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
World War II by country end of World War II until 1955, when the country again became a fully independent republic under the condition that it remained neutral. The four occupations zones were French, American, British, and Soviet, with Vienna also divided among the four powers. This paralleled the situation in post-war Germany. See East African Campaign (World War II). The British overseas territory of Gibraltar has been a British fortress and bulwark for over 300 years. From the first days of World War II, the Rock became a pivot of the Mediterranean, Operation Torch, the invasion of North Africa, was coordinated from the Rock.