pioneered by Hungary during World War II by producing the 40M Nimrod based on the Luftvärnskanonvagn L-62 Anti II license acquired from Sweden. Germany followed later with their "Flakpanzer" series. German World War II SPAAGs include the Möbelwagen, Wirbelwind, Ostwind and Kugelblitz. Other forces followed with designs of their own, notably the American M16 created by mounting quadruple M2HB Browning machine guns on a M3 Half-track. The British developed their own SPAAGs throughout the war mounting multiple machine guns and light cannon on various tank and armoured car chassis and by 1943, the Crusader AA tanks, which mounted the Bofors 40 mm gun or two-three Oerlikon 20 mm cannon. Although used during the Normandy landings, by that point German aircraft were contained by the Allies own air forces and they were largely unneeded. Cold War and later The introduction of jet engines and the subsequent rough doubling of aircraft speeds greatly reduced the effectiveness of the SPAAG against attack aircraft. A typical SPAAG round might have a muzzle velocity on the order of and might take as long as two to three seconds to reach a target at its maximum range. An aircraft flying at is moving at a rate of about . This means the aircraft will have moved hundreds of meters during the flight time of the shells, greatly complicating the aiming problem to the point where close passes were essentially impossible to aim using manual gunsights. This speed also allowed the aircraft to rapidly fly out of range of the guns; even if the aircraft passes directly over the SPAAG, it would be within its firing radius for under 30 seconds. SPAAG development continued through the early 1950s with ever-larger guns, improving the range and allowing the engagement to take place at longer distances where the crossing angle was smaller and aiming was easier. Examples including the 40 mm U.S. M42 Duster and the 57 mm Soviet ZSU-57-2. However, both were essentially obsolete before they entered service, and found employment solely in the ground-support role. The M42 was introduced to the Vietnam War to counter an expected North Vietnamese air offensive, but when this failed to materialize it was used as an effective direct-fire weapon. The ZSU-57 found similar use in the Yugoslav Wars, where its high-angle fire was useful in the mountainous terrain. By the late 1950s, the US Army had given up on the SPAAG