Today one of the H12 flyingboats from Felixstowe was out escorting a convoy across the English Channel when it spotted a submarine in full buoyancy. The crew (Flight Lieutenant Warren Rawson Mackenzie, Flight Sub-Lieutenant Robert Frederick Lea Dickey, Air Mechanic J. Watts, and Air Mechanic E. E. Hughes) decided to attack immediately.
The pilot promptly dived on the submarine and dropped three 100lb bombs before the U-boat could dive. The submarine then disappeared under the water and oil and air bubbles appeared on the surface suggesting that the vessel had been damaged.
However at the time the destruction could not be confirmed, The Official history published in 1934 suggested that it was probably UB36 which was lost around this time. Later research suggests that UB36 was in fact sunk on 9 May 1917 after hitting a mine. There is no record of a submarine being lost on 28 June 1917, so we can only assume that whichever craft it was escaped.
Nevertheless, shortly after this Dickey was awarded the DSO for this action and the previous destruction of Zeppelin L43 on 14 June 1917.