July 21----The battleship Ostfriesland was sunk by heavy bombs dropped by Army bombers in the last of a series of tests to determine the effectiveness of air weapons against combatant ships, and the means by which ship design and construction might counter their destructive capability. The tests, in which the Army participated at the invitation of the Navy, were carried out off the Virginia capes beginning 21 June. On that day, the German submarine U-117 was sunk by 12 bombs dropped from Navy F5L's at 1,100 feet.

On the 29th, Navy aircraft located the radio-controlled U.S. battleship ex-Iowa (Battleship No. 4) in 1 hour and 57 minutes after being alerted of her approach somewhere within a 25,000 square mile area and attacked with dummy bombs. On 13 July, Army bombers sank the German destroyer G-102, and on the 18th the light cruiser Frankfurt went down under the combined effect of 74 bombs delivered by Army and Navy aircraft. Tests against the Ostfriesland began on 20 July when Army, Navy and Marine Corps planes dropped 52 bombs, and they ended the next day when the Army delivered eleven 1,000- and 2,000-pounders. The Navy had originally planned the tests to provide detailed technical and tactical data on the effectiveness of aerial bombing against ships and the value of compartmentation in enabling ships to survive bomb damage.