In 1941, the Reich Ministry of Air was shown the design for the Schmetterling surface to air missile. It rejected it, but recommissioned in 1943 as the Germany was subjected to heavy bombing. By 1945, they had a working prototype ready for mass-production. It was radio-controlled and had a warhead activated by a proximity fuse. If they had accepted the design in 1941, the Germans would have been able to use it to defend their air-space by 1943. This would have transformed the defence of the Reich, and prolonged the war by months if not years. How would the Allies have coped with such technology,?