On this day 20 May 1917
On this day 20 May 1917 First submarine attacked by flying boat
On May 20 1917, a Curtiss Large America H-12 is the first seaplane to attack a U-boat, the UC-36. It was probably damaged in the attack because it was rammed off Ushant (4842N 0514W) the following day by French steamer Molière. 27 dead (all hands lost).
The RNAS operated 71 H.12s from April 1917. Lieutenant Commander John Cyril Porte at the Seaplane Experimental Station, Felixstowe designed a modified version of the H.12 which was called the Felixstowe F.2, variants of which were built and used in antisubmarine patrols until the end of the war.