Submarine X-1 is a 1968 British war film loosely based on the Operation Source attack on the German battleship Tirpitz in 1943.

In 1943, a Royal Canadian Navy Volunteer Reserve officer from Canada, Commander Bolton (James Caan) and a few surviving crew members of his 50-man submarine Gauntlet swim ashore after unsuccessfully attacking German battleship Lindendorf.

Bolton is assigned by Vice-Admiral Redmayne (Rupert Davies) to quickly train crews to man the submarines and sink the Lindendorf while it is hidden away in a Norwegian fjord.

Commander Bolton is to train three 4-man crews along the northern coast of Scotland for a trio of midget submarines equipped with side cargoes of explosives.

[2] The film was one of a series of war movies made by Walter Mirisch in Britain with an imported American star in the lead.