The B-17 or Flying Fortress was the most important American bomber of World War II. This profile of the aeroplane contains images of the bomber in action, including the 20 airworthy Fortresses that regularly appear at airshows in the US and Europe. In all 12,731 B-17s were built between June 1939 and April 1945. The 50th anniversary of the 8th Air Force's daylight raids on Germany is celebrated in 1993.