During the Second World War, General Dornberger was the military head of the army's rocket program, Zanssen became the commandant of the Peenemünde army rocket centre, and von Braun was the technical director of the ballistic missile program. They would lead the team that built the Aggregate-4 (A-4) rocket, which became the first vehicle to reach outer space during its test flight program in 1942 and 1943. By 1943, Germany began mass-producing the A-4 as the Vergeltungswaffe 2 ("Vengeance Weapon" 2, or more commonly, V2), a ballistic missile with a 320 kilometers (200 mi) range carrying a 1,130 kilograms (2,490 lb) warhead at 4,000 kilometers per hour (2,500 mph). Its supersonic speed meant there was no defense against it, and radar detection provided little warning. Germany used the weapon to bombard southern England and parts of Allied-liberated western Europe from 1944 until 1945. After the war, the V-2 became the basis of early American and Soviet rocket designs.