Artillery officer issuing orders based on aerial observation, near Montauban, July 1916. This wireless set had an antenna about fifty feet long, the end of which can be seen snaking upwards along the right side of the photo. Due to weight limits, aircraft could only carry transmitters (not transmitters and receivers), and to see when the battery was ready to fire the aircraft had to circle back to see what ground panels had been laid out.

Source: IWM photo Q4036.