Wireless was the province of specialist communicators; even the battery signallers had nothing to do with such technology. Where wireless did have an impact on Percy and his fellow gunners was in the developing use of aeroplanes for observation.
Forward observation posts (O.P.s or O. Pips) were established well ahead of the gun positions so that officers could observe how well or how poorly the guns were doing in hitting their targets. Arthur Empey defined their function and their dangers succinctly:
“Observation Post. A position in the front line where an artillery officer observes the fire of our guns. He keeps on observing until a German shell observes him. After this there is generally a new officer and a new observation post.” (1)
Observers above ground had a much better view, of course, but the difficulty was how to communicate what they saw. It wasn’t so hard for observation balloons,* which were tethered in one spot behind the lines, and could communicate over telephone lines, but aeroplanes, which had greater mobility, also had greater challenges in communication.
A basic method of communication was to drop a flare over a target; then, with the aid of field glasses and trigonometry, ground spotters could calculate the location, assuming the plane was at the height it was supposed to maintain. Sending feedback on the accuracy of fire could be achieved by visual signaling, but there was a limited number of preset coded messages. More detailed reconnaissance information might have to be dropped in a weighted canister, or to be delivered in person after the plane landed.(3)
Wireless was the solution, even though the weight of the equipment meant that at first, only transmitters were taken aloft and communication was therefore only one-way. At least the pilot did not have to mount an aerial: a wire antenna trailed behind the aircraft. And though Morse code was not quick to spell out messages, pre-arranged codes could be sent to direct and correct artillery fire. (4)
* Observation balloons were also in Empey’s glossary: “A captive balloon behind the lines which observes the enemy. The enemy doesn’t mind being observed, so takes no notice of it. It gives someone a job hauling it down at night, so it has one good point.”
(1) Empey, Arthur Guy. Over the Top by an American Soldier who Went. 1918. 301-302.
(2) Varley, Frederick. “The Young Man’s Element, the Air.” Sketch. Beaverbrook Collection of War Art, Canadian War Museum. CWM 197110261-0777. The observer is also responsible for operating a Lewis gun.
(3) Talbot, Frederick A.A. “The Airman and Artillery.” Chapter 9 of his Aeroplanes and Dirigibles of War. 1915. np. Available from fullbooks.com
(4) Francis Penny of the Royal Flying Corps, quoted in Peter Hart. Bloody April: Slaughter in the Skies over Arras, 1917. 2012. np.