During the Second World War, Allied concerns about German weapons development focused on the potential of a “super-weapon” on which the Germans could rely to turn the tide of war. German propaganda referred to the development of precisely such a weapon, and this made the British particularly fearful of its potential deployment in retaliation for their bombing of German cities. Although knowledge about the various German programs was vague, the Allies were aware of the long-range rocket projects underway in Germany. The “Vengeance” rockets (V1 and V2) were known to the Allies, as the following Air Scientific Intelligence report makes clear. The V1 “flying bomb” or “doodlebug” (so named for the sounds its engine made in flight), consisted of a fuselage containing electronics and the payload, a pair of wings, and a pulsejet engine for propulsion. Meanwhile, the V2 was a liquid-propelled rocket, the first long-range guided ballistic missile in the world. The V2s were based on the research of Wernher von Braun, whose work on liquid propulsion led to the launch of two test rockets by 1934. By war’s end, approximately 9,500 V1 and over 3,000 V2 rockets had been launched against Allied targets, predominantly English coastal cities. The Allies also feared the development of uranium bombs in Germany, and although these projects did exist, the Americans were the first to successfully produce such super weapons, the atomic bombs dropped on Japan in 1945.