The Lewis Gun (or Lewis Automatic Machine Gun) is a World War I era light machine gun of American design that was perfected and widely used by the British Empire. It was first used in combat in World War I, and continued in service with a number of armed forces through to the end of the Korean War. It is visually distinctive because of a wide tubular cooling shroud around the barrel and a top mounted drum-pan magazine. It was commonly used as an aircraft machine-gun, almost always with the cooling shroud removed, during both World Wars.