Submarine X 1

Submarine X1 is a 1968 DeLuxe Color British World War II war film loosely based on the Operation Source attack on the German battleship Tirpitz in 1943. In the film James Caan stars as Lt. Commander Richard Bolton, a Canadian, who must lead a group of midget submarines in an attack on a German battleship.

Commander Bolton is to train three 4man crews along the northern coast of Scotland for a trio of midget submarines equipped with side cargoes of explosives He must overcome tensions with some of his former crew members, while keeping their activities hidden from outsiders and German airplanes. The crews successfully fend off an attack by German parachute commandos, who discover their base. Bolton is forced to make hasty preparations for his attack before their submarine base can be destroyed.Two of the submarines are lost while attempting to cut through submarine nets at the entrance to the fiord. X2, is sunk by a German Eboats depth charges, and a second, the X1, is scuttled. One submarine crew is captured and taken to the German battleship for interrogation. X3, the surviving submarine penetrates the submarine nets in the fiord and places explosives under the German battleship. The submarine then manages to escape as the battleship explodes. ........

Source: Wikipedia