On June 6, 1944, the Allies launched Operation Overlord, the largest, most hazardous amphibious assault in history. The objective: establishment of a lodgment area in Normandy from which the Allies could strike at the heart of Germany and destroy the German armed forces. Air supremacy over northwest Europe was an absolute prerequisite for the success of the invasion, and to achieve it the U.S. Army Air Forces launched two campaigns aimed at destroying...