In the summer of 1935, Boeing unveiled the Model 299—later christened the B-17 Flying Fortress—and changed the face of aerial warfare forever. Though initially dismissed as an expensive luxury, the four-engine heavy bomber proved its worth over every combat zone of World War II, most notably in the skies over Europe. Flying alongside the B-24 Liberator, the Fortress formed the backbone of the USAAF strategic bombing campaign, crippling German war industry one formation at a time. With up to thirteen .50-caliber machine guns bristling from its frame and a legendary ability to absorb punishment, the B-17 became more than a machine; it became a symbol of American resolve. The Memphis Belle completed her combat tour in 1943 and returned home a national hero.