The gatecrashers - Alexander Fullerton

The last of the 9-volume Nicholas Everard series is based on a true incident, Operation Source, when six midget submarines (X-craft) were towed underwater from Scotland to northern Norway by larger submarines and released there to attack Tirpitz, Scharnhost and Lutzow in Altenfjord.

Pitching the X-craft against Tirpitz seems like matching tadpoles against a whale - except that the whale has an unprotected underbelly and the tadpoles two-ton explosive charges like blisters on their sides. If they can survive the nightmarish 2,000-mile submerged tow, Paul Everard commanding X12 will have a chance to gatecrash the fjords and cripple the ship which Churchill referred to as 'the Beast'. Whether or not he succeeds the chances of getting out alive are slim. If he fails, Nick Everard commanding the escort of Arctic convoy PQ19 is in for bad trouble - none of his ships can stand up to the weight of Tirpitz's broadsides. As The Gatecrashers draws to its thunderous climax, father and son face their final and most searching test...