Pretty, isn't it

Majestic looking now, this silhouette once sparked terror in Axis industrial and military installations. They would come in waves, hundreds of planes at a time, "turning the sky black with bombers," as the saying went. Early in its career, the B-17 had to fend for itself against the Luftwaffe's fighter pilots, but by mid-war long-range allied fighters such as the North American P-51 Mustang would fly cover and keep the fighters busy. But nothing could distract the flak -- essentially fragmentation grenades that exploded near the bombers.