The Flying Fortress was designed for a USAAC competition, announced in 1934, to find a modern replacement for the assorted Keystone biplane bombers, then in service. Since funding was lacking at the time, only thirty Flying Fortresses were fully operational when Hitler's forces invaded Poland in September 1939. The US was not involved in the fighting in Europe at the time, so it did not seem to be a matter of urgency. However, as it became clearer that US involvement was inevitable, after the Munich Crisis, orders for B-17s were increased.
The Pearl Harbor attack of December 7, 1941 finally brought the United States into the war and production of the B-17 rapidly increased. By July 1942, the US began forming the Eighth Air Force in Britain, equipped with B-17Es. The 'E' represented an important improvement over the earlier B-17s, in that it had a tail turret, eliminating a previous defensive blind spot. Production of the B-17F was undertaken by Douglas and Vega, a subsidiary of the Lockheed Aircraft Corp., but modifications were taking their toll in airspeed. There were more than four hundred modifications on the B-17F.
The B-17F lacked adequate defense against a head-on attack. By September 1943, the Flying Fortress showed its final shape during firepower tests on the XB-40, a modified B-17F with the advantage of a "chin" turret. The success of the chin turret, led to the delivery of the B-17G (the major production version), which was the first production variant to have a chin turret installed, under the nose. The Bendix turret held two .50-cal. guns, which increased the armament to thirteen guns. In all, there were 8,680 B-17Gs built by Boeing, Vega, and Douglas to make this the largest production variation. Produced in greater numbers than any other single model, more B-17Gs were lost, than any other model.
On 19 July 1943, US B-17s and B-24 Liberators carried out the first bombing raid on Rome. US bombing in Europe reached its high point in February 1945 with a 1,000-bomber raid on Berlin,
escorted by 400 fighters, and the Dresden raid (alongside RAF Lancasters) which, caused a massive fire storm to sweep the city. Meanwhile, B-17s were also helping to win the war against Japan, although by mid-1943 the larger Boeing B-29 had begun to take over the major strategic bombing missions in the Pacific theater.
The Boeing B-17, and the Consolidated B-24, were the United States' two standard heavy bombers until the introduction of the B-29 Superfortress. B-17s were flown by the United States Army Air Corps (USAAC), throughout the American participation in the Second World War. They were used by the US Eighth Air Force, based in the UK, to bombard German targets in Europe during daylight hours, a method which resulted initially in very heavy losses of aircraft and crew. As B-17 refinements progressed, along with better pilot training and tactics, it would become a formidable adversary in the Allied war against Germany.
B-17G-110-VE, N3193G, was delivered to the U. S. Army Air Corps as 44-85829, then transferred to the U. S. Coast Guard as PB-1G, BuNo 77255 in September 1946. It served at NAS Elizabeth City, North Carolina until May 1959. Ace Smelting Incorporated of Phoenix, Arizona bought it on May 11, 1959, gave it its current registration, then sold it to Fairchild Aerial Surveys of Los Angeles, California the same month. Aero Services Corporation of Philadelphia, Pennsylvania acquired it on August 2, 1965 and sold it to Beigert Brothers of Shickley, Nebraska on October 1, 1965. Aircraft Specialties Incorporated of Mesa, Arizona bought it on March 19, 1966 and flew it as tanker c34 and later tanker #34. It was flown to Hawaii in January 1969 to appear in the movie Tora Tora Tora. Globe Air Incorporated of Mesa, Arizona acquired it along with B-17G-85-DL, N9563Z on February 18, 1981. It is now named "Yankee Lady" and flies for the Yankee Air Museum at Yspilanti, Michigan.