The Fi 103 is also known as the V1 (Vergeltungswaffe 1, Retaliation Weapon 1), the first of the "secret weapons" that was expected to turn the war in favor of the Germans in 1944. Over 30,000 of these flying bombs with a warhead of 1,874 lb (850 kg) were produced until March 1945.

Hitting London for the first time on June 13, 1944, the projectiles were ground and air-launched. The RAF intercepted 1,771 V1's, the Hawker Tempest Mk.V scoring over one-third. Later the flying bombs were aimed also at other targets such as the ports of Antwerp in Belgium.

However, many thousands malfunctioned during or after launch, or were destroyed by the Allied forces therefore not reaching the intended targets. The V1 had the codenames Kirschkern (Cherry Stone) and Flakzielgerät (Flak Target Device) 76 (FZG 76). Flak was the abbreviation for Flugzeugabwehrkanon (anti-aircraft canon.)

A manned V1 was also intended, the Fi 103 R of which 175 were produced, however never reaching operational status.