command of forward signals from the uncontrolled battalion, through brigade, division, and corps, to army. Concurrently with this, the commanders of signal units became staff officers i.e., representatives of the command itself instead of simple executants. 1
In the meantime, the idea of the central signal route in each formation having been launched, it was natural that other means of signalling should at once tend to concentrate along these routes, with their protected test-points and signal offices. Econ- omy and greater trustworthiness at once followed, and in the battle of the Somme, 1916, when the British army first carried out a great offensive from prepared positions, the central signal route, running from front to rear of each divisional sector and reinforced with all possible means of intercommunication, was attempted as a definite policy. The line system was carried for- ward in 6-ft. buries to a cablchead in, or even in advance of, the front line. Cable detachments were organized and held in readi- ness to extend the lines. Runners and despatch riders were organized in relay posts along the cable route. Wireless and power buzzer sets were also erected in convenient dugouts close to cablehead and the forward communication centres. By this concentration of means along one line, and by an all-round train- ing which made the personnel to some extent interchangeable, economy of personnel, elasticity of procedure, and a minimum of casualties were ensured.
In the more extended offensives of 1917, this principle was carried still further and reinforced by instructions issued by G.H. Q., which required the headquarters of formations to give the signal officers concerned early and detailed information as to projected operations, forbade movements of headquarters with- out good cause, and laid down other important points of principle.
The culmination of position warfare thus arrived in the spring of 1918 to find the signal service quite equal to the calls made upon it. At G.H. Q. and on the lines of communication were ade- quate office staffs and a sufficient number of permanent line and airline construction companies and sections. The bases, camps, depots, and stores concerned with the administration and supply of a great army were served by army telegraph and telephone routes. Maintenance. parties at all offices dealt with ordinary day-to-day repairs; breakdown gangs at central positions were in readiness to cope with the catastrophic breaks due to bombing and long range shelling. At G.H.Q. itself powerful wireless stations formed the initial link of a chain line which reached right forward to the front line; other stations were engaged in intercepting the German wireless; and a headquarters wireless staff coordinated the activities of the Intelligence stations scat- tered throughout the rear army zone. Here, also, was the nerve centre of the whole signal service in France the directorate of signals the staff which formulated the policy of the service, supervised its organization and working, and allocated the incoming reinforcements of men and material.
The basis of the signal system of the army was again a telegraph and telephone network which was built up on a " chessboard " or " grid " system, that is with front-to-rear routes and routes trans- verse to the front, spaced at regular intervals and with the main signal offices and test-points at the junction of the two. Until late in 1917 the approved theory was to make the line system approxi- mate as nearly as possible to the perfect " grid " with as few and as heavy routes as possible. With the increase in the amount of long- range shelling and bombing which was a marked feature of early 1918, this principle required considerable modification. Two or three parallel routes usually took the place of the single heavy route of each corps or army area, and all routes were diverted to a much greater extent in order to avoid centres likely to be bombed or shelled.
The constitution and working of the army signal company per- haps more nearly reflected the conditions of position warfare than did that of any other. A telegraph construction company, a light railway signal company, and airline sections were the chief elements of the construction personnel, though there were also cable sections for connecting up isolated units at any time, and dealing with emer- gency connexions in battle. Here, also, were wireless light motor sections, mainly employed on supervisory duties, but like the G.H.Q.
1 Strictly, this applies only to corps and army headquarters, though before the war ended, it was the unofficial practice in most divisions also.
wireless, available to take their place in the chain of intercommunica- tion in the event of the failure of the lines. Most of the traffic was dealt with by wheatstone, duplex, and simplex telegraphy, and the magneto telephone, wireless telegraphy being chiefly utilized to assist and police the more forward stations. The chief signal officer of the army had also to coordinate the signal schemes of the forma- tions in his army, and under his command were the area detach- ments whose permanent duty was the maintenance of the buried cable in the army area.
In the area of a corps the forward position of which was liable to frequent shelling the main routes were still permanent line and airline and the construction personnel consisted in the main of air- line detachments. In addition, corps cable sections were available for emergency cable-laying, for loan to overworked divisions (a fre- quent case), for artillery signal work, or for running spurs to iso- lated offices off the main airline routes. The personnel of the corps cable sections was also often employed to supervise labour parties in the construction of the buried cable system, though, as above men- tioned, maintenance personnel was provided through the army area detachments. The corps wireless section, while principally con- cerned with store distribution and supervisory and police duties, was more intimately connected with the tactical employment of wireless than was that of the army. Particularly in battle periods, the corps-directing station was frequently obliged to step in and assist its less powerful subordinates to attract the attention of other stations or to rebuke stations using undue power or contravening priority regulations, besides policing procedure and listening for occasional windfalls from forward German stations.
Lastly, the chief signal officer of the corps had to supervise and control the signal communications of the heavy artillery. For this purpose a special section had been added to his company, but this was altogether inadequate and in practice the whole energy of one corps cable section was usually devoted to the construction and maintenance of artillery lines. These corps units were differentiated in principle from the area detachments by the fact that they pos- sessed sufficient transport to enable them to move forward while con- tinuing their work. In all adaptations of the signal units of forma- tions below army the essential characteristic of mobility was re- spected. Those elements t>f the service which required to be special- ized to areas were embodied almost entirely in the army company, others being organized so as to be able to move as integers.
This principle of mobility naturally applied with still more force to divisional signal companies. Even when position warfare seemed to be most definitely established the retention of its horse transport by the divisional company was insisted upon, in spite of the extra work entailed by the care of horses upon a personnel fully occupied with its technical work. This insistence had its reward in the long run, for mobility regained all its old importance on March 21 1918 and retained it to the end of the war.
The original divisional signal company in 1914 consisted of the following elements three " brigade sections " (in principle serving the infantry brigades), each of a telephone detachment and a squad of signallers, a " headquarters section " consisting of a small office staff and a few signallers and despatch riders, and a " No. I section " of three cable detachments, each of which was capable of laying 10 m. of cable and carrying three offices. By the spring of 1918 the " headquarters section " had been enlarged in every branch, and " No. I section " had been increased to four detachments to cater for the field artillery headquarters; but the " brigade sections," though much overworked, had remained practically unchanged. To these three original elements, however, others had been added. A small section, similar to a " brigade section," was serving with every field artillery brigade in the division. The reorganization of the machine-gun service in Feb. 1918 added another small section to serve the divisional machine-gun unit. The extension of wireless telegraphy to the division had invelved the addition of sufficient personnel to man a " Wilson " and three " 50- watt " sets and a charging set for accumulators. In addition, men were attached from brigades to man six power buzzers and their corresponding receivers, and to eke out the still undermanned visual detachments.
Forward of battalion headquarters, the direct responsibility of the divisional personnel ceased and, in battalions and batteries, signal communications were built and maintained by regimental signallers. Occasions occurred when the requirements of these units could be accommodated on the central system, but these were exceptional. Usually their signallers were fully occupied with the lines and with visual communication between the front line and their headquarters. The means at their disposal were light cable lines and enamelled wire with D3 buzzer telephones; heliograph, lamp, flag, 2 disc, or shutter; pigeon, messenger dog, message-carrying rocket and runner. In the case of power buzzer, pigeon, and messen- ger dog, communication was usually roundabout, via brigade, divi- sion and even corps headquarters; in the case of other appliances, direct touch from front line to company headquarters and from company to battalion headquarters was the rule.
The most interesting portion of the evolutionary history of signal communication in the war finishes with this period, and the story
2 The artillery still used both Morse and semaphore ; infantry signallers at this stage of the war were trained in Morse only.
