As a lightweight machine gun, the American designed Lewis Gun made a place for itself in World War I & World War II.

Although machine guns were widely issued and used during the bloody opening months of World War I, these deadly weapons proved to be too heavy to be tactically mobile. Casting around for existing designs to supplement inadequate stocks of the excellent Vickers gun, the British adopted the US-designed Lewis gun, which had not found favour with the US Army. The British quickly came to realise that while the new weapon was unable to match its heavier cousin in terms of robustness and sustained firepower, its light weight and the fact that it could be fired both prone and on the move made it an ideal weapon both to support advances and defend captured trenches. Serving on the Western Front and across the world, the Lewis gun soon became the core of the British and Dominion infantry section, and was widely adopted by the Germans too; even so, the US Marine Corps found on landing in France that their Lewis guns were replaced by an inferior French weapon, the CSRG 'Chauchat'.

Although offering significant advantages over its rivals, such as the Danish Madsen, American BAR and German MG 08/15, the Lewis was not without its faults. Although the distinctive cooling tube proved to be a very effective flash hider and the weapon's 'forced cooling' system and open-bolt design helped to limit overheating, like all fixed-barrel guns it couldn't offer true sustained fire. Its magazine feed system made it easier to carry than rival models employing non-disintegrating fabric belts, which trailed everywhere, picked up water and froze, but the Lewis's open-bottom pan magazine let dirt into the mechanism, and the pans were relatively flimsy. Even so, it won a lasting reputation and became an iconic weapon of World War I.

Adopted by an array of countries from the Netherlands to Japan during and after World War I, 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, being the first weapon to be used to shoot down an enemy aircraft from an aeroplane - indeed, it was the most important aircraft-mounted machine gun in virtually every air force well into the 1930s. Although it was superseded by the Bren in British service in 1937, the outbreak of World War II meant that thousands returned to active service to counter weapons shortages, and it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. Fully illustrated and written by an authority on this iconic weapon, 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.