On June 13, 1944, the citizens of London awoke to an eerie but puzzling buzz approaching the city. The morning stillness was shattered when the buzzing stopped and a strange aircraft plummeted from the sky, hitting a railway bridge and unleashing 1,800 pounds of explosive force. The bizarre aircraft was a German-made Vergeltungswaffen ("vengeance weapon") -- now known as the V1 Flying Bomb.
It was the first-ever use of a cruise missile in human warfare and the first of some 20,000 V1 bombs that would be launched at Allied targets between June 1944 and March 1945. The V1 wasn't an accurate weapon, but it didn't have to be; filled with nearly one ton of high explosives, the weapon was designed to sow fear into Allied civilians and undermine morale.