The precursor to the V2, the German Vergeltungswaffe-eins was a pilotless aircraft or unguided missile launched from sites in northern France, Belgium and the Netherlands against south-east England. principally London. It was powered by a pulse jet engine, a primitive form of jet engine which was not used in manned aircraft because of its tremendous vibration when operating. It had a primitive guidance system which at best gave it an accuracy of a few miles.
Since it could not be accurately aimed, most V1s were pointed towards London. Because they were relatively slow (flying at sub-sonic speeds), they could be shot down by anti-aircraft fire or by fighter aircraft. Some RAF squadrons developed the skill of flying closely to a V1 at the same speed, then gently tipping the missile off course with a wingtip so that it would crash and detonate in open coountryside. Only a quarter of the missiles launched reached their target. Nevertheless, many V1s reached the capital, and the weapon is estimated to have caused 6,184 fatalities in and around London. After Allied advances captured launch sites in range of England, the Germans used V1s to bombard Antwerp, by then the main port of the Allied forces.