O.E.D: Signal [1871] = To communicate or make known by signalling; to notify or announce by signal(s).



Good communications between the commander and his troops, and vice versa, has always been a sine qua non in armies of all nationalities. Many a victory has been won through its successful implementation, at the crucial moment, and others lost for the lack of it. The expression 'The fog of war' (Clausewitz) aptly describes the situation when communications do break down for whatever reason. 

The British did not have a separate Corps of Signals in the Great War: it was agreed that an independent unit would be formed in 1918, but for various administrative reasons it was delayed until 1920. 

At the outbreak of war in August 1914 all the British Armies signalling/ intercommunication requirements were met by the Royal Engineers Signal Services (RESS) that was formed in 1908. Previously, in 1870, the responsibility for all military communications was officially given to the Telegraph Troop, of the Royal Engineers. 

The communication services that were available to the British Expeditionary Force (BEF) in late 1914 can be summarised as follows: 

  • Visual signalling. (Long used by the army in the form of fire-beacons, semaphore, and the heliograph).
  • Telegraphy. (Duplex [two-way] telegraphy; a relatively new invention dating from 1870).
  • Telephone. (But initially only at the senior command level).
  • Dispatch Rider services. (The use of motorcycle dispatch riders had just begun in 1914).
  • Runners. (Battalion level message carriers - often susceptible to high casualty rates).
  • Wireless. (Wireless sets - nowadays called radios - were also being introduced in 1914, but their bulky and fragile nature made portability difficult).
  • Pigeons. (Front Line coded message carriers from late 1914).
  • Military Postal Service.

All these services except the battalion runners, and some of the visual signallers, were routinely provided by the RESS.

By the end of the Great War in 1918, the RESS had become provider of a whole range of communications for the British Army. In the process, it had developed a reputation for using vanguard technology, and good reliability, as the British Army's need for efficient communication links became ever more crucial to the management and administration on the Western Front.

The evolution of the RESS on the Western Front

1914: The RESS was by no means omnipotent in 1914: each BEF artillery battery and infantry battalion has it own signallers and means of communication; other independent systems existed at the highest command levels. RESS's area of dominance only began at the brigade level so a certain degree of chaos was inevitable whenever the two systems met or overlapped. No-where was this more evident than in the telegraph/telephone system, which was the prime line of intercommunication in 1914, and of increasing importance. Turf battles between the competitive signallers were not unknown, neither was the filching of essential signals material.

In effect, many vital military intercommunications depended unduly on a not very reliable French civil telephone system and it, and the BEF's own system, was far too vulnerable to interception by very efficient and determined German Listening Squads. These squads were particularly active and effective close to the Front Line. British telegraph/telephone security systems were notoriously lax at this time: whole tactical plans were read out in plain speech over the telephone and listened to by the ever alert Germans.

The move into more static trench warfare at the end of 1914, brought about inevitable, and essential, changes to the BEF's signalling modus operandi. Training Courses were organised for signallers at the Division and Brigade level and a successful attempt was made to bring in the free-booting infantry battalion signallers into a single uniform intercommunications operation; the artillery proved to be more resistant to the loss of its dedicated signallers.

New military telephone systems were also slowly being introduced across the Western Front.

Meanwhile, BEF HQ impressed on the more senior of the officer corps the need for the proper and economic use of the telegraph/telephone system to protect it from overload. Also, the officer corps was repeatedly reminded it was absolutely essential that there be an improvement in the level of security by strict adherence to the necessary security protocols. Certain senior officers tended to treat the system as their personal facility and were loath to change their imperious and careless ways.

Whilst rather primitive and cumbersome wireless sets were available using, Morse Code, the British Army could not find any practical application for wireless at this stage of the War and it was not until the final months of war in 1918 that wireless sets became widely deployed at the battalion level.

However, the Royal Flying Corps (RFC) were early, and ultimately successful, experimenters in attempting to adapt the technology to their reconnaissance aircraft for artillery spotting purposes and general aerial reconnaissance. 

1915: If anything, the inter-communications situation grew worse in early 1915 as the tempo of war increased and enemy activity and the winter weather wrought damage to the existing military communication systems. Many telegraph lines and (as they expanded, telephone lines) were either strung out in the open on ad hoc supports or buried in shallow trenches. The passage of men and material wreaked serious damage on the system, as did the incessant shelling in certain sectors. At that time the high explosive shell fuses only exploded when the round had penetrated quite deeply into the ground and was thus, potentially, in close proximity to the buried telephone lines.

Increasing recourse was had to pigeons carrying coded messages from the Front Line to the battalion HQ and beyond. Originally the British Army on the Western Front did not have any messenger pigeons. But in September 1914, the French provided a nucleus aviary of 15 pigeons from which was developed a bird strength of thousands: 12,000 pigeons were deployed at the First Battle of the Somme in 1916, and by 1918, 20,000 birds were available for duty.

Wireless sets were installed in artillery spotting planes, but as the earlier sets weighed 70 pounds, or so, it usually meant the observer had to be left behind and the Royal Flying Corps (RFC) pilot operated the radio himself. Since the messages had to be in Morse Code this was quite skilful multitasking. Some pilots preferred to continue to use signal lamps.

Already concerns were rising about the Germans ability to intercept telegraph and telephone communication close to the Front Line. Experiments began to find intercept proof devices, including transmitters that used the ground as the conductor omitting the need for wires or cables.

1916: Stringent efforts were made by the RESS to improve the durability of the telegraph telephone/system and the standard of security. Where lines were above the ground out of the battle-zone, pole supports were improved and the lines/cables realigned away from areas where they might be damaged by passing traffic and the routine shelling by the Germans of favoured 'tender-points'. In the battle zone, telegraph/telephone cable were buried more deeply and routed so as to provide as much flexibility as possible to subsequent tactical movements across the battle zone.

One technical improvement was to create a readily adaptable telegraph/ telephone cable grid system that could be tapped into, or extended, frontally or laterally, with relative ease. Parallel and contiguous systems were established all along the Front Line. If certain sections were knocked out, then alternative routes could be exploited until the necessary repairs and reconnections had been made.

Meanwhile, the Germans enhanced their listening and cryptoanalysis work in a most determined way with ever more sophisticated equipment and methodology. British communication networks within three miles of the front Line were seriously compromised. Fortunately, in situ experiments with the Fullerphone - designed by Captain A.C. Fuller of the RESS - came to fruition and this interception-free Morse Code device using earth induction was adopted by almost all British units on the Western Front. Another system, the Power Buzzer and Amplifier (an earth induction telegraph) had also been widely adopted and used. But for security reasons it was largely superseded by the Fuller telephone version which was also adapted for use with the standard C Mark 1- III field telephones.

1917: Seriously disturbed by the Germans' success at listening and cryptoanalysis, the RESS also gave serious thought to deception tactics and had some success e.g. the plan for the Battle of Amiens.

Meanwhile, other more direct means of communication were more deeply explored.

The simplest amongst these were coloured flares (rockets, Very lights), klaxons, and lamps that could flash coded messages, of which the Lucas Lamp model proved to be by far the most practical. But in the latter case all depended on good visibility: with the increasing tactical use of smoke screens, signalling by lamp often became a problem.

Under the particularly dire operating conditions in the fighting on the Hindenburg Line, underground installations of the Buzzers continued to be operational when all other means were interrupted.

Some of the tanks employed in the Battle of Cambrai in 1917 had wirelesses installed. But they required large complicated aerials that in some cases had to be erected away from the tank.

Use of the wireless in the British trenches never really took off in the Great War because the radios were bulky and unreliable. They also required a reliable source of electricity - the lead/acid batteries were cumbersome - and the essential large aerial provided an excellent reference point for the enemy artillery. Further up the command chain at Divisional and Corps level, the wireless became increasingly used by the command structure, but even here the presence of the prominent aerial was problematic until the 'loop' aerial wireless set (W/T set) with its inconspicuous aerials became widely available.

Messenger dogs (Liaison dogs) were introduced for night work with mixed results. They tended to be spoiled as regimental pets and were much more susceptible to toxic gas and battle stress than the pigeons.

1918: It took the organisational chaos brought on by the German Spring Offensive to bring the artillery signallers into the RESS. However, an enormous amount of communications equipment was lost in the British Army's retreat and only shoe-string adaptations to a fortuitous, and undetected, duplication of the RESS's emergency cable system enabled a basic intercommunications network to continue to function fairly effectively. At the same time, on occasion, RESS troops joined their infantry colleagues in arms in repelling the Germans, gaining much respect for the Signals Section in the process.

Moreover, the technical lessons learned from these ad hoc adaptations to the system enabled the RESS to establish a lean and effective intercommunication system when the Allied advance really began in August 1918. It successfully supported the Army in the Allies' Final 100 Days Campaign against the German Army.


After rather disorganised start with a Signals Section that was not at all prepared for war on a large scale, and even less for the unforeseen vagaries of trench warfare, the RESS slowly organised itself and adopted new more appropriate methodologies. These changes brought about the necessary better intercommunication structures that help to dispel the disastrous 'Fog of War' syndrome and put the commander and the commanded into a closer working relationship.

The post-war evaluation of the lessons of the war included a more realistic appreciation of the role of the Signallers and their contribution on, and beyond, the battlefield. This ultimately led to the long delayed creation Corps of Signals in 1920 (shortly after conferred by royal approval as the Royal Corps of Signals) dedicated to British military communications around the Globe.

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