Review of 'Adapting to the Mobile Battlefield, Communications in the BEF during the Last 100 days' by Andy Powell (November 2016)

‘Communications’ is not a very glamourous topic and is often overlooked by historians when covering the First World War. But we must not forget that communication is essential for command and control of the battlefield.

SS 148 and 191 from 1917 covered intercommunication in the field. This covered cables, runners, pigeons as well as telephones. Telephones were the only type of  ‘real-time’ communication but were fragile to artillery shells and not secure when used within approximately one mile of the front.

General Maxse wanted all telephones disabled once action started. Buried cables became obsolete once the war became mobile. Hanging cables above the ground became very sensitive to a variety of problems including shortages of material. Despatch riders continued to be used after the war became more mobile as messages were carried to brigade HQs but runners were usually required carrying messages to division HQs.

With much more transport on the few available roads, clogged roads and unexpected movement of HQs resulted in messages going astray or arriving very late. Pigeons were more effective when the HQs were static but their effectiveness decreased once the war became mobile. At this point we should not forget the visual forms of communication – flags, discs, rockets, panels and lamps. Signal codes were agreed on before any action and colour sequence would be determined within each Corps. The use of signal lamps was limited to front lines communicating with the rear but these were reduced in efficiency by smoke or fog.

Wireless telegraphy (WT) was the only form of communication which could be used under all weather conditions. It used Morse Code, usually at the rate of 8 words a minute, but required a cypher if secrecy was to be maintained. In fact, ‘messages in clear’ became more common during the last 100 days. The BEF were late in coming to the universal use of WT, the German Army went to war in 1914 with all its units using WT, their machines were made by AEG Telefunken and by Siemens.

Amongst the units in the BEF, the Canadian Corps used WT more widely and earlier than either the British or the Australians. Once the war became mobile after the battle of Amiens (August 1918), WT was essential for a mobile army. Initially WT was seen as insecure and the range was limited. The early sets were heavy and not seen as portable. In contrast to the army, the Royal Navy embraced the technology of wireless telegraphy and all ships were equipped with sets and aerials using a network of shore stations in order to communicate with ships in the North Sea, the Channel and the Atlantic. The RFC also embraced wireless telegraphy and by 1916 aircraft were fitted with a light weight receiver and a Marconi half-kilowatt ground transmitter. In operation a 150ft aerial had to be unreeled and the signal distance was estimated at 10 miles.

At the outbreak of the war in 1914, the equipment for WT which was available for use in the field consisted of a wagon mounted 1.5kW spark set which required four horses. Eventually the wagon was replaced by a lorry. The set required a 70ft mast and had a range of about 100 miles. It was manifestly unsuitable for the conditions of both trench and mobile warfare. Trench sets became available in mid-1916, these used valves and were ‘spark sets’, with a power of 50 watts they were technically portable but required extra manpower to carry the spare accumulators. They required a 12 foot aerial and often attracted unwanted enemy attention and its range initially was no more than 4000 yards.

Improvements soon arrived, the Wilson 130 W spark transmitter was used at Corps HQ with a 30 foot aerial and the ability to communicate with trench sets at a distance of between four and ten miles. The earliest radios to be used in the trenches were the W/T Trench Set 50 watt which was used for communication from Brigade to Division. A vulnerable feature of these was the need to have an aerial of length ranging from 60 to 80 yards mounted on masts, making them easy targets for enemy gunfire.

The next development was associated with valves. An entirely new type of valve was developed by the French. Known as the TM or the R-valve it was ‘hard’, being evacuated to low pressure with glass and metal components welded together. In 1917 the army was issued with the new W/T spark 20 watt Set also known as the ‘Loop Set’, it required two valves, a 6-volt accumulator and a 32-volt HT battery. Approximately 4000 of these transmitters and receivers were made.

The first problem experienced at the front-line use of these transmitters was ‘jamming’. Too many sets using the same wavelength for transmission resulted in failure to receive messages. The answer was simple, Corps would allocate separate wavelengths in order to divisions and they would allocate in turn.
In the all arms battle, aircraft, artillery and tanks had to co-operate especially over counter-battery fire. This was made more efficient by the use of WT. An aircraft had approximately half to hour to indicate the presence of enemy guns otherwise replacement craft had to be sent up. Communication between tanks and infantry remained pretty simple – flags or a helmet held on a rifle in front of the tank where it could be seen.

As in all things, real time communication was very difficult. Reaching for the telephone was not the usual answer. If WT was to be used, encryption of the message was essential. The French were particularly good at encryption and were able to break the German codes on a regular basis.

During the last 100 days, deception was extended into radio transmission. Knowing that the German intelligence was listening in to all Army and Corps radio traffic, planning for an attack would include random silent days. The call signs were changed on a daily basis and the impression that key troops (e.g. the Canadian Corps) were being moved to false fronts became common practise.  The traffic analysis of German communications would identify the position of their HQs for all German units. Knowing this British radio transmissions would be a mixture of key information along with extensive radio traffic between units not linked to the command and control centre.
WT was the rising star but shortage of sets, aerials and the problems with ‘jamming’ had to be solved. In 1920, the Royal Corps of Signals was created by Royal Warrant, signed by the Secretary of State for War, Winston Churchill.

Report by Peter Palmer