Boeing YB-40 Flying Fortress Boeing YB-40 Flying Fortress The Boeing YB-40 Flying Fortress was a modification for operational testing purposes of the B-17 Flying Fortress bomber aircraft, converted to act as a heavily armed gunship for other bombers during World War II. At the time of its development, long-range fighter aircraft such as the North American P-51 Mustang were just entering quantity production, and thus were not yet available to accompany bombers all the way from England to Germany and back. Work on the prototype, Project V-139, began in September 1942 by converting the second production B-17F-1-BO (serial number 41-24341) built. Conversion work was
Military history of the United States during World War II Empire and Chinese forces in Burma and suffered many casualties. On 10 August 1944 the Marauders were consolidated into the 475th Infantry. The U.S. also had an adviser to Chiang Kai-shek and Joseph Stillwell. Units of the Tenth Air Force, Fourteenth Air Force, and Twentieth Air Force of the USAAF also served in the theatre, including the previously mentioned "Flying Tigers". Military history of the United States during World War II The military history of the United States in World War II covers the war against Germany, Italy, and Japan, starting with the 7 December 1941 attack on Pearl Harbor.