During World War I, the British adopted the US-designed Lewis gun as an infantry weapon, realizing that its light weight and the fact that it could be fired both prone and on the move made it ideal for supporting advances and defending captured trenches. Later adopted by an array of countries from the Netherlands to Japan, the Lewis successfully served as the primary or secondary armament in armoured fighting vehicles and in both ground-based anti-aircraft and aircraft-mounted roles. Although it was superseded by the Bren in British service in 1937, the outbreak of World War II meant that thousands returned to active service, and it played a key role as far afield as Libya, with the Long-Range Desert Group, and the Philippines, with the US Marine Corps. Written by an authority on this iconic light machine gun, this is the fascinating story of the innovative and influential Lewis gun, from the trenches of World War I to the Libyan desert and Pacific islands of World War II and beyond.