warfare The primary anti-submarine weapon was the convoy escort, typically a destroyer, armed with sonar (or Asdic) and depth charges. The capture of in July 1941 gave the British a much greater understanding of the capabilities of the German U-boats. In particular, the British were astonished by the maximum safe diving depth of the U-boats, which was far below the deepest setting on Allied depth charges. In the Pacific, the Japanese Navy failed to get a grip on the problems of convoy defence and failed to evolve effective anti-submarine tactics. With fewer escorts and many small convoys, the average number of escorts for a Japanese convoy was inevitably small and many were easily outmanoeuvred by the attacking submarines. Eclipse of the battleship The sinking of the British Prince of Wales and Repulse off Malaya on 10 December 1941 by Japanese aircraft marked the beginning of the end of the era of the battleship. By the end of the Pacific War, the tactical role of battleships and cruisers had been reduced to providing anti-aircraft fire to protect the vulnerable carriers and bombarding shore positions. The Japanese battleships Yamato and Musashi were both sunk by aircraft long before they could come within striking range of the American fleet. Dominance of the aircraft carrier The British attack on the Italian naval base at Taranto in November 1940, in which one Italian battleship were was sunk and two others heavily damaged, first demonstrated the full potential of the aircraft carrier. But the successful attack on ships in harbour did not convince advocates of the battleship that their day was over. It was the Japanese who really developed the tactical and strategic potential of aircraft carriers. Learning from their experiences in operations off the Chinese coast from 1937 onwards, the Japanese began to combine their carriers into permanent squadrons. While the British and Americans were still operating carriers on their own or sometimes in pairs, by 1941 the Japanese had organized a naval air fleet containing as many as six aircraft carriers. It was this force that struck the opening blow of the Pacific War at Pearl Harbor. The same carrier force then worked its way across the Pacific, attacking Allied forces at Rabaul, in the Netherlands East Indies, at Darwin and finally at Colombo and Trincomalee in Ceylon. The Allied forces in the East Indies were overwhelmed and the old battleships of the British