WWI Early Signalling & The Expeditionary Air Force

Working with input from Steve Stainthorpe and the research done for the Tactical Communications Wing Historical Training Facility, the following article is the second in the series which looks to discuss the history and development of RAF Communications.

From the outset, communications have proven to be an intrinsic part of military deployments. Ranging from pigeons, semaphore, heliograph or signalling lamps, the work carried out by Signal Units and early communicators has proven to be both decisive and game changing to a deployed force, with an engagement often lost or won on their access and availability. 

During World War I when wireless communications were very much in their infancy, flags, telephony, morse code or pigeons were used to provide vital communications between the air component, artillery and ground forces.

Although not extensive, the following section looks to cover the main forms of communications used in early deployments by the RFC and RAF.

Heliograph – The first known use of a heliograph was in 405 BC by the ancient Greeks. A heliograph is a signalling device in which sunlight is reflected from a moveable mirror. In Ancient Greece the absence of mirrors resulted in them using polished shields to reflect sunlight and send morse code. 

In WWI, heliographs would use a mirror to reflect sunlight and send morse code to give instantaneous communications over 50 miles. In 1915, a year after the first world war began, signalling discs were introduced. This meant that they could be operated undercover and far more discreetly.

Signal Lamps – Another very common piece of signalling apparatus that was used during WWI was signal lamps. These were particularly useful during the night but were also particularly good during periods of radio silence. However, in bright moonlight, rain or fog communication using signal lamps was difficult to see.

Flags – Poor visibility in the rain and the fog was also a downside to another type of signalling, flagging. With a maximum speed of 6 words per minute, it was certainly not the most effective form of communication. However, it was extremely portable and exceptionally quick to set up. This made it an extremely practical form of communication, especially in an advancing mission. The semaphore flag signalling system was conducted by waving a pair of handheld flags in certain patterns that represent different letters.

Telephony – At the beginning of WWI telephones were there to be used, however, they did not fend very well in the muddy, cold and wet conditions of the trenches. The noise of the battlefield also made it extremely difficult to understand voice transmissions through telephones. For this reason, the Army developed their telephones with a buzzer unit and morse key so that they could communicate even in noisy conditions without having to hear voice transmission.  

As signalling developed throughout the war, wireless communications began to also develop, and more successful forms of communication came into use.

Radio Communications – As the war went on, radio communications technology advanced and meant that it could start to play a much more important role. 

An early type of radio communication was known as a spark transmitter. This had two conducting electrodes that were separated by a small gap. When applied with sufficient voltage a spark would bridge the gap and form a mark or a dot that helped to send out morse code. While this was revolutionary technology in the trenches, it did have one main problem. This problem was that this particular form of communication weighed around 100lbs. 

Despite this, the British Army began using short wave radio tunes more often in the trenches. They then began to equip aircraft with voice radios in 1917. By the end of the first world war, the RAF had added radio to around 600 planes and had 1,000 ground stations.

90 Signals Unit Historical Training Facility

The information available at the Royal Air Force 90SU HTF and website goes deeper into detail on the history of RAF communications and their use. Tactical Communications Wing (TCW) is the expeditionary arm of 90SU and generates Force Elements @Readiness (FE@R) to enable Information Advantage for Air’s deployed operational commanders. Its deployable capabilities cover a scalable range of High Readiness Teams for a short duration, pulsed activity through to the larger and longer-term Air Deployed Operating Base enablers. Inherent within this is the ability to: establish deployed communications network infrastructures; enable Air’s operational information services and core command and control functions, and defend Air’s cyberspace to assure the digital backbone of Air operations. 

Here at cybersecurity-veterans.com, helping to support skilled veterans in a new career in cyber security is one of our main aims. The industry is rapidly growing and these veterans have extremely unique skill sets that could provide so much value to the industry as well as help them back into normal life. That is why we have sponsored the RAF 90SU historical training facility.

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