The following is the audio track for the 1945 propaganda film released by the US Army Air Forces discussing the development of Boeing B-29 bomber, an American four-engined propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. The B-29 was designed for high-altitude strategic bombing, but also excelled in low-altitude night incendiary bombing and in dropping naval mines to blockade Japan. B-29s dropped the atomic bombs on Hiroshima and Nagasaki, the only aircraft ever to drop nuclear weapons in combat.