The V-2 (German: Vergeltungswaffe 2, "Retribution Weapon 2"), with the technical name Aggregat 4 (A4), was the world's first long-range guided ballistic missile. The missile, powered by a liquid-propellant rocket engine, was developed during the Second World War in Germany as a "vengeance weapon", assigned to attack Allied cities as retaliation for the Allied bombings against German cities. The V-2 rocket also became the first artificial object to travel into space by crossing the Kármán line with the vertical launch of MW 18014 on 20 June 1944.