Your great uncle was in good company. JRR Tolkien was Signals Officer in the Lancashire Fusilers. Many of the terms he would used have since passed into the English Language, Toc H , Wilco and even Roger are all Telegrapheses.
Signallers were trained in Morse, Flags, Telephone techniques, pigions and flares. They were also responsible for keeping lines intact, when every shell or boot could cut them. He must have been one hell of a man.