The Silent Enemy is a black and white 1958 British action film, directed by William Fairchild and starring Laurence Harvey, Dawn Addams, Michael Craig and John Clements. Based on Marshall Pugh's 1956 book Commander Crabb, the film follows the publicity created by Lionel Crabb's mysterious disappearance and likely death during a Cold War incident two years earlier (April 1956).The film depicts events in Gibraltar harbour during the World War II Italian frogman and manned torpedo attacks, although the film's depiction of the events is highly fictionalised. It was the first Universal Pictures film in SuperScope.

Plot

During the 1941 Italian manned torpedo raid on Alexandria, two British battleships, and , are severely damaged. The British are worried that this new tactic will afford the Italians naval supremacy in the Mediterranean and the ability to strike their primary target, the Royal Navy base at Gibraltar.