The Project B tests were held in the Chesapeake Bay in July 1921. Airplanes of the First Brigade sank a captured German destroyer and then a an armored light cruiser. Next was the German battleship Ostfriesland, considered “unsinkable” due to its extensive compartmentalization. After a day of 230- and 600-pound bombs dropped by Marine, Navy, and Army aircraft, the battleship settled three feet by the stern with a five-degree list to port. Ostfriesland, it turned out, was not unsinkable from the air.