After the loss of the Bismarck, Hitler was terrified of the public relations disaster of losing her sister ship, the KMS Tirpitz. Conversely, UK Prime Minister Winston Churchill was terrifed of losing track of the Tirpitz, only to have her show up in the middle of the Atlantic, where she would destroy the convoys supplying England and the build up for the Normandy invasion.
Both the Royal Air Force and the Roayl Navy dedicated large resources to destroying Tirpitz, including these experimental submarines, called X-Craft. X-51, a later version (1954) of the X-Craft can be seen just behind the wreck of the 1944 X-Craft in front. The X-7 carried two 3,750-pound slabs of explosives on either side of the keel. they were first deploed in Operation Source on Septemebr 15, 1943. The idea was that after navigating the fjord, the X-7 and her sisters X-5 and X-6 were targeted on Tirpitz, with three other X-Craft tartting the Cruiser Lutzow and the battlecruiser Scharnhorst. All X-craft were lost, but X-7 was able to deposit their explosives and damage Tirpitz enough to keep her immobilized for six months.
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