On May 1, 1917, a German seaplane loosed a torpedo and sank the British steamship "Gena" off Suffolk. A second German seaplane was downed by gunfire from the sinking "Gena". German torpedo bomber squadrons were subsequently assembled at Ostend and Zeebrugge for further action in the North Sea. Later in 1917, the U.S. Navy began to perform trials using a dummy torpedo that, in the first test, porpoised from the water back into the air and almost hit the aircraft that dropped it. Several British torpedo bombers were built, including the Sopwith Cuckoo, the Short Shirl and the Blackburn Blackburd, but a squadron was assembled so late in the war that it achieved no successes.