At the end of World War II, the U.S. Navy began a design competition on 13 August 1945 for a carrier-based bomber which could carry a 10,000-pound (4,536 kg) bomb that was won by North American Aviation. Later that year, the Navy decided that it needed to be able to deliver atomic bombs and that the AJ Savage design would be adapted to accommodate the latest Mark 4 nuclear bomb, the next step in development from the more sophisticated imploding plutonium sphere design Fat Man Mk3 used on Nagasaki. A contract for three XAJ-1 prototypes and a static test airframe was awarded on 24 June 1946. The first prototype made its maiden flight two years later on 3 July 1948.^[1] That same year the US Navy began an interim capability program employing the Lockheed P-2 Neptune carrying a crash program reproduction of the smaller simpler all uranium ‘gun’ design Little Boy nuclear bomb as its first carrier launched nuclear bomber aircraft until the Savage was in service.