It was a run and gun battle 1,200 miles long high above Germany. Armed with the most sophisticated turrets ever devised, the air gunners from the United States Army Air Force and the Royal Air Force battled for their lives—and the key to Allied victory: strategic bombing.

The RAF and USAAF went into World War II confident that the bomber would always get through—but the determined opposition of the Luftwaffe challenged this military doctrine. Even with the most sophisticated turret defenses, bomber losses were heavy as the Allies clawed their way deeper into Europe.