The Navy and the Air Service were at cross purposes regarding the tests. Supported by General Pershing, the Navy set rules and conditions that enhanced the survivability of the targets, stating that the purpose of the tests was to determine how much damage ships could withstand. The ships had to be sunk in at least 100 fathoms of water (so as not to become navigational hazards), and the Navy chose an area off the mouth of the Chesapeake Bay rather than either of two possible closer areas, minimizing the effective time the Army's bombers would have in the target area. The planes were forbidden from using aerial torpedoes, would be permitted only two hits on the battleship using their heaviest bombs, and would have to stop between hits so that a damage assessment party could go aboard. Smaller ships could not be struck by bombs larger than 600 pounds, and also were subject to the same interruptions in attacks. Mitchell held to the Navy's restrictions for the tests of June 21, July 13 and 18, and successfully sank the ex-German destroyer "G-102" and the ex-German light cruiser in concert with Navy aircraft. On each of these demonstrations the ships were first attacked by SE-5 fighters strafing and bombing the decks of the ships with 25-pound anti-personnel bombs to simulate suppression of antiaircraft fire, followed by attacks from Martin NBS-1 (Martin MB-2) twin-engine bombers using high explosive demolition bombs. Mitchell observed the attacks from the controls of his DH-4 aircraft, nicknamed "The Osprey". On July 20, 1921, the Navy brought out the ex-German World War I battleship, . On the scheduled day, 230, 550, and bomb attacks by Navy, Marine Corps, and Army aircraft settled the "Ostfriesland" three feet by the stern with a five-degree list to port. She was taking on water. Further bombing was delayed a day, the Navy claiming due to rough seas that prevented their Board of Observers from going aboard, the Air Service countering that as the Army bombers approached, they were ordered not to attack. Mitchell's bombers were forced to circle for 47 minutes, as a result of which they dropped only half their bombs, and none of their large bombs. On the morning of July 21, in accordance with a strictly orchestrated schedule of attacks, five Martin NBS-1 bombers led by 1st Lt. Clayton Bissell dropped a single bomb each, scoring three direct hits. The Navy stopped further drops, although the Army bombers had nine bombs remaining, to assess damage.