Shortly after the Allied landings in France the Germans unleashed the first of their so-called 'revenge weapons' against London, the V1 flying bomb. Launched from specially constructed sites in northern France, the fast, small, pulse-jet powered and pilotless aircraft were aimed at London with the intent of destroying civilian morale in order to force the British government to negotiate a peace. This dangerous new threat drew an immediate response, and the Air Defence of Great Britain (as Fighter Command had been temporarily renamed) established layers of defence that included a gun line and balloon barrage.