a greater orderliness of system and more attempt at protection. In one case "D2" cable was buried in a communication trench, by undercutting the side nearest the enemy to a depth of one foot, and filling earth in on the cable. Eight days' heavy bombardment completely destroyed the trench, filling it in and obliterating it in many places, yet this cable was never damaged.

The employment of cable with the assaulting troops differed with the ideas of signal company commanders and brigade section officers, with the requirements of the situation, and with the terrain over which the attack was to take place. In an attack with a limited objective it was usually possible to take light cable over with the the first assaulting troops. Provided several cables were taken by alternative routes, and were laid with due regard to the avoidance of places likely to be shelled, one cable at least might remain unbroken sufficiently long to be of vital use. Indeed, several cases were recorded in which such frail threads remained through until diminution of the enemy's fire enabled the bury to be dug forward towards the new front line. One scheme given as an example of a successful attempt to carry forward line communication is as follows:

"Each company should detail three or more signallers, each with a telephone and a reel of "D1" cable. The latter should be fixed to an instrument in the front trench and securely tied back to prevent any strain from coming on the instrument during the process of laying. A definite point in the enemy's line, to which these men are to make their way, should be decided on previously. This point should be published in orders and should be explained to all ranks as being the Report Centre to which all messages should be taken.
The signallers should advance with or immediately behind the advancing troops, as it has been proved by experience that, provided the wire entanglement has been properly cut, the first line generally reaches the trench without much difficulty. They should advance, one behind either flank of their company, and the third about the centre, keeping well apart and converging on the point previously settled upon as the Report Centre. With any good fortune, one at least should get through with his line in safety"

The above system was tried in practice, and, on one occasion, communication was kept with the third line of German trenches for six hours and, on another, with the first German line throughout the day. It is typical of the kind of scheme tried with varying success in many attacks by Divisions, Brigades, or battalions, and served as well as any other modification of forward signal practice.

In the great majority of attacks with a limited objective, however, the enemy artillery retaliation was so heavy that lines could not be relied upon to remain through. Once the enemy barrage had come down on the old front line, and his bombardment of the captured trenches had commenced, the attempt to maintain or lay new lines might usually be discontinued as causing useless waste of life. On rare occasions, when direct observation was impossible and the initial calculations of the enemy artillery were at fault, a "patchy" barrage might open up possibilities in this respect. Even if this were so, however, all descriptions of traffic at once converged upon the safe route.

Ground lines, even if they escaped the enemy's shells, could not be expected to survive the constant stream of walking wounded, reinforcements, orderlies, limbered wagons, stretcher bearers and other miscellaneous traffic. A well-worn track appeared at once and momentarily expanded in width. Along this, feet and wheels would rapidly trample and churn out of existence the strongest cable. The signal officer must make the most of the route by organizing thereon a runner service, or possibly, if distances were sufficient to warrant their employment, or the road dry enough to permit of the use of motor cycles, a service of mounted orderlies or motor cyclist despatch riders. By one or all of these means, communication could be kept up between the report centres and the cable-heads in rear of our original front line.

Even where, as more often was the case, no well-defined shell-free path could be picked out, runners were still of necessity used in spite of heavy casualties. Cases often occurred where messages, although sent in duplicate by successive runners, failed to reach their destination. Visual and pigeons were used to supplement the runner service, but each means had its limitations. Pigeons could not be used at night[2] or in heavy mist; visual was impossible either in mist or through the smoke and dust of a heavy bombardment. Another factor which acted against the use of pigeons was a shortage of birds which kept down the allotment per company for specific actions to two birds. In such cases, one of two things was quite likely to happen, according to the temperament of the company commander. Either he might be anxious to establish communication immediately and liberate both birds with comparatively unimportant messages, or he might, on the other hand, consider his pigeons as his last resource and hesitate to part with them at all. In the latter case, he would as often as not retain the birds while opportunity after opportunity for their use passed, until, finally, they were released with a quite formal message at the close of the 48 hours which was by rule the limit of their stay at any one time in the forward trenches. Some nicety of judgment was required in the use of the birds, but they were often of the utmost value at crises when all other means of communication had failed and the bombardment was of such intensity that to despatch a runner would have been to send him to certain death.

The short distances involved in the type of attack at present under consideration, were within the range of all visual appliances. When conditions were favourable, that is, in lulls of the barrage in clear weather, or even when wet weather prevented a great accumulation of dust in the atmosphere in spite of the constant explosion of shells, this means of signalling proved of the greatest use. Flags, discs, and shutters were used over short distances; lamps of several types gave good results both by night and by day. The detailed consideration of the long-range visual apparatus is better considered in connection with the second and more general type of attack where greater distances were involved. The Dietz and "ping-pong" discs have already been mentioned, for they rose to favour in the 1915 battles. The Louvre[3] shutter was, however, new. One little device connected with the latter is perhaps interesting as being the direct outcome of the experience of the Somme battles. As in the case of the Begbie lamp, one great drawback of the earlier type of shutter was the noise made when the springs were drawn out to their full extent and released. This was overcome by the employment of a "stop" which prevented the movable leaves of the shutter from completely opening and closing. A further improvement in order to increase portability and decrease the conspicuous character of the first rigid shutters was the invention of a fold-up pattern which could be unrolled for use and fixed to the end of the signaller's rifle, to a fixed bayonet, or to any convenient pole.

An even less conspicuous type of visual apparatus of the same order was the "Watson" signalling fan, which was designed for signalling over short distances. When closed up, this instrument was very inconspicuous. It had also the additional advantage of being suitable for use, if spread out on the ground with the light face uppermost, for pointing out the presence of the troops to the contact aeroplanes which played a prominent part for the first time in these battles.


The second case to be considered is that of intercommunication during a general attack carried out with the avowed intention of breaking the enemy's line. Here the same main features repeated themselves, but in addition the problem was complicated by the entrance of two further important factors: — advance to a considerable distance, and the movement of formation and unit headquarters which this involved.

Once more, the system of forward signals was based upon a good deep buried system carried forward to cable-heads as near as possible to the front line. In the case of the first great attack on July 1st, the situation was complicated by the fact that the decision to bury cable had not been taken early enough. Where shallow buries were still in existence they were invariably broken in many places on the first day and were a continual menace to the efficiency of the Divisional intercommunication systems. They were often reinforced by alternative routes and by omnibus lines of poled cable run through all Brigade headquarters, but even so, line communication could not be considered certain. More reliance had, therefore, to be placed on the alternative visual system or on the trench wireless sets installed at Division and Brigade headquarters.

Forward of the buried system, line communication in the first stages of the battle was usually impossible. In many cases, Brigade section officers organized "forward parties" to carry forward wires with one or other of the assaulting waves. Usually, however, such parties were swept out of existence — as parties — during the first few minutes of the advance. Casualties were high and the loss of one or two links in each chain was fatal to the attempt to link up the points in the enemy system which had been selected as Report centres.

Everything possible and reasonable to expect was attempted. A careful study of plans of the enemy defences, and of the aeroplane photographs from which these plans had been prepared, enabled a definite programme to be mapped out beforehand. Signal instructions were issued as part of the General Staff Operation Orders for each attack. All ranks were informed where they might expect the new Report centres to be in existence. Staffs agreed to accept these spots as the sites of their new headquarters.

The problem was not, however, so simple as it seemed. The devastating character of the preliminary bombardment altered the appearance of wide stretches of country. The strong points were, to all outward seeming, obliterated from the face of Nature. Without surveying instruments it was often impossible for the parties to locate them at all. Men wandered about the country for hours before they finally set up their office in a convenient crater or partly-destroyed redoubt or trench, and advertised their presence as best they could with flag or other marker. It was impossible to work to a time-table or conform to anything beyond the broad principles of the original scheme. Constant experiences of this nature convinced the signal officers concerned that it was better to wait until the situation had settled down before attempting anything in the way of a line system. When the enemy barrage was discontinuous, advantage was taken of the fact to run lines through the gaps and thus to lay out a system of laddered cable, wire netting, or even of simple ground or poled cable. Laddered cable in particular was often used with success, communication being carried on in dry weather in spite of over 50 breaks in the ladder.

In a successful attack which involved a considerable advance, battalion headquarters usually moved forward within a few hours. By careful selection of a route it was then often possible to connect up to the old cable-head with "D1" lines, which were later substituted by "D5" cable. These forward lines were poled as soon as possible and were then maintained by means of a suitable system of lineman's posts which were sited in captured German machine gun emplacements or dug-outs.

Quite apart from the shelling, the establishment of this forward line system was by no means easy. The bombardment had converted the country into an indescribable chaos of overlapping shell holes and craters of various sizes. Any man-made obstacles, it is true, had been shot out of the way of the cable detachments, but the hindrances put in their way were incomparably greater than those removed. Distances of the order of two or three miles had to be traversed over ground which even in dry weather was like the troughs and ridges of a sea lashed into fury by a myriad gusts of wind. When the wet weather which signalized the later months of the offensive set in, the ground became almost impassable. Indeed, the advance of the infantry was ofttimes limited by their physical endurance. When the ground was dry, men could make fair progress with reels on which were wound quarter mile lengths of "D1" cable, and in this way the initial light line was usually laid. The "D5" cable which was run out as soon as possible to replace these "D1" lines was, however, a different matter. The provision of a single-horsed vehicle which would accommodate two or more "drums, cart, cable," was advocated by some signal officers. Proposal was even made that a, petrol-driven plough might be used with advantage to lay traffic-proof lines across this much-trampled zone, but the circumstances under which the machines would have been of use were so seldom realized that this was never attempted in practice.

The pack cable horses of the Infantry Brigade had been abolished in the previous year as being unsuited for stationary warfare. Had these been available they might have been of use under certain sets of circumstances, but these occurred so seldom that the pack horses and equipment were never really missed.[4] In many cases a pair of shafts were fitted to the normally man-drawn barrow which was part of the equipment of all forward signal units. These improvized cable carts were often of the greatest use and were employed largely both in the battles of the Somme and in the position battles of the next year. On one or two occasions in October, when the enemy made slight voluntary withdrawals to more suitable positions than those to which he had been forced back, cable wagons were used in the forward areas. Their use was, however, so exceptional as scarcely to merit mention. Finally, on the extensive mudfields which supervened all over the churned-up battlefields after the autumn rains, yet another type of transport appeared. The laying of many lines was only made possible by the use of the flat-bottomed sleighs which were specially built to meet a situation which bade fair to bring operations to a standstill.

Thus, by one means or another, it sometimes proved practicable to establish a measure of line communication within a few hours of the advance. Some means had to be devised, however, to keep touch during those first few hours and also to bridge the gap that here, as in the attack with limited objectives, always existed forward of battalion headquarters. These supplementary means must also be carried back to cable-head, wherever that might be, for Line communication forward of cable-head was never anything but intermittent. Various means by which this was achieved have already been indicated in studying the attack with limited objectives.

The problems due to the greater distances covered and the movement of headquarters involved in the more extended attacks were solved by more careful organization. A general line of advance was decided on beforehand and the signal communication was mapped out along this line, the only variations permitted being strictly local ones due to the unexpected situations which must always arise even, in the best-planned attack.[5]

Once the lines had been carried forward, there was a tendency for other means of signalling to "bunch" on to the same route. This was only to be expected since the lines went by the safest way, and this concentration much simplified the problem of organization of the despatch rider and runner service, which was still one of the mainstays of the Division and Brigade intercommunication system.

The chief supplementary means of signalling, placed in order of frequency of use in 1916, were runner, visual, pigeon. Nothing much remains to be said about either.

Pigeons were reliable, but few in number. Those which were available were found to be of more use if concentrated at battalion headquarters than if scattered amongst companies. In the latter case, the casualties increased out of all proportion to the number of useful flights made by the birds. At battalion headquarters, on the other hand, it was found that the birds were comparatively safe except when actually in flight. One small fact brought to notice by the experience of the Somme battles was the comparative immunity of pigeons to "tear" gas. One slight innovation which is of interest was the use by the dismounted cavalry Division in January 1916, of a wireless station to connect its loft at H.Q. at Sailly-la-Bourse with a receiving set in the front trench system. By this means, two-way working was established in a novel fashion. The experiment was, however, an isolated one, and, though successful, was rendered redundant by the fact that on the particular front where it was tried the situation was stable and the cables held.

The main lessons learnt by the organisers of the pigeon service during the Somme offensive was the necessity for an increase in the number of birds available for active operations. In the absence of an unlimited supply of birds, this need could only be met by an increased mobility of the service as it then existed. The result was the introduction of the "mobile" loft by means of which birds could be trained to a new front in a few weeks. As the number of mobile lofts increased, concentration on active fronts became a more practical possibility, and much more could be done with a given number of birds than under the old system of "fixed" lofts. The reconstruction of the pigeon service at the conclusion of a prolonged advance would also be much facilitated by this reform. A mobile pigeon service would have many advantages and at the end of 1916 the proposals for the formation of such a service were definitely put forward, the original figures being six motor and 60 horse-drawn lofts. Each motor loft contained 50 and each horse-drawn loft 75 birds, thus giving an addition of 4,800 pigeons to the service as formerly constituted.

The main lessons in visual signalling have already been summarized. The principle adopted was the establishment of as many protected receiving stations, both on the ground behind our old front line and on captured territory, as could be manned by the available personnel, or as topographical conditions would permit. A large proportion of the signallers accompanying the advancing troops were equipped with flags, discs or shutters, or with lamps. On captured ground, German machine gun emplacements were naturally ideal sites for forward visual stations.

First line troops also set up visual stations in convenient shell-holes or half-obliterated trenches, and flags were used from behind the remains of enemy works, though this latter method was the least popular of all. The feature of the procedure used was D.D.D.D. working, i.e., messages were sent from front to rear without an answer. They were repeated two or three times according to the individual faith of the signal officer concerned. Experience showed that triple repetition was advisable and this procedure was subsequently standardized in an order issued by the Signal Directorate.

Opinions differed very much as to the advisability of an acknowledgment to important messages. Certainly, the enemy were far too busy and disorganized in the opening stages of an offensive to permit of particular attention being paid to individual stations either with a view to reading the signals sent or of directing artillery fire against them. Equally certainly, visual signalling was not used as much as it might have been, because battalion signallers were doubtful if their messages were being received. Nothing seems more futile than signalling into space without any sign of the vigilance of a receiving station. On the other hand, the number of stations receiving was so great and they were usually so well-disposed, that almost all messages sent under conditions when visual was possible were received, often by several stations, certainly by one or two. The case might perhaps have been met by a single acknowledgment of the whole message, which would have been unlikely to provoke retaliation and certainly would have given away no information of value.

While signalling by day and over short distances was successfully carried out with discs, shutters and fans; long distances both by day and by night were frequently bridged by means of lamps. Of these, there were several types now available, amongst them being the French projector lamp No. 24, which gave good signals by day up to distances of 2,000 yards with the naked eye and 3,000 yards when a telescope was employed. The second type of lamp used, the service electric signalling lamp, was very much less powerful. It gave fair results by night, but was of little use by day. Two new types which were introduced for signalling to and from aeroplanes were the "Aldis" and "Hucks" lamps. These threw a powerful beam, but were worked by accumulators and were therefore not very portable. They also had too great a dispersion of the beam to be satisfactory for horizontal use between stations working within the possible field of view of a vigilant enemy.

These lamps, however, provided the main idea on which the future signalling lamps were based. Once again a decisive step forward in Army signalling was achieved as the result of individual enterprise when the "Lucas" lamp was designed by a gunner subaltern. Two types of the new lamp were produced — one, worked by accumulators and very powerful, for use with central visual stations, the other a smaller variety with a battery of eight dry cells as the source of power for forward stations.

Both lamps were distinguished by the strength and general efficiency of their component parts and by a most marked reduction in the dispersion of the beam. They were thoroughly tested on the Somme, enthusiastically reported upon by the Corps which had introduced them, and were later adopted with but slight alterations as the new standard signalling lamp. With their adoption visual signalling was once more given fresh impetus and gained markedly in efficiency. Daylight signalling by means of the Lucas lamp became the most popular and easily the most effective of all means of visual signalling in all climates which included a considerable proportion of over-cast weather, while the range of dispersion of the lamp made two-way signalling without enemy "overseeing" more practicable

Before leaving the subject of visual signalling in the Somme battles, mention must be made of a specialized form of signalling which first succeeded on a large scale in this offensive. The Somme battles were marked by the general employment of aeroplanes as a means of keeping touch between the forward infantry and the higher command. Certain aeroplanes were definitely detailed to serve specified formations and keep their headquarters informed of the progress of events. This could be done in two ways, both of which involved the use of some means of identification of the forward infantry.

For the latter purpose various means were employed, all of them at present in the experimental stage, and many of them giving indifferent results. Perhaps the most successful were those which depended upon direct observation from the aeroplanes. The observer would call by means of his Klaxon Horn for forward troops to identify their position.[6] One long blast, meaning "Where are you?" would be replied to by the burning of flares or the display of discs, fans or shutters on the ground.

At battalion or Brigade headquarters, large numerals or letters of white cloth on a black background were displayed to identify the headquarters; and for the first time the ground panel was used to send messages in a clumsy code. It was not, however, successful. The aeroplane observers were too slow at reading; the signaller on the ground was too impatient to be read. Messages sent by lamp were also seldom received, and, even if acknowledged, more seldom delivered at their destination. The new experiments in visual signalling were only of use as indicating the lines along which future progress might take place. By far the best reports from the aeroplane observers were those which were based upon their own observation, assisted by the use of flares or the display of other prearranged signals by the front line troops.

Once the observation was made, it might be conveyed to the Staff by two methods: by personal visit, or by dropping a message. The first method was more satisfactory if anything of paramount importance was to be delivered, but it involved a certain amount of delay and some risk, for good landing grounds were not common round about Divisional headquarters. As a rule it was far better for the aeroplane to drop its message on a selected spot where watchers were permanently stationed as long as daylight lasted. This means was more generally adopted and led to the establishment of definite headquarters "dropping grounds," the establishment of which became at a later date one of the responsibilities of the signal company of the formation.

Before the subject of visual signalling can be considered as adequately dealt with, something should be said of the battalion signaller. On these men the brunt of forward signalling fell. Among them occurred the greater proportion of the signal casualties. All forward signalling under battle conditions, whether it was the maintaining of the lines, the conveyance of messages by hand, or the watching for visual signals, involved a considerable measure of risk. From front to rear of the forward signal system casualties were common. Among the battalion signallers, however, battalions often reported the occurrence of 40 or 50 per cent. of casualties in a single action. This could not be permitted to continue. In the early days of the battle, many signallers fell in the ranks of the attacking infantry or on special duties which had nothing to do with signalling at all. The dangers of the situation were early realized, and pressure was brought to bear to enforce the policy of holding at least one-third of all the signallers of each battalion in Brigade reserve. These men were withdrawn from the battalion before it went into action and were used to replace casualties or to improve the forward signal system as occasion arose.

A further extension of this policy was later achieved by the formation of the "Brigade Pool." This consisted of eight signallers from each battalion in the Brigade who were permanently retained at Brigade headquarters under the orders of the Brigade Signal Officer. They were trained specially in visual appliances and with the power buzzer and amplifier. In action, they were utilized on any forward portion of the Brigade system of communications and in particular to keep communication between Brigade and Battalion headquarters by either of the above means, or to help man the Divisional visual system.

The whole question of the "signals" of a battalion was shown by the Somme battles to be on a somewhat unsatisfactory footing. The abolition of the Battalion Signalling Officer had been followed by a gradual deterioration in the qualifications of the battalion signaller and the organization of intercommunication within the battalion. As time went on, this was remedied to a certain extent by force of circumstances. In many battalions the Adjutant gave more time than he could well spare to the supervision of the signalling system. In others, the Assistant Adjutant was expected to devote a considerable proportion of his attention to the same work. In yet other battalions an unofficial signalling officer was appointed and gave his whole time to this very important duty. Success was achieved in proportion as the problem was taken seriously, but it was not until December, 1916, that the proposal that the post of battalion Signal Officer should be re-created was seriously put forward. Discussion went on for months, during which time many battalions anticipated the decision of the higher command. Finally, in December, 1917, the necessary amendment was made to the War Establishment and the new appointments, which by now had become general, were officially recognized. A marked increase in the efficiency of battalion signals was the immediate result wherever officers were appointed, while another important side-issue of the decision was the re-opening of a channel through which a supply of most efficient junior officers flowed into the Signal Service.

It may be said of the temporary signal officer that, the nearer the front fine he gained his early experience, the better was his signal practice and the more use was he in an emergency. Quite the most efficient officer for forward signal work was the battalion signal officer who had seen service and had then been sent home for a six months course of technical training. In future wars, this method of choice might with good results be made more general and a much smaller percentage of totally inexperienced material taken into the commissioned ranks of the Signal Service. An ideal forward Signal Service would be that officered by men who represented the pick, either of the battalion signal officers, or of the rank and file of the forward signal units. In such men will be found a knowledge of the conditions of modern war which has been gained at first hand combined with a working knowledge of signal practice as modified by these conditions. A comparatively short course of training would serve to equip them to grasp the more technical work they would necessarily have to supervise as they rose in the Service and were appointed to more exalted posts further to the rear. On the other hand, the man chosen without experience of war, however well trained technically, is an uncertain factor when exposed to the soul-testing and nerve- racking experiences which he cannot fail to meet when he takes up his duties in the fighting area. He may do untold damage both to the lives and the morale of his unit before he becomes acclimatized. He may not; but the risk is there.

To certain technical posts in the rear, however, this argument does not apply. Technique will here often be of paramount importance, and to fill such posts no better men could be employed than those who have spent their lives grappling with problems similar to those they would have to face in the Army. Thus, for such posts, sometimes at Corps, more often at Army, still more frequently on the Lines of Communication, personnel with the necessary technical experience,, but little military knowledge, would often be admirably suited.

Another effect of the high percentage of casualties amongst battalion signallers and Brigade sections was the rejuvenation of the Divisional Signal Schools. Whenever a Division was in rest or holding a quiet part of the fine, sometimes even when the Division itself was battling in the full tide of war, the Divisional Signal School was established at some convenient village or hutment camp well to the rear. Here, artillery and infantry signallers were trained in visual and in new types of forward signalling appliances. Special attention was given to improving the speed of forward signalling. Great care was taken in teaching the men the principles and practice of telephone and fullerphone working. All men were taught also to repair the simpler type of lines — "D5," "D3," "D2" and "D1" — and to lay them in the safest and most efficient manner to suit various tactical situations. Here, also, the new recruits — partially trained in the Depots at home, but totally unfamiliar with service conditions — were given a final polish before taking up their work in the field. Usually an officer for the Signal School was found from the Divisional Signal Company, either by appointing one of the supernumerary officers allowed to these companies by a wise policy, or by using a Brigade section officer whose place would be taken by a supernumerary. The latter, of course, might be expected to give the best results. During these long years of trench warfare the Divisional Signal Schools played a predominant part in maintaining at a high level the efficiency of the signal communications within the Divisions. They were never officially recognized, but their importance cannot be over-rated, and the need for them is almost certain to recur under similar conditions. There is a certain type of training which is best carried out, indeed, it can only be efficiently undertaken, within reach of the atmosphere of the fighting line. The Division is the fighting formation, and training within the Division can hardly be replaced.


A principle which must be recognized throughout in modern warfare is that no means of signalling within the area of heavy shelling is infallible. All are liable to break down or become non-effective from one reason or another. The deepest buried cables yet achieved can be severed by the direct hit of an 8-inch shell.[7] Visual is dependent on atmospheric conditions and is often impossible through smoke and dust. Wireless sets may have their masts and antennae destroyed by shell fire. Pigeons cannot normally be used at night.[8] The acme of good signalling organization is the combined use of all these means, with the runner as a last resource. A runner service is a slow and expensive means of intercommunication. Especially is this so in the case of the type of attack at present under consideration when comparatively long distances have to be covered. Where distances were greater than 500 yards, and where mounted orderlies and motor cyclists could not be employed, runners were worked in relays and relay posts were arranged at 200 to 500 yards apart according to the ground.[9] The runner relay posts were frequently made coincident with lineman's posts and, in many cases, the runner was taught to keep his eyes open and to mend obvious breaks in the cables on his way back after delivering a message. Runners during the Somme battles became differentiated in the main into two classes: — (1) officer's personal runners who always accompanied the officers into action; (2) general runners who were at the disposal of the signal officer or sergeant and who were attached to companies or to battalion and Brigade Signal Officers.

The first qualification of a good runner was bravery. He took his life in his hand day after day, and many times a day, as he jogged to and fro between front line and company headquarters, between company, battalion and Brigade headquarters, or between relay posts. Sooner or later, almost certainly, a machine-gun or rifle bullet, or a shell would claim him as a victim. The danger attending the duty was accompanied by none of the generous heat engendered by the excitement of an action and the prospect of a hand-to-hand encounter with the enemy. Under no particular eye, with nothing but a sense of duty to prevent him from seeking the comparative shelter of the nearest shell-hole, only the most courageous men could be expected to traverse the barrage zone many times a day in the course of his duty. Every battalion and company commander, every Brigadier, counted his runners among the best of all his men.


It is now necessary to discuss one of the features of the Somme battles which probably gave the Signal Service more trouble than any other. This was the conversion of the initial successes of the general attacks, not, as was hoped, into mobile operations, but into slowly-moving siege warfare. In the first few hours of such a general attack events might move comparatively swiftly. Sooner or later, as the element of surprise ceased to have effect and the enemy accumulated reserves and guns, the initial impetus would be slowed down although the advance was not brought to a standstill. The Signal Service was then faced with all the inconveniences and difficulties of an intensely raging battle and yet with such comparative stability that the Staff claimed and expected to receive all the conveniences which had come to be admitted as their right during stationary warfare.

Labour was not available for the forward extension of the buried system. Some makeshift was required which would enable lines to be carried forward with, at any rate, a fair prospect of success. Various methods were tried and the most successful was found to be the laying of cables in spade-wide trenches, one or two feet deep, which gave protection against anything except a direct hit or a splinter from directly overhead.

Occasionally a system of German cable trenches could be utilized, and these had the additional advantage that they led straight between German dug-outs or strong points which could be used as our own headquarters. Shallow buried cable was also tried but it had serious disadvantages. Cables covered with earth were very little more immune from damage than those in open trenches, while they were much more difficult to repair. The principal trouble with the open trench was found to be that all units were liable to use the trenches of the command line system to protect their own lines. Gradually the confusion along such routes almost vied with that which had nearly rained the line system in 1915. The identification of the original lines could be secured by means of seizing them with spun yarn to stakes in one corner of the bottom of the trench and by careful labelling every 50 yards or so. Induction troubles, however, were not so easily overcome. In such an advance, neither transport nor cable was available in sufficient quantity to permit of all circuits being made metallic. It was recognized, too, that in a swiftly changing situation the danger from overhearing was much reduced. The enemy was losing ground and had to keep his listening sets well back, while several such sets had been captured or destroyed. Induction trouble was, however, a great drawback to these open trenches and prevented them from becoming really popular. From every other point of view they were easily the best substitute for the deep buries, for, in addition to the other advantages already detailed, they gave a certain measure of protection, and therefore of confidence, to the lineman responsible for the maintenance of the routes. In the special situation described it was to such open trenches that the credit for the retention of a fairly complicated system must be attributed. As soon as practicable, labour was obtained from the General Staff and the deep buries were pushed forward. With the completion of the latter to a well-protected cable-head near battalion headquarters, the situation could once again be considered normal until the next advance.

It was in such situations as the above that wireless found its principal opportunity in the Somme offensive. Attempts were made in some formations to push forward wireless sets with assaulting parties, but without success. A wireless station required a carrying party of several men and an efficient system for the interchange of charged and discharged accumulators. Under the conditions of the battles this difficulty usually proved insurmountable. Party after party was dispersed — sometimes destroyed — by shell fire or machine-gun fire, and finally, it was definitely ordered that wireless was not to be carried forward during an attack.

When the situation had settled down, attempts were made to use wireless to communicate with special isolated positions where communication was liable to be cut off for days at a time. Sometimes the wireless station also failed, maintenance of the aerial being impossible in the overwhelming shellfire to which the posts were subjected. In other cases, however, better results were obtained and, on occasion, wireless was the only means of communication left, and important tactical messages were dealt with by the set.

At, and in rear of Brigade headquarters, the wireless sets although easily kept through were little used in normal times, as the deep buried cables were seldom broken. When, however, Brigade and battalion headquarters had moved forward off this system, they were often invaluable. It is significant, however, that it was reported that enemy jamming stations immediately ceased operations when they realized that a British ground station was endeavouring to send a message of technical importance. This is particularly interesting in view of the evidence given by captured German documents concerning the German attitude towards field wireless.

As late as the spring of 1917, Field-Marshal Hindenburg was strongly against the use of field wireless of any description. He attributed his victory at Tannenberg entirely to the fact that during the whole of the action he was able to overhear and follow the plans of the Russian higher command as transmitted by wireless to the fighting formations. He was greatly in fear of similar indiscretions and considered the function of wireless should be the interception of information which might be obtained from a less careful enemy wireless service. His objections were overruled, and the Germans soon developed field wireless to a considerable extent, but this attitude bears a distinct resemblance to that of the British Divisional and Brigade Staffs, and such an uninformed dislike to wireless was a potent hindrance in the path of its development.

On the whole, we may say of wireless on the Somme that its use was the exception rather than the rule. It was not until the next year that forward wireless achieved a measure of popularity.

Before completing the recital of the lessons of the Somme battles, a few words should be said of certain new methods of signalling which were at that time on trial or in the experimental stage. The appliances referred to are the power buzzer and amplifier, the message-carrying rocket and bomb, and various acoustic forms of apparatus.

The last method referred to has, for the present, dropped out of consideration, except in the one specialized instance of the Klaxon horn which since its great success in the Somme battles has become a standard method of signalling from aeroplanes. Indeed, the consideration of this type of signalling instrument may be despatched at once with the single remark that the intention was to make use of the Morse code as interpreted by two horns of differing tones, one being chosen to represent the dot and the other the dash. The instrument was based on a French device and was tried with success on the Somme up to a distance of 1,500 yards. It had many disadvantages, however. The signals were liable to be drowned by the noise of bombardment. They were audible to any enemy near the sending and receiving station and could therefore only be used for code messages. The conditions under which the apparatus might be of sufficient use to justify its existence were so few that the experiments were not persisted in.

The history of the development of the power buzzer and amplifier will be reserved for consideration under the position battles of 1917, when this instrument was first used with really decisive success and on a large scale. Its possibilities in action were first shown during the Somme battles, but its exploitation as a practical means of bridging heavily shelled zones in the forward area properly belongs to a later period of the history of signals.

The use of message-carrying rockets and bombs, on the other hand, never became general throughout the Army and may be dealt with once and for all in the present connection. The use of rockets as light signals had been universal from the beginning of trench warfare. In the Somme battles,[10] S.O.S. signals were practically confined to different-coloured rockets. So general did their use become that the Germans went to the trouble of copying the type of rocket in use in the British Army with a view to the confusion of our artillery. The display of rockets from both sides of the line became to a greater and greater extent the most picturesque feature of the night until stationary warfare ceased. One particular application to signals was the use of rockets as an acknowledgment to D.D.D.D. visual messages. This method was suggested and employed by some units, but was accompanied by disadvantages which prevented its general adoption.

It was early suggested that rockets might be employed for carrying messages and lines. The first specialized line-carrying projectiles were those used by the personnel of the forward wireless stations for erecting wireless aerials. A piece of light line was attached to a "dummy" rifle grenade which was fired above the projection over which it was desired to pass the wire. An insulator and aerial wire were then attached and the aerial drawn up into position. The device was successful and was standardized, rifle grenades without detonators being issued as part of the usual equipment of trench wireless stations. From this to the line-carrying rocket was one step only, and the latter was given extensive trial but never with much success. Cases are on record where lines were laid this way, but sufficient accuracy could not be obtained and the experiments were dropped.[11]

The evolution of the message-carrying rocket was more successful. Proposals were first made from First Army based on the personal experience of the Lieutenant-General commanding one of its Corps, who had used a blank rifle grenade successfully for this purpose. Later, in November, 1915, the 3rd Corps brought to notice a German rifle flare with a range of 500 yards. It was suggested that a similar flare might be devised with a recess in the weighted end. Into this recess might be put a message written on pigeon paper and rolled up in a cylinder.

The rifle grenade was, however, soon ruled out of the question on account of the difficulty of identifying and locating the message- carrying projectile, and rockets accompanied by a trail of smoke and burning a bright flare on alighting were substituted. Experiments were continued throughout 1916 — a side line being experiments with message-carrying bombs which proved to be of no practical value. In September, 1917, two types of the "Wynn" message-carrying rocket were adopted; one long-range rocket with a radius of action of 2,300 yards, the other, a lighter type for short ranges, 15,000 were ordered at once and a monthly supply of 6,000 arranged for.

In 1918 supply was made in fair numbers and the rockets were advertised by carefully-arranged demonstrations carried out by the O.'s C. Divisional Signal Companies before Brigade and battalion commanders. The demonstrations were carefully stage-managed and uniformly successful and the new rockets were used to some extent in the position battles which preceded the advances of the autumn of 1918. Difficulties of supply, however, prevented sufficient practices being carried out to enable all ranks to become familiar with them, and this precluded their employment on a large scale. In individual cases they were made great use of, the extent of their popularity being largely dependent on the particular experience of individual battalions.


  1. Of course with adequate safeguards against leakage of information.
  2. It was not until much later in the war that attempts were made to train pigeons specially for night flying. The French intercommunication service were the pioneers in the new departure, but after the return from Italy, Second Army signals also experimented with a special loft. The birds were kept in red light and were trained at night. Excellent results were obtained in practice flights, the only light required being a powerful one with its rays projected on to the special landing stage. This light could of course be screened from the sight of the enemy's aerial observers. By the time the training of the birds was completed, the last advance had commenced and they were therefore not actually flown during an attack.
  3. A signalling shutter with slats after the fashion of a Venetian blind.
  4. One Corps alone in the Thiepval sector lost several hundred horses through their becoming bogged in impassable country.
  5. Examples occurred, for instance, when signallers of the forward parties were obliged to take to their rifles and fight their way forward or even to capture the positions they would afterwards use as a signal office.
  6. In some cases, discs of tin were sewed on the backs of the men's tunics, but the device did not prove successful and is in any case somewhat outside the scope of Signal Service activity.
  7. On several occasions six foot buries were cut by "dud" shells which penetrated to a depth of 8 or 9 ft. Delay action shells intended for the destruction of dug-outs or other counter-sunk works would, of course, have a similar, but much more devastating effect.
  8. See note, page 138.
  9. It should be noted that the opinion of experienced battalion signal officers and runners is that it is better to have through runs, as relay posts are impossible to supervise, sometimes unreliable and difficult to ration. Relay posts under half a mile apart are also very extravagant of men. When installed under pressure of circumstances they should be temporary and closed as soon as possible.
  10. Trials took place in 1915 with the idea of the use of coloured rockets by the Cavalry in the event of a break-through at Loos.
  11. An attempt was also made to carry listening post earth connections across "No Man's Land" by means of trench mortar bombs but without success.

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