The use of Kite balloons with the fleet to detect submarines has been the subject of much debate with many suggesting that the balloon will give away the position of the ships. However the failure of the latest sortie by destoyers in the North Sea to score any hits has persuaded Admiral Beatty to give them a try.
A Kite Balloon Force of six destroyers, five of which carried balloons, was organized. The destroyers were to spread out across the known U-boat tracks and make an experiment in co-operative stalking. During the first operation, early in July, although submarines were sighted from the balloons, no attacks could be developed.
Yesterday however, a force of five destroyers (three with balloons) went out again, and this morning the observer in the balloon flown from the Patriot (Flight Lieutenant Osborne Arthur Butcher) sighted a U-boat on the surface twenty-eight miles away,
The destroyer raced away to the area. Before she arrived, the submarine had gone under, but shortly reappeared on the surface four miles off. The Patriot opened fire, but the U-boat went under again before a hit could be made. The destroyer, guided by the observer in the balloon, then dropped depth-charges. A small quantity of oil came to the surface, insufficient to indicate certain damage to the submarine, and the ships kept a close watch over the area. A little later there was an under-water explosion in the place where the U-boat had submerged, and a great oil patch began to form. It is possible that this was the U69 which was lost around this time with all 40 crew. However German sources are unable to corroborate this loss. And some sources suggest the boat was still operating until 24 July 1917.
This success led to the opening of new balloon bases at ports where destroyers and other patrol vessels were favourably placed for submarine hunting.