The Fieseler Fi103-A was a pilotless flying bomb powered by a pulse jet engine that was deployed by the Germans during World War Two.

The Fieseler Fi103-A was commonly referred to by the Germans as the V-1 (Vengeance weapon number 1). The Allies commonly called it the 'buzz' bomb or doodlebug due to the buzzing noise the pulse jet made. The V-1 was intended to be aimed in the direction of a target and when over the target the engine stopped, sending the V-1 and its lethal cargo of explosives in a steep dive to the ground, where it exploded.

Direction was maintained by a combination of a swinging pendulum, a gyroscopic compass and a simple rudder. Distance travelled was estimated by a countdown device driven by an airscrew at the front of the aircraft. The bomb was armed automatically after the aircraft had travelled 60 kilometers (38 miles)

The V-1 was launched either from a ground based ramp assisted by a catapult or from an aircraft such as the Heinkel 111.

The first flights of the prototype were made during late 1941 and early 1942 at the Peenemünde testing ground. Due to Allied counter measures the first operational use of the V-1 was not until July 1944, when one exploded next to a railway bridge on Grove Road, Mile End in London, killing eight people. Attacks continued until the end of the war.