The Lewis machine-gun, usually called a "Lewis gun", was a weapon commonly installed on Canadian merchant ships.

First used during the First World War, the Lewis gun also saw widespread naval use during the Second World War. A flat drum on top of the weapon held ammunition (centre left), while an air-cooling jacket around its barrel created a distinctive profile (right). Fitted singly or in pairs on simple mountings, Lewis guns were used for anti-aircraft and general defence, but due to their limited range and effectiveness against aircraft they were gradually replaced by heavier weapons as the war progressed.

Machine-gun, Lewis Light, Model 1914
CWM 19620017-006