The Boeing B-29 first flew on 21st September 1942. By the time, orders for 1500 aircraft had been placed the B-29 programme having been given maximum priority following the Japanese attack on Pearl Harbor. The first YB-29 evaluation aircraft were delivered to the 58th Bombardment Wing in July 1943, B-29-BW production aircraft following three month later. The other main versions of the B-29 that made their appearance during the war were the B-29A-BN with four-gun forward upper turrets and increased wingspan, and the B-29B-BA with a reduced gun armament but increased bomb load.The B-29 had many technical innovations such as remotely controlled gun turrets. At the end of 1943, the decision was taken to use the B-29 exclusively in the Pacific theatre. The B29 was sent to the 58th and the 73rd Bombardment Wings based in India and South-West China in the spring of 1944. The first combat mission was flown on the 5th June against Bangkok in Japanese-held Thailand before attacks on the Japanese main land were initiated ten days later. The B-29s that dropped the atomic bombs on Hiroshima and Nagasaki on the 6th and 9th August 1945, Enola Gay and Bocks Car belonged to the 509th Bombardment Wing, which was to become the US principal nuclear weapons trial unit. The B-29 continued to be mainstay of the USAF strategic Air Command for several years after 1945, and saw almost continual action during the Korean War.
