The Signal Service in the European War of 1914 to 1918 – Chapter 14

«--	The Signal Service in the European War of 1914 to 1918 Chapter XIV	--»
Chapter XIII		Chapter XV

Chapter XIV.

SIGNALS IN RETREAT.

SYNOPSIS.

The General Situation in March, igi8. — Buried Cable Absent or Incomplete on the Critical Front. — Poled Cable and Airline Between Divisions and Brigades. — Visual and Wireless Relied Upon to a Great Extent. — Too Little Attention Paid to the Signal System of the Rear Defence Lines. — The Opening of the Attack. — Fog prevents Observation and Visual Signalling. — Line System Destroyed within a Few Minutes. — Two Main Phases of the Retreat. — The Fighting Retreat through Prepared Defences. — Arras and the North. — Safe Buries and No Retreat. — The Situation South of Arras. — Excellent German Long-Range Artillery Preparation. — Loss of Forward Signalling Apparatus and Signallers. — Importance of Wireless and P.B. and A.; Visual and Message-carrying Agencies in the First Phase. — Formation of a Rear Emergency Carrier-pigeon Service. — The Second Phase: The General Retreat. — Extent of the Withdrawal. — Characteristics of the Retreat. — General Signal Policy. — The Divisional Route. — A Contrast in Staff Methods and the Effect on Signals. — The Need for Concentration of Headquarters. — Chief Difficulties Encountered. — Hurried Movements. — Laterals. — Congestion of Traffic. — Supply. — Fining Up at Dumps. — Destruction of Routes. — Lessons Learnt during the Retreat. — Line Signalling in Retreat. — Permanent Lines and Ground Cables. — Effect of Tanks, Traffic and Horse Lines. — Cables Used. — Instruments Used. — Emergency "Grid" of Ground Cable. — Wireless. — Practice in Stepping Up Required. — Supply of Accumulators. — Interception. — Rise in Importance of Wireless. — Visual. — Differences in Procedure. — Message-carrying Agencies. — Battalion Communication.— Loss of Stores. — The Lys Retreat. — The 9th Corps in the Marne Retreat. — Signal Personnel in the Fighting Line. — Carey's Force. — The Retreat Reflected in Rear Signals. — Special Instructions for Future Similar Emergencies. — Special Training for Mobile Warfare.

The campaigning season of 1918 found the Allied Armies resting on the line which had been the boundary of their gains of the 1917 offensives and awaiting the expected German attacks which would be the logical outcome of the general war situation. The collapse of Russia during the autumn of 1917, and the immense reserves which Germany was thereby enabled to transfer from the Eastern to the Western front, precluded the Allied Command from entertaining the thought of a sustained offensive on a large scale, and at the same time made certain of a great attack on the part of the Germans. The first three months of the year were, therefore, spent in attempts to consolidate the defence system on the entire British and French front. On the front held by the British Army the situation had been still further complicated by the fact that 28 miles had been recently taken over from the French.

From all points of view the situation was not too favourable. The losses sustained in the offensives of the previous year, combined with the importance of retaining all ground gained in the north, made it impossible to hold the southern portion of the long front in any strength. Divisions were widely spaced and Divisional areas were in some cases as much as 7,000 yards broad. A severe strain was thus thrown upon the whole Army, and the Signal Service was not exempt from the ill effects of a dangerous situation.

The very success of the battles of 1917 had carried the forward formations far in advance of the safe buried cable systems to the west of the Somme battle area. Behind the armies — in the event of a retreat — were the battlefields themselves where cross-country traffic was practically impossible.

Across this devastated area signal communication was by a few main routes strung out along the roads over which the materials for their construction had been transported with difficulty. These routes, even in the quiescent times which preceded the main attack, were already suffering severely from the attentions of the enemy's long-range guns and from his long-distance bombing planes. Yet these troubles were but a foretaste of what was to come.

In the battle zone itself frantic efforts were being made to improve the signal communication of the three main defence lines. Here, however, the Signal Service was much hampered, both by the competition of other branches of the Army for the use of the available infantry working parties, and by the shortage of cable. The latter difficulty was almost masked by the former. Labour was required for the perfection of defences, for the building of light railways, for the digging of water mains, for a thousand other purposes. Buried cable routes advanced very slowly, indeed, and in the majority of cases had only reached Brigade headquarters by March 21st, the fateful date when the opening of a fresh campaign ushered in a new variety of experience for the Army generally.

Forward of Brigade, in many cases, only a few pairs could be hastily put through. In other cases, the forward portion only had been completed, and the bury stopped several hundred yards in front of Brigade headquarters and was continued backwards by poled cable or open wire routes. In yet other cases, and this applied especially to the portion just taken over from the French, no bury was available at all. It was only in the neighbourhood of Arras and further to the north, where the advances had not been of such depth and where the signal situation had been more stable, that a safe buried cable system enabled the signal officer to look forward to the future with comparative confidence.

Everywhere south of this the buried system was, at best, partial and, at worst, absent altogether. When it was incomplete or missing, the line system was partly of ground or poled cable, partly of open wire routes which frequently reached as far forward as Brigade headquarters. Between Brigade and Divisional headquarters, strangely enough, the area which had previously been par excellence, the natural habitat of the bury, was almost everywhere spanned by these comparatively inefficient substitutes.

Previous experience had been sufficiently decisive to make all signal personnel absolutely certain that, when the attack came, the first thing that would happen would be the failure of line communication all along the front. No one, however, could have foreseen the completeness with which that prophecy would come true. The work of the German artillery was to be far in advance of anything it had previously achieved.

It was quite clear that more reliance than had usually been the case must be placed upon alternative means of communication. Comprehensive visual schemes were arranged right throughout the length and breadth of the unusually large Divisional sectors. The wireless chain was made as complete as the available apparatus would permit. The third week in March saw the latter preparations as complete as was possible, but the immaturity of the buried cable system left in the signal officers' minds an uneasy feeling which was to be justified only too completely by events.

Every available means of communication had been made use of to the utmost, but a relatively insecure system was the best result attained, and this was to be made even more inadequate than it might have been by the extremely unfavourable weather conditions. There is, perhaps, one direction — though one direction only — in which the signal preparation can be subjected to legitimate criticism after the event. If anything, it appears that too much attention had been paid to the forward communications in the outpost zone which was intended to be lightly held and which, it was anticipated, would be overrun by the enemy in any persistent attack. The communications of this zone — visual, runners, forward wireless, and even telephone, were very thorough and left neither time nor material to ensure a like thorough system in the second and third lines of defence where it was to be expected that the main stand of a sorely-pressed Army would be made. In the event, this proved to be a serious weakness in the signal dispositions, but it cannot be criticized too harshly under the circumstances. All previous experience had gone to show that forward signals were of paramount importance. In previous battles, also, the presence of a safe buried system had been the rule, and a reasonable amount of communication in rear of Brigade headquarters in stationary warfare had become, under these conditions, almost a matter of course. It was an unfortunate concatenation of circumstances which caused the balance of importance to shift from front to rear at the very time that the incompleteness of the buried cable system rendered the rear communications peculiarly vulnerable.

The enemy bombardment commenced at 5 a.m. on March 21st, and the whole British front from Arras to its southern limit on the Oise river was subjected to a shell storm which exceeded all previous experience. For four hours shells of every size, containing high explosive and every variety of deadly or disabling gas, were poured upon the thin line of British forward troops. At the same time the areas as far as 15,000 yards behind the front line were searched by high velocity guns firing by the map on all important headquarters, cross-roads, battery positions, strong points, etc., that had been previously registered by the enemy. British and German lines alike were shrouded in a dense ground mist which made observation impossible. Thickened by the smoke and dust from the bombardment, the fog soon became impenetrable, and all preparation to meet the imminent attack had to be made by guess work. Within the first few minutes practically all the forward open routes were out of action, whole sections being blown away in some cases.

Within a few minutes of the commencement of the bombardment, a thoroughly complete — though recognizedly unsafe — signal system had been reduced to a partial haphazard medley of such ground cable as had survived, such wireless stations as had escaped extinction, and a few power buzzer and amplifier stations in strong points and at formation headquarters. Many of the visual stations had been flattened out of existence by direct hits during the earliest stages of the bombardment. The remainder were ready to work, but rendered quite useless by the ground mist, reinforced as it was by the smoke from the shells, the dust raised by the bombardment, and the large quantities of gas which were a marked feature of the shelling. It was on this half-destroyed system that forward signal officers had to rely for intercommunication during the forthcoming attack; it was over various arteries of this system that the first reports from the infantry began to come back, as the garrisons of post after post discovered the presence of the German infantry, often to find themselves completely surrounded before they could signal back for assistance.

In the struggle which followed, and which continued until the 3rd and 5th British Armies had been pressed back upon their final defence positions covering Amiens, there are two main phages to be distinguished as far as the Signal Service is concerned. The first of these was the initial fighting in the prepared positions of the 1st, 2nd and 3rd defence systems: the second was the hurried retreat, with occasional pauses and with continual rearguard actions, which ended at the position finally taken up before Amiens and behind the Somme. Following upon the two main phases, again, came an entirely different but less interesting period when the situation had been stabilized and the retreat was stopped. Here, position warfare once more set in and a fresh signal system was built up which resembled those of the previous periods of position warfare with a few modifications due partly to the evolution of new methods and partly to the after-effects of the previous retreat.

A general review of signal practice in the first and most intense phase of the March battle again shows that this in its turn presented two distinct aspects. Signal practice differed markedly on the front to the south of Arras from that opposite Arras itself and to the north, which was outside the scope of the original attack. The latter — being of least interest and less intimately associated with the second or semi-mobile phase of the retreat — may be referred to shortly first.

On March 21st, the British line opposite Arras was subjected to a certain amount of bombardment, but no attack took place. It was not until the success of the attack further to the south seemed assured, that the German higher command decided to extend the area affected by the attack, and fresh Divisions were launched against the troops manning the Arras and Vimy defences.

The problem facing the local signal officer was here relatively easy. The difference in his favour lay mainly in the fact that this area had only been slightly affected by the advances of the summer and autumn of 1917 and had not been affected at all by the German retreat that took place in March of that year. Arras was alike a valued possession and a desired objective of attack. Its importance and its nearness to the line were potent causes both of the strengthening of the British defences and of a like consolidation of the German lines so that the enemy might not be forced back from a position whence it seemed to him likely that he might successfully envelop the town. The defences round Arras had thus been for both sides a bastion on which the opposing lines had pivoted, and were destined to pivot once again, in the fluctuating fortunes of the long years of war.

The buried cable which underlay the town and penetrated the caves and tunnels of the defences was still within the sphere where its common everyday use was practicable and, indeed, essential. It had, therefore, been kept in good order and formed a secure basis for a safe signal system which presented none of the anomalies of those of the Corps and Divisions further to the south.

Once more the attacks on Arras failed and in the recoil our outpost lines were re-established, or even in places pushed further forward than before. The history of the signals of this portion of the action would only be a repetition of the story of signal practice in the position warfare of 1917. It is better to pass on to the consideration of the more difficult problems and more interesting lessons which were being solved and learnt in the south, where by this time the retreat had become general.

South of Arras, the opening phase of the battle was marked by an almost complete destruction of Division-Brigade signal communications, while those between Division and Corps were interrupted over a, considerable portion of the front. A characteristic of the short but furious preparation had been the exceedingly efficient work of the German long-range artillery who were shooting by the map on all the mam communication features and likely concentration areas as far back as Corps headquarters. The practice made was truly extraordinary and numerous examples could be cited from the experience of the Signal Service alone. On several occasions direct hits were secured on junction poles; main telegraph routes were brought down wholesale in blocks several hundred yards long; Divisional signal offices were "bracketed," or even struck by shells and the personnel forced to take refuge in dug-outs; the roads up which supplies had to pass were rendered impassable by direct hits or destroyed transport, or were blocked by the ruins of houses.

During the remainder of the 21st, while the British infantry, supported by the artillery as well as was possible without adequate observation or signal communication, were endeavouring to retain their hold upon the second and third lines of defence, the rear telegraph and telephone system had gone to pieces almost beyond repair. The sole surviving remnants were ground cable hastily run out by cable detachments, or patched up circuits on those permanent routes which were less thoroughly destroyed.

One or two circuits were kept through intermittently on the front of the majority of Divisions, but even with six men spread out on each mile of route it was found impossible to expect communication between Division and Brigade for more than half of the time.

Forward of Brigade headquarters, the signal situation depended largely upon the presence of absence of buries. Where buries were in existence, working was continuous even over routes the test points of which had been overrun by the enemy. Where buries were absent, the ground and trench cable had shared the fate of the Hues further back, and intercommunication between the various isolated posts of the first defence system was either non-existent or was carried on by means of alternative methods of signalling which did not need lines.

As the British forces were gradually forced back off their forward defences or surrounded and isolated in strong points and separate trenches, the various signal dug-outs were also ceded to the enemy and gradually the whole forward signal system passed into their hands. Where possible, instruments, terminal boards, and exchanges were destroyed, but a great deal of undamaged material must have been captured. It may be said that, forward of battalion headquarters practically no signalling apparatus was saved, while a large number of signallers, both of the battalions and batteries, and of the Brigade forward parties, were involved in the debacle and were either killed or captured.

The comparative failure of the line system once more — as in the Cambrai battle, though here for a different reason — caused the various alternative means of intercommunication to assume a greater importance than usual. In this particular case, also, the range of means which could be employed with any hope of success was still further restricted by the dense fog which made visual completely out of the question until well on in the afternoon. During the critical hours of the morning of the 21st, power buzzer forward of Brigades, and wireless between Brigades and Divisions were the mainstay of the intercommunication system. Until 8.30 p.m., many hours after they had been surrounded, wireless and power buzzer messages were received from isolated strongholds which were invested by the enemy. Such messages afforded valuable information to the higher command as to the situation in the forward positions which were still holding out. Prisoners since repatriated have told how the wireless sets, by enabling them to keep touch with their more fortunate comrades, put heart into defenders who felt they were in a hopeless position and encouraged them to fight to the last. The stubborn resistance of these isolated parties did much to embarrass the German advance and thus to steady the retreat of the shattered Divisions endeavouring to withstand the impetuous rush of immensely superior forces. Anything which encouraged their morale and helped them to hold out was of vital importance and, from this point of view alone, the work of the forward wireless stations was of incalculable value.

Further to the rear, such wireless sets as survived, though their aerials were shot away again and again, formed in nearly all cases a valuable auxiliary method of communication and, in many Divisions, were the sole reliable link with the Brigades until the second phase of the battle commenced. Not only did the stations in the battle zone itself do good work, but the personnel of stations on the flanks came to the rescue of their more hard-pressed comrades and assisted to dispose of urgent messages when touch could not be obtained directly to the rear. Already wireless was proving itself invaluable. In the days which were to come its importance was to be demonstrated to a still greater extent.

It was not until the afternoon that visual became possible, but when the mist rose it was used to a great extent. Many of the forward visual stations had been destroyed by direct hits during the bombardment, but between Brigade and Division in the second and third line positions heliograph was used with success and the Lucas lamp proved its usefulness again and again.

It was the first time that visual had been given a great opportunity on the Divisional-Brigade line of communication and in this and the succeeding days long distance work was somewhat hampered by the reduction that had taken place in the number of heliographs issued to forward troops. Their place was, however, fairly successfully filled by the Lucas lamp which proved an efficient substitute over most of the distances involved. Bearing in mind the usual European climate with its large proportion of overcast weather, there is no doubt that, in spite of such isolated cases as the present, the withdrawal of the heliograph was more than justified by the saving in transport effected and by the greater simplicity rendered possible in the training of reinforcements.

Message-carrying agencies played a less important part than usual in the phase at present under consideration. In the early hours, the fog was so dense that runners could not be used with great success while the attack was so overwhelming that the whole available rifle strength of the front line troops was required to reinforce the firing line. Later, as the various posts realized that they were cut off, parties were told off to cut their way through the investing enemy troops and carry news of their comrades who were remaining to fight to the death at their posts. In some cases, the survivors of such parties made their way through the enveloping Germans; in others, isolated runners succeeded in finding their way to the rear formation headquarters. More often, the first news of the success of the German attack received by the higher command was given by the advance of bodies of the enemy on the headquarters themselves.

Between Divisions and Brigades motor cyclists did good work under great difficulties. Men were blown off their machines by the blast of shells falling near them and resumed their journeys immediately they had righted their cycles. Cases occurred of motor cyclists and machines being buried, dug out, and then carrying on as if nothing had happened. During the next few days the motor cyclist despatch rider was to experience a few short but crowded hours which recalled the early days of 1914. He was once more to be, on occasion, the sole means of intercommunication. The descendants of the men who made good in the retreat of 1914 proved now that they could worthily uphold the traditions which had heretofore been the only reminder of a glorious past which seemed to have been replaced permanently by a humdrum routine.

The pigeon service was perhaps more thoroughly disorganized by the fresh turn taken by the war than any other branch of the Signal Service. As the retreat gained in depth and accelerated in velocity, the so-called mobile lofts proved to be relatively very immobile. In many cases, the necessary horses to carry out their removal were not available, while in others congestion along the roads prevented the early retirements of motor lofts. In all, 40 horse-drawn and motor mobile lofts fell into the enemy's hands. Of these, most had been destroyed by fire and the majority of the birds they contained had been killed. In no single case during the present retreat was a mobile loft captured complete with its birds.

The credit for the relative smallness of the losses is due to the head of the carrier pigeon service, who had foreseen the emergency. Twelve months before the events which momentarily crippled the forward organization on this front, orders had been issued for the destruction of lofts and birds in the very circumstances which had now arisen. These orders were conscientiously carried out by the N.C.O.'s in charge of the lofts, and the enemy can have reaped little advantage from those stations that did fall into his hands.

During the first few hours of the battle, many pigeons were released with S.O.S. messages, but the results were considerably more patchy than usual. In the most favourable cases, birds homed quickly, were received at their lofts as in normal times, and the messages were despatched by hand or phone to the headquarters to which the loft was attached. In some cases, where the telephone lines were down, corporals in charge of pigeon lofts acted on their own initiative and improvised a bicycle service between the loft and the headquarters until one or other was forced to withdraw. In less favourable circumstances, there were several stages of a complicated process where things might go wrong. Sometimes the birds were lost in the fog, and in one or two Divisions, though many birds were despatched, no single one reached the loft. In other cases, the loft had been destroyed by shell-fire, evacuated, or burned, before the arrival of birds which had been retained by their holders as an emergency means of communication. In yet others, the messages were received in safety at the loft, but the pigeon corporal was unable to find a headquarters which had precipitately retired.

At times, carrier pigeons once more proved to be a useful supplementary method of communication, but on the whole their success was less complete than usual, while the loss of birds was so heavy that the service was crippled to a certain extent. Immediate steps were taken to secure more birds and reorganize, but it was some little time before the effect of these fresh efforts could make itself felt. In the meantime, both from the new aspect assumed by the fighting, and from the shortage of birds, the pigeon was largely to drop out of place as a regular means of forward intercommunication on the critical front.

An interesting result of the success of the German offensive was seen in the organization of a two-way pigeon service by both French and British Signal Services between Paris, the French G.Q.G., the British G.H.Q., and the headquarters of the various French Armies. Although never actually brought into use, the service was organized and worked effectively. Had the German success carried the enemy far across the Marne and driven a wedge between the British and French Armies, the presence of this auxiliary pigeon service would have been invaluable. As it is, it is of interest to observe that in their practice flights, birds flying between G.H.Q. at Montreuil and the allied headquarters in Paris were flying part of the way over territory in German occupation.

The main lesson learnt by the pigeon service in the German retreat was that, although the majority of the lofts should be as close as possible to Divisional headquarters, some should be kept further back towards the limit of the birds' flight. In the event of a successful advance by the enemy, these lofts would remain safe throughout the fighting in the rear defence systems. Once a retreat becomes general, the pigeon naturally drops out as a means of intercommunication, and is not missed to any great extent. During the hard battling through rear defence zones, however, their services would be particularly valuable and future pigeon service organizers might well bear this in mind.

With the penetration of the third defence system, the second phase of the retreat was ushered in. Hurled out of their last prepared positions, the British Armies were forced to withdraw behind the line of the Somme, where a fresh attempt was made to stem the German flood of invasion. The withdrawal was successfully accomplished, but the enemy pressed hard upon the heels of the retreating British infantry and the Somme line was penetrated almost as soon as it was taken up. A further retreat to an "Army" line along the Roye-Albert road was then undertaken and, after a short pause, this line was turned at its northern extremity where the Somme runs east and west. The final stage of the retreat ended with the British Armies holding the outer Amiens defences and a line running south from there. Here the situation was more stable and the final stages of the 1918 battle of the Somme were waged with varying fortune, but without decisive result, along this last hastily-prepared defence zone. It was here that on April 5th the first stage of the great German offensive was stayed and normal trench warfare resumed its sway.

The greatest depth of the retreat was from 20 to 25 miles, and the fortunes of the Divisions engaged varied with their distance from the pivot point to the east of Arras. One Division established five headquarters in five miles in six days, another as many as 14 headquarters in 16 miles in three days. The experience of others varied within these limits. Signal practice of course was largely dependent upon the depth and speed of the retreat. There were, however, in this second phase of the battle, certain definite features which were characteristic of the warfare and which were faithfully reflected in the type of signal system adopted.

The first phase of the battle had been characterized by insufficient preparation, by overwhelming shell-fire, and by intensive fighting in well-prepared positions. The result had been a modified position warfare signal system whose success was only partial. In the second phase now under consideration, on the other hand, the characteristics were negligible shell-lire and comparatively rapid retrograde movement, varied by occasional rearguard actions of fiercer intensity when an approximation to position warfare once more set in.

The characteristics of the signal system differed accordingly and the general policy adopted under force of circumstances was that of the central route down the Divisional front. The success of the signal communication of different formations varied considerably and was even more a reflection of the methods of the General Staff than of the efficiency of the signal officer. The shortcomings of a demoralized staff were at once apparent in the inefficiency of the system. In the one case where a Corps headquarters vanished suddenly to reappear in a French area, no communications existed between the Corps and its Divisions, because lines were not available on the French system. In another case, where a Corps handled the unprecedented number of 13 Divisions, line communication was never lost between Division and Corps, because the retreat was conducted on a well-considered policy. Divisions moved to new headquarters as ordered by the Corps and found at least one metallic circuit waiting for them on arrival. Corps airline sections and cable sections were employed with forethought and skill to serve the needs of subordinate formations. Not only was line communication available, but it was reinforced and assisted by a wireless chain which was of the greatest help.

On no previous occasion was the effect of Staff methods on signals and signals on Staff methods more clearly seen. When the Corps controlled the route followed by Divisions and Divisions that followed by their Brigades, the subordinate formations fell back along permanent lines which had been reconstructed and put through for their use, or, better still, along the uprights of a "grid" of cables which would give them communication to rear and flank alike. When Divisions were left to retire at their own sweet will and Brigadiers followed the routes that most appealed to their fancy, the signal officer was faced with an impossible problem and his cable and wireless detachments were tired out by attempts to run lines to places where he guessed the Staff might be.

On more than one occasion a wireless or cable party was exposed to imminent risk of capture through proceeding in the course of their duty to lay a line to or erect a station at a place where the Staff of a Brigade had been directed to take up their headquarters but to which they had not gone. On one occasion, a wireless officer who had billeted himself and erected his station was aroused from sleep by the tidings that the enemy were entering the village, and he escaped with his detachment by minutes only.

Another lesson learnt early in the retreat was the necessity of grouping artillery and infantry Brigades on the same route and at the same "communication centres." Where this policy was not followed, bad shooting inevitably resulted and the troops of the rearguard were sometimes exposed to the shells of their own artillery through the impossibility of quickly communicating range corrections. When artillery and infantry Brigades worked in close liaison along one central route, there was no difficulty in improvising circuits or laying cables. Communication by line was good and the retreat well-ordered.

The chief difficulties in a hurried retreat were the number of moves, of headquarters, the provision of lateral lines, the congestion of traffic, and the replenishment of cable and stores. The first of these was inevitable to a great extent, but the trouble could be minimised by careful attention to organization, by co-ordination from Corps headquarters, and by the exercise of forethought. Movements of Corps headquarters twice in one day appear unnecessary, but such movements occurred. Divisions moved more frequently than they need have done, and lack of instruction as to direction of retreat resulted on more than one occasion in a swinging movement which brought the lines of communication, and consequently the mam signal route, right across the exposed flank of the Division.

The question of the provision of lateral lines was difficult, and, under the circumstances of the retreat, often impossible of solution. Information from the flank was frequently of more importance than from the rear, yet it was usually not available. This could have been overcome only by the exercise of co-ordination by the higher command. If individual Divisions had been kept advised of the direction in which their neighbours were retreating, the problem in keeping intermittent lateral signal communication would have presented little difficulty to the signal companies.

Congestion of traffic much affected the movements of the cable detachments and it may be laid down as an axiom that fast cable in such a retreat will not normally exceed a speed of one mile an hour. Roads crowded with retreating transport and with first fine transport bringing up supplies, presented an almost insuperable obstacle to the harassed leaders of the cable detachments. Cross-country journeys were almost impossible — certainly impossible to a six-horsed team in the devastated Somme area across which the greater portion of the retreat took place. The arrival of an enemy bombing plane was even hailed on one occasion as an opportune incident. Bombs were dropped and the road was cleared of traffic by a helpful combination of anxious drivers and unmanageable horses. The cable detachment was able to make unexpected progress and the occurrence was recorded in the report of its commander as an unmixed blessing.

The question of supply also bristled with difficulties when the zone formerly occupied by the Armies in their battle positions was left behind. As the cable and airline sections retreated through towns and villages which had formerly contained signal headquarters and stores, they filled up in turn with cable and other essentials. Single cable was taken in preference to twisted, for once again earthed lines had come to the fore and the importance of length of lines overrode any consideration of enemy overhearing. As the Divisions retreated off the Corps areas, however, the cable dumps became few and far between and the greatest economy had to be exercised. A cable famine was well in sight, and, indeed, in some Divisions, in existence, by the time the Amiens line was reached.

As far as possible Army lines were utilized by Corps, then by Divisions, and finally by Brigades and Battalions. Line communication was never attempted forward of battalion and only by about half of the formations forward of brigade. Finally, as the area was ceded to the enemy. Divisional personnel were instructed to complete the destruction of those circuits which the Corps linemen had left intact for their use. Here a distinct difficulty was encountered. Divisional signal companies were equipped neither with tools nor with explosives for destroying permanent routes. The best that could be done was to cut the wires and, whenever time permitted, this was carried out.

The different measure of success achieved by different formations very clearly pointed the principal lessons of the retreat as regards signal policy. The main principles laid down in S.S. 191 for an advance held good equally for a retreat. The direction taken should be controlled by the highest formation concerned. The movements of headquarters should be decided as early as possible and thoroughly advertised to superior, subordinate and lateral formations. Divisions Brigades, and battalions should be bunched as much as possible along one main Corps route. If this is not practicable, work should be concentrated along one route in each Division. In order to ensure efficient liaison between Artillery and Infantry headquarters, it proved essential that they should camp together or within easy reach of each other by orderly. This was difficult to insist upon, as the tendency was for the artillery Group or Brigade commander to live amongst his guns. It was, however, important, and was perhaps the most essential of all the lessons learnt.

Apart from general questions of signal policy it is interesting to review the effect of the retreat on each of the different means of signalling employed. First and foremost in rank of importance, as usual, was a line system modified considerably by the reversion to semi-mobile warfare. The measure of line communication achieved depended upon the utilization of the existing permanent routes and. the use of the cable wagons. A certain amount of cross country work was still carried out by hand or by the use of one-horsed carts improvised from a hand barrow carried in the front half of a limber. By far the greater proportion of the main line system, however, was made up either of improvised circuits along the permanent lines, or of ground cable laid from the wagons of the cable sections.

The permanent routes within nine miles of the original front line had been much destroyed, but beyond this distance less damage had been done. The enemy's long-range guns could not be moved forward quickly and his bombing planes had such a large area to cover that a great proportion of the routes escaped. The troubles that arose in the utilization of the system by the subordinate formations were usually of a technical nature. Permanent records had not been kept at all test-poles and test-boxes and the confusion left in the offices after their hurried evacuation made it difficult to test out individual pairs. In addition, the Divisional linemen were not used to dealing with heavy routes and it was often found to be less trouble to lay fresh cables than to utilize the partially damaged permanent routes. In some case the topmost circuits were reconstructed. In other cases, the whole of 12 or more pairs would be bunched and used as a single conductor. The permanent routes were, however, used to a much greater extent by the retreating Corps. Corps linemen knew more about these lines and were better able to .sort out an office previously unknown to them. A Corps looking after 13 Divisions, seven Divisional Artilleries, and five Brigades of R.G.A., could not afford to lay cable to all its units. Both airline sections were fully employed testing out the circuits required, while the two cable sections ran short spurs from the nearest test-poles on the permanent lines to the proposed headquarters to which the formations were instructed to retreat. The task of the signal units was simplified to some extent by the adoption of a system of advanced exchanges for groups of Divisions and Brigades of R.G.A. For making stray connections, motor cyclist linemen were found invaluable and the judicious use of two or three of these men saved an immense amount of time and labour to the remainder of the maintenance personnel.

Within the Divisions, on the other hand, the cable wagon was the main means of establishing intercommunication. It was discovered. that ground cable could be maintained in all cases except under barrage fire. Intercommunication by cable was the rule between Divisions and Brigades, and, with a little more organization, could have been used to a greater extent than it was between Brigades and Battalions. Speedy and unexpected moves and poor Staff work often resulted in interruptions of considerable duration, but when the situation had again cleared and the strayed Brigades or Divisions had been once more located, the cable wagons quickly reconstructed the Division — Brigade line system.

On occasions short lengths of cable were laid at a canter, but, as already mentioned, one mile an hour was a good average. Cable detachments worked devotedly and spent themselves to the utmost in the endeavour to give good and continuous service. Here, again, success varied with the method of employment, and cases occurred where Divisions relegated their cable detachments to the rear early in the retreat with drastic consequences to their intercommunication system. Others used them too recklessly in the first few days of rapid retreat and found they had no cable left to create a line system for their next stand. An old lesson was re-learnt when it was found that it was not advisable to lay lines at all when movement was fast unless a halt of 24 hours was likely. Judicious employment was essential to the success of the cable detachments, but in the majority of cases good results were obtained.

The cable parties were often much hampered in their work by lack of reliable information. Cases occurred constantly of a thousand or more yards of cable being laid, of orders being rescinded, and the cable dragged back and again "pulled" out in a different direction. Every such case added an unnecessary increment to a fatigue which was cumulative in its effect. Lines were laid under long-range infantry fire and under machine-gun fire, and many casualties occurred among the personnel of the sections. No department of the Signal Service did better work in these critical days than the cable sections and none justified to a greater extent the training in mobile warfare which had been carried out as part of the normal routine in every "resting" period.

Tanks and traffic were a source of damage to the lines and efficient liaison with the former was of course impossible. It was not possible under the circumstances to prepare "tank" crossings, and they would have been of little use, had they been built, since their presence could not have been notified in time. The use of ground, rather than poled cable overcame this trouble to a great extent, and, for the rest, it had to be accepted as one of the evils of the situation. The establishment of horse-lines along the main route of retreat was also a fruitful source of trouble but this also could not be avoided.

The cables in general use were single "D5" and "D1," though "D3," "D2," and twisted "D5" were also used to some extent. The need for the reinstalment of single cable in the equipment of the cable wagons was proved, and this reform was carried out immediately after the situation settled down.

In the rear of Brigades, ringing telephone with superimposed sounder represented the last word in efficient communication. Where lines were not well balanced, telephones were used for the transmission of phonograms as well as for speech. Forward of Brigades, message traffic was by fullerphone or by the ubiquitous "D3" telephone, which was still the last resort of the Signal officer in difficult situations. The large exchanges which had come into use during position warfare proved to be a nuisance in the mobile lighting which had now set in, and a strong recommendation for smaller exchanges was one result of the new phase. Many units made up small offices for use in temporary communication centres and in some cases the instruments of these were rigidly fixed to a table for facility of transport.

In effect, the possibility of good line communication even in a rapid retreat was demonstrated as surely as was the danger of the telephone habit which had gained so great a hold upon the Staff. The ideal line system during a retreat was shown to be a slender "grid" of ground cable laid out by the Corps cable sections along a carefully thought-out route and taken over by Divisions which were falling back in orderly manner by fore-ordained stages through headquarters selected by the Corps. One or two circuits only would be available for each Division, but these should suffice to carry all essential communication. As in the lesser retreats in the Cambrai sector, it was amply proved that the greater proportion of telephone conversation was unnecessary and might well be replaced by concise operation messages, carefully worded to prevent possibility of misconception.

It was quite possible to maintain such a skeleton network in spite of shelling and traffic, but a heavy line system was out of the question. When the situation stabilized, as it did, first on the Army line and then upon the G.H.Q. reserve line in front of Amiens, the line system could be extended forward and reinforced in the rear. This was actually achieved on the front of most Divisions and a good example is afforded by the system of one Division, in particular, on the Army line.

In this Division, signal touch was maintained for three days by ground cable to each battalion in the line. Five minutes before the time when retreat became essential, orders were given to all battalion commanders over the telephone, the fines were disconnected, and the offices removed. The Division continued its march to the rear, with communication by D.R., and orderly. On arrival at the G.H.Q. line, the line system was once more built up and remained in existence until it was replaced by the normal buried system of position warfare.

273 In spite of the comparative success with which line communication was kept up, wireless telegraphy again became an essential method of signalling. The two factors which still limited its usefulness were jamming — both from our own and from enemy stations — and the necessity for cipher or code. Interference by enemy stations was very pronounced and, indeed, the Germans appeared to be relying principally upon their wireless stations for forward work. Jamming from neighbouring British stations was also serious, but was remedied to a great extent by strict control from Corps and Army headquarters. Where this control was not enforced, the system broke down; where it was properly exercised, on the other hand, wireless proved invaluable. The figures of wireless traffic during these few days had never been approached before. Stations of individual Divisions were dealing with as many as l00 to 120 tactical messages a day and this result was achieved in spite of the partial survival of cipher regulations. These latter were, however, swept away to a great extent, as they always were in anything approaching mobile warfare. Where they were rigidly insisted upon by a punctilious Staff, the wireless stations of the formation were, of course, crippled in their activities and their value was much reduced.

The mobility of the situation affected the Corps and Army stations for the first time and the need for practice in stepping-up procedure as far back as Army headquarters was at once seen. The stations of the higher formations were not habituated to mobile warfare and their absence from the scene of activity for periods of varying length invalidated the whole system to a certain extent.

A great advance in tactical organization was made by the issue of Wilson sets as local directing stations for Divisions, and, where this was done, much improvement in the Divisional scheme at once took place. In some Divisions, the question of transport was overcome by the use of the car of O.C. Signals for the transport of the Divisional directing station, and of pack horses for the stations with Brigades. In the majority of cases, however, the Brigade stations were moved about by hand and it was only by herculean efforts on the part of the personnel of the stations that they were kept in action at all.

The available "loop" sets were very useful, and, as one of the lessons of the battles, a much more general issue of these forward sets was advocated. They were frequently invaluable for maintaining touch between Brigade and battalion headquarters and the transport problem was less serious where such light stations were concerned. The supply of accumulators to sets of all types was one of the difficulties which had to be overcome and the absence of the signal box car authorized, but not yet issued to Divisions, was especially felt in this connection. Many officers solved the problem by devoting a limber to this duty; in other cases recourse was had to small dumps of accumulators left in well-marked spots along the line of retreat. By one means or another, most Divisions managed to arrange for a sufficient supply, and the wireless sets were in use during the greater part of the retirement, while power buzzers and amplifiers made their transitory appearance whenever the situation became more stable.

In many cases, the wireless stations fulfilled a valuable role by intercepting messages from all neighbouring formations and providing a precis for the digestion of the General Staff. On one occasion, at least, a German concentration was broken up through the interception of the orders by a station in the area affected. The message was translated at once and conveyed to the Staff, who ordered artillery fire to be directed upon the concentration area with the result that the attack never developed.

It was in keeping touch with flank formations that wireless, from its very nature, was most useful. Lateral fines were often impossible, but the portable wireless stations could establish touch, as well to right and left, as to the rear. It was to this method of signalling more than to any other that the Staff looked for information as to what their neighbours were doing. So long as the flank wireless stations were in commission there was little fear of a break-through taking place to right or left without information reaching the Divisional Commander in time to permit him to organize a defensive flank or to hasten his retreat.

Casualties to sets were very numerous, especially when attempts were being made to hold up the German advance on a definite line. At one time, one Division had every set out of action with injuries caused by enemy shell fire. During the second phase of the retreat, casualties to wireless personnel were not so common as those among the cable detachments. Many instances of individual bravery were recorded, however, and the personnel behaved well and rose fully to the exigencies of the situation. The one great chance of justifying wireless appeared to have arisen and few opportunities were lost. Army wireless telegraphy came out of the March retreat holding an entirely different place in the opinion of the signal officer and the General Staff from that which it occupied before the battle.

It was now recognised that in mobile warfare this method of signalling had to be reckoned with as an essential means of communication. The formation without its wireless sets was nearly as crippled as that without the means of creating a line system. The time was soon coming when wireless was to prove its use equally well in the advance. When that had been done it had risen to its legitimate place in army economy as an essential means of signalling. Its early struggles for recognition had been justified by the result.

With the exception of the early hours of the morning during the first day or two of the retreat, conditions for visual were good and this means of signalling was extensively used. Forward of battalion headquarters it formed, as usual, the only alternative to runners. In rear of battalion headquarters it was frequently used to establish communication between the more erratic Brigade and Divisional headquarters. As in the case of wireless, the chief opportunity for visual arose when there was lack of co-ordination between retreating formations. A well co-ordinated retreat could be accommodated on an improvised line system; formations retreating at random could only obtain touch through the medium of their wireless sets, or by utilizing favourable opportunities for the establishment of visual stations. For lateral communication, especially, visual was invaluable. In the rear areas the Lucas lamp was the main means used, with the heliograph as substitute on isolated occasions. Forward, flags were used a great deal, but the folding shutter attached to a bayonet fixed on the end of the signaller's rifle was the favourite method. Pocket electric torches were again used with success over short distances.

In one Division, visual was the sole means available between Division and Brigade for three days, and 50 messages a day were disposed of by the visual stations. This was exceptional, however, and implied a breakdown in other methods of intercommunication. One difficulty experienced as a result of the general use of visual was the exposure of certain small differences in the procedure used by different units. This could be traced directly to imperfections and ambiguities in the Training Manual of Signalling which had led instructors at different schools of training to adopt their own interpretation of the obscure points. In a normal chain of visual signalling where the units of a Division worked usually among themselves, these peculiarities had not been particularly noticeable, but the general use of visual for lateral signalling at once betrayed them and pointed out the necessity for a more precisely worded manual.

The employment of message-carrying agencies was perhaps most marked by the rise in importance of the motor cyclist despatch rider and the elimination of the pigeon. Motor cyclists were all worked exceptionally hard and were often called upon to carry out portions of their journeys under rifle or machine-gun fire. Frequently the location of the units they were bound for was uncertain, but considerable ingenuity was displayed in unearthing headquarters. Many despatch riders did valuable reconnaissance work in addition to their normal duties. The men worked with little rest and less food and in the more hurried hours of the retreat were of vital importance. They were reinforced where possible by mounted orderlies but the latter were too few to be of maximum use.

In some formations, both motor cyclists and mounted orderlies were worked with a lack of discrimination which resulted in undue fatigue and sometimes in the delay of urgent despatches. Despatch riders were sometimes used to find subordinate units who should have notified their whereabouts to the nearest signal office. Here the importance of the paragraphs in Section 20 of S.S. 191 were strongly emphasized. Unless units gave their assistance in establishing a system of orderlies between themselves and the signal office during the halt for the night, it was impossible for the Signal Service to undertake delivery of more than a few of the more urgent messages. The supply of signal orderlies was totally inadequate for the purpose, for these men were only intended for the delivery of messages to the offices of the local formation Staff. This lesson, also, should have been learnt from the mobile fighting in 1914, but the command of the majority of units had altered entirely since those days.

Forward of battalion headquarters, the experiences of the retreat all pointed towards the formation of one main chain of intercommunication on each battalion front. Here, as further to the rear, the main lesson learned was the need for economy of personnel and for concentration along one predetermined route. Thus, and thus only, could fairly uninterrupted intercommunication be achieved. It was seen that, if this system of concentration was adopted in position warfare, then transition to mobile conditions was easy and could be carried out with the least loss of material and expenditure of manpower. The same policy should be carried out successively back to Brigade, Division, and to Corps. When open warfare supervened, the concentration of all efforts on one single Divisional route would then be easily accomplished.

The vital importance of the axiom, "One formation, one signal route" cannot be overestimated, for this principle, well carried out, provides the acme of signal communication of forces on the move. The application of signal methods in an advance to the situations of a retreat is not too obvious, but the resemblance which should exist between the signal systems in both types of warfare cannot be too strongly insisted upon. A comparison of a series of diagrams of signal systems in the retreats of the summer and the advance of the autumn of 1918 would show this very well. A comparison of similar diagrams of the hypothetical systems the signal officers concerned would now employ in similar situations in the light of their experience of that year would probably illustrate my point immeasurably better. It is unfortunate that financial considerations will not permit of the inclusion of such series in the present volume.

The loss of stores which accompanied the retreat was to be deplored, but was inevitable. It had been foreseen to a great extent, but circumstances were such that it could not have been avoided. Preparations for a withdrawal were to be deprecated on many grounds, and particularly on account of the effect they were bound to have upon the morale of the troops concerned. The loss of trench signal stores was the lesser of two evils and was necessarily acquiesced in. Actually, much of the Army signal equipment was saved, being thrown hastily unto railway trucks and despatched back to Abbeville. The stores that remained were largely used by the subordinate formations in their retreat and were the one factor which made possible the maintenance of the line system. Large quantities, again, were destroyed by the last signal units to pass them; more still were annihilated by our own and the enemy artillery. Considerable amounts did, however, pass into the enemy's hands intact, and evidence of this was afforded during the advances of the following autumn, by the amount of British field cable being used by the Germans. The effect of the loss and destruction of signal stores was severely felt in the ensuing summer, but, on the whole, the situation might have been much worse.

On April 5th, the German offensive on the Somme front came to an end and the exhausted troops were left to recover themselves while the scene of action shifted quickly to the north. On April 7th, a bombardment, which rivalled in intensity that of March 21st, broke out along the whole front from Lens to Armentieres. The attack which followed presented in its main features a marked resemblance to the advance in March, but was not on anything like so important a scale. Only 42 as opposed to 73 German Divisions were engaged: the front was much shorter, and the advance in no case exceeded a depth of ten miles. The action also was slower and the advances more spasmodic, except upon the front held by the Portuguese Corps. It was here that the pigeon service lost a fixed loft, that at Lacouture being captured complete with birds.

Thick fog was, once more, a characteristic of the calm weather of the day of the initial attack. All the elements were again favourable to a surprise and the enemy made appreciable progress on the first day of the battle. In the days which followed, many of the tired Divisions just recovering from their experiences on the Somme were thrown in to stem the onrush of the German hordes. The signal companies were thus given an opportunity of putting into practice the experience they had gained in the previous battle and a very efficient signal system was usually the result. In its main features it followed the lines indicated earlier in this chapter, (pp. 257 — 275).

The same isolated instances of power buzzer-amplifier communication to surrounded strong points was again recorded. The station at La Basse Ville, in particular, was still working when the rear station was forced to withdraw out of range. The less general nature of the retreat enabled twisted cable to be used in preference to single cable. Pigeons were of greater use, and in one case a service of birds was kept up, although the loft to which they worked was within 500 yards of the front line. It was found, however, that pigeons were inclined to be shell-shy when alighting in heavily shelled areas.

Wireless, on account of the slight nature of the withdrawal, still suffered under cipher restrictions and operators who had become used to sending "in clear" messages during the great retreat were betrayed into indiscretions in consequence of that experience, and in some cases disciplinary action was necessary. The first work carried out on the line system was the replacement of airline by cable. In front, the buries were giving good service, and when the retreat carried the Divisions off them, the ground cable once more formed a good basis for a reliable intercommunication system. The principle of the Divisional route was by now firmly established and the chief lesson of the short Lys battle was confirmation of the fact that correct deductions had been drawn from the experience of the previous month.

The failure to penetrate the northern portion of the British front brought to a close the enemy offensives against the British Armies, but on May 27th the 9th Corps was involved in a very similar battle, where 28 German Divisions were hurled against the 6th French Army in their positions on the line of the Aisne.

The report of the A.D. Signals on the signal practice in this battle, where a solitary British Corps was isolated amidst French formations, contains several paragraphs of peculiar interest. Comment was made particularly on the weakness of the French system of arbitrarily fixing the dug-outs of the buried cable system and then leading in to headquarters with poled cables. When the initial bombardment opened, all these aerial connections were blown to scraps and much valuable personnel was lost in attempts to replace them. The buries themselves remained through, but full use could not be made of them because of the frequent interruptions in the leading-in cables.

The waste of material and labour in installing a telephone system forward of battalion headquarters was also once more emphasised. The network of cables which had been built up with much care and trouble was blown away in a few minutes. During quiet times such a system could be dispensed with; during a battle of any intensity it was worse than useless.

One feature of the battle was the absence for several days of rear intercommunication except by despatch rider. Owing to the peculiar disposition of the Army headquarters, all the main rear routes ran for many miles parallel with the front that the enemy were attacking. Moreover, practically all the routes were concentrated at one point in a town which was an obvious target for the enemy's heavy artillery. The result was that, for a long period after the first few hours of the battle, the Corps was practically isolated. It was not until the headquarters of formations had retreated on to an excellent system of locality telephone exchanges in the rear areas that the absence of shelling, which here as in previous retreats distinguished the mobile phase of the battle, permitted of general telephone communication to the rear.

Forward of Corps headquarters, the communication to Divisions and Corps H.A. depended entirely upon hop-pole routes and these served excellently until the mobile phase of the retreat set in. Then, again, recourse was had to ground cable laid by the Corps along the routes by which the Divisions were directed to retreat. As in the Lys retreat, in which this Corps played a prominent part, each Corps airline section was divided up into three improvised detachments which were used for laying cable. By means of these detachments three main cable routes were laid which were looped in at intervals to nodal points and were used throughout by the retreating Divisions.

As in the previous battles, the necessity for more lateral communication was seen. The retreat was very hurried and signal touch from front to rear was all that could be maintained. Alternative methods were useful, but were only very partially successful. Wireless was used during the early hours of the battle, but the destruction of numerous stations and the capture of others soon practically eliminated this means of signalling. Pigeons also were of great use during the first few hours of the retreat, but when the withdrawal became more hurried, all lofts were evacuated or destroyed.

The withdrawal was so hasty and equipment was so scarce that visual was of little use. Aeroplane liaison was, however, better than it had ever been before. The Divisional dropping grounds were used continually and almost all the messages contained information of value. Motor cyclists once more came into their own and the observation was made that the attachment of a liaison officer to collate the incidental information collected by these men might have been extremely valuable to the higher command.

The casualties of the signal units, already decimated by the previous fighting, were once more very high. The following table which gives

280 the establishments of the units and the percentage of casualties suffered by each in these few days of lighting will give some idea of the wastage which the Signal Service as a whole had suffered during each of the three retreats referred to.

Table VII
Percentage Casualties of Signal Units of the 9th Corps During the Aisne Retreat.
Unit.	Casualties.		Establishment.		Percentage.
	Officers.	Men.	Officers.	Men.
50th Div Sig. Co.	6	110	11	272	41%
25th Div. Sig. Co.	—	10			4%
21st Div. Sig. Co.	—	22			8%
8th Div. Sig. Co.	3	90			33%
9th Corps Sig. Co.	—	25	1	97	26%

The signal units were in urgent need of a prolonged period of rest to enable them to refit and to absorb the partially trained reinforcements who now formed some considerable portion of the strength of the forward sections. This they were to have when a new period of stationary warfare enabled them to prepare for the victory that was to crown the efforts of the Allies.

One aspect of the recent fighting about which little has been said is the absorption into the firing line of signal personnel which took place to an unparalleled extent during the retreat. The fighting formations were strained to the uttermost to cope with the emergencies which arose one after another. In order to man reserve lines of trenches, officers were deputed to collect stragglers and non-combatants of every grade, arm them as best they could, and line them up to stop the enemy rush. In the early stages of the Lys battle, for instance, one battery alone lost 15 orderlies conveying important messages in less than one hour, and it seemed farcical to attempt to keep up intercommunication by runner at all. Signal personnel apart from orderlies were usually exempt from such forlorn hopes by virtue of the distinguishing blue and white band which vouched for their importance at their legitimate work. There were, however, exceptions to the rule, and there may arrive a time in any battle when the technical value of the signaller is outweighed by his potential value as a rifleman or bomber.

It should be remembered, however, that he is a signaller first and an infantry soldier only a long way afterwards. His technical training has fitted him for specific duties for which the ordinary infantryman has not been trained: while his technical duties have not fitted him for employment as a marksman and have made him totally unused to the bayonet. He is also likely to know nothing of the intricacies and ways of bombs.

It is very seldom that a justifiable case can be made out for the deliberate employment of Signal Service personnel in the firing line. When such a case is made out, however, or, when the signaller is caught up in the rush and hurry of a rapid retreat, experience has shown that he will rise to the occasion and fight with a resolution and intelligence which will help to make up for his lack of skill.

Examples of the use of Signal Service personnel as infantry occurred on all three retreats, and in the Aisne battle, especially, the Brigade sections of more than one Division acted as riflemen through a strenuous action. The classical instance occurred, however, in the retreat from the Somme when a mixed force of details which contained a proportion of signallers, wireless operators, linemen and telegraph operators, was hastily organized and thrown into the reserve line of trenches before Amiens. For five days, from March 29th to April 2nd, these amateur infantrymen held their position under intermittent bombardment from artillery and low-flying aeroplanes.

As a general rule, the special effects of the retreats on the dispositions of the Signal Service stopped short at the final positions taken up by the headquarters of the Armies involved. A certain amount of telescoping of the routes between Army headquarters and G.H.Q. naturally occurred, and emergency measures were prepared for a general removal of the dumps and Depots which were threatened by the German advance.

Perhaps the most interesting result of the situation was the closing of the school at Abbeville, the men and material being held in readiness for use as reinforcements to the Corps engaged in the fighting. The increased importance of wireless in particular made imperative the need for the immediate replacement of losses both of personnel and instruments. An innovation which should be noticed as part of the emergency signal system, was the establishment of a C.W. motor wireless section at Abbeville, to act as an alternative means of intercommunication between the O.C. Troops, Abbeville district, and G.H.Q., where similar sets had been installed.

Two sequels to the retreat also deserve mention. The first of these was the issue of elaborate instructions for the destruction of signal stores and communications in the event of another serious retirement. All instruments and stores were to be destroyed. Test-boxes on buried routes were to be blown up. All open routes were to be broken down as Corps headquarters retreated past them, with the exception of the two upper wires. As the routes became spare, further damage was to be done. Stays were to be cut, poles — especially junction poles — cut or blown down, and terminal poles and roof standards were to be thoroughly smashed. When destruction was not possible, hidden faults were to be introduced with a view to making a hurried use of the routes by the enemy impossible. Fortunately these precautions were never required by ourselves, although similar instructions were very thoroughly carried out by the enemy in his retreat in the autumn of the same year.

A further direct result of the experiences of the retreat was the special training ordered for all forward signal units during the next few months of quiet. One cable detachment was kept continually at cable wagon exercise whenever possible. Wireless personnel were practised at quick installation of stations and at packing trials. Divisional and Brigade visual personnel were exercised as much as possible on moving station schemes. Half an hour's physical exercise per day was aimed at for the headquarter staff of signal units. Finally, route marches became a most important part of the normal routine during resting periods. By some or all of these means the physique of the signal personnel of Corps and Division was improved and the mobility of the units increased. By the time the advance commenced most signal units were able to carry out long marches and work through long and fatiguing days without being overtired. The policy of concentrating on training for mobile warfare was entirely justified by results.

The success of the Signal Service in adapting a rigid system to the mobile conditions of the retreat, was in itself a triumph, both for the organisers of the forward system and policy and for the personnel whose wholehearted devotion enabled the best results to be obtained from the dispositions made. The crystallisation of the opinion of the General Staff, whose needs signals are primarily intended to serve, is seen in the following quotation from the official despatch describing this incident of the war:—:"During the long periods of active fighting the strain placed upon the Signal Service was immense. The frequent changes of headquarters and the shifting of the line entailed constant labour, frequently attended with great danger, in the maintenance of communications; while the exigencies of the battle on more than one occasion brought the personnel of signal units into the firing fine. The Signal Service met the calls made upon it in a manner wholly admirable, and the efficient performance of its duties was of incalculable value."

Footnotes

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