The Valiant (1962)
Having placed mines on the hull of a British warship whilst it is safe in harbour during the second World War , the two man crew of an Italian miniature submarine are captured and held prisoner whist the crew try and discover the nature of their mission!
Directed by: Roy Ward Baker
Starring: John Mills, Ettore Manni, Roberto Risso, Robert Shaw, Liam Redmond, Dinsdale Landen
Links: IMDb, Movie posters, Movie stills