1921: Brig Gen William “Billy” Mitchell’s Martin MB-2 and Handley Page bombers sink several ships off the Virginia Capes. The tests study the use of bombs on ships to suggest how ship design could counter an air attack. The bombers sink a German sub, the destroyer G-102, the light cruiser Frankfurt, and the battleship Ostfriesland on 21 July to prove that unopposed aircraft could sink capital ships.