The aim of the attack, which involved almost 600 planes, was to disrupt German plans to develop a long-distance rocket, the V-2.
After the failure of the Luftwaffe’s 1942 bombing campaign against British cities, the so-called Baedeker Raids, the Germans were planning to strike back with their ‘V-weapons.’
The first of these, the V-1 ‘flying bombs’ (sometimes called ‘buzz bombs’ or ‘doodlebugs’) were pilotless rocket-propelled planes that were designed to be launched from ramps. The V-1s did not become operational until June 1944, after D-Day. Although they flew straight and level, they were difficult to stop because of their high speed. They could sometimes be brought down by barrage balloon cables or shot down by anti-aircraft guns or intercepted by specially modified Spitfires.The V-2s were first launched against London in September 1944. They could not be intercepted. They were liquid-oxygen powered rockets which, once underway, would arrive at their destination. They travelled faster than sound. Hence there would be no sirens, no warning.