A superb wartime adventure, the Silent Enemy is the true story of Lieutenant Crabbe, a Royal Navy bomb and mine disposal officer sent to Gibraltar on a urgent mission to undo damage being inflicted on the fleet by sly Italian frogmen led by a brilliant underwater engineer. Though he has never dived before Crabbe takes to the underwater world like a fish, and with the help of a plucky NCO and dedicated but tiny band of men turns back the hidden menace. Crabbe and his courageous crew ultimately stop the Italian 10th Flotilla divers from turning the tide of the war.
Characters and acting are sharp. Cinematography and staging on land and especially underwater are very good. Writing is great too. The military historical significance is that these underwater demolition techniques and technologies are the precursors of modern Navy SEALs, Special Boat Squads, etc. The movie significance is that the characters and plot elements foreshadow every James Bond and action movie that's ever had frogmen, underwater fight scenes, secret ships, mini-subs, or stealty sub-surface saboteurs. Being drawn from real life, I found The Silent Enemy even more compelling.