The Silent Enemy is based on Commander Crabb, a book by Marshall Pugh. This is the true story of young Lieutenant Crabb (Laurence Harvey), who in 1941 arrives in Gilbaltar to learn the rudiments of deep-sea diving. Crabb isn't interested in recreation, however; there's a war on, and it is common knowledge that a band of Italian frogmen have been sabotaging the British naval forces. Without official permission, Crabb and a band of hardy volunteers take on the task of scuttling the enemy's guerilla activities. Silent Enemy is at its best during its underwater sequences, in which both British and Italian frogmen deploy an astonishing variety of deep-sea weaponry.

The Silent Enemy is a 1958 action film directed by William Fairchild. It stars Laurence Harvey as Lionel "Buster" Crabb and describes his exploits during World War II. Based on Marshall Pugh's book Commander Crabb, it was made following the publicity created by Crabb's mysterious disappearance and likely death during a Cold War incident a year earlier.

The film depicts events in Gibraltar harbour during the World War II Italian frogman and manned torpedo attacks, although the film's depiction of those events is highly fictionalised.

Release Date: October 2, 1959