Destroyer Flotilla" (in reality, Captain Vian in ) and the , representing the fictitious which Bismarck destroys in the film. Their pennant numbers can be made out quite clearly, although they are reversed because of the film's convention that British ships should move from left to right on the screen and German ships vice versa. These were the last classes of destroyer built during the war, and the last to have the classic War Emergency Programme destroyers' outline. HMS Cavalier remained in service until 1972, the last RN destroyer to have served in the Second World War, and is now preserved at Chatham Dockyard to commemorate all these vessels, but the newer and larger HMS Hogue was broken up shortly after the film was completed, following a collision off Ceylon with the Indian cruiser (formerly ). The large models of the major warships Bismarck, HMS Hood, HMS Prince of Wales, HMS King George V, HMS Rodney and the s, are generally accurate, although HMS Hood is depicted in a slightly earlier configuration than that which actually blew up. The use of models in a studio tank was intercut with wartime footage and staged sequences using available full-size warships. Bismarck anti-aircraft guns, however, are represented by stock footage of British QF 2-pounder naval guns. Historical accuracySink the Bismarck! was made before 1975, when the British code-breaking at Bletchley Park was declassified, so it did not reveal that Shepard's hunches about the movements of the Bismarck were supported by intelligence. Direction finding and traffic analysis showed that on 25 May, Bismarck stopped talking to Wilhelmshaven and resumed with Paris, and Shepard committed to the belief that Bismarck was headed for the French coast. The radio switch from Wilhelmshaven to Paris might have been caused by Bismarcks position being closer to southern Greenland – northern Hebrides, which placed her under Group West instead of Group North. Nonetheless, Shepard's hunch was proved correct when, by good luck, a Luftwaffe Enigma transmission was intercepted and decoded at Bletchley Park, revealing that Bismarck was headed for Brest to repair an oil leak. The Luftwaffe's Enigma code had been broken early in the war, unlike the German naval Enigma code, which was only broken later and was subject only to traffic analysis during the Bismarck pursuit. Damage during its battle with HMS Hood and HMS Prince of Wales caused flooding that put Bismarcks bow barely above sea