not able to fight battles between fleets, and relied on commerce raiding instead. The extreme early success of Kriegsmarine U-boat wolfpacks led to the Allied development of an extensive and naval resource-straining convoy system. In addition to U-boats Germany also deployed the small numbers of surface warships she possessed, such as the "pocket battleships", her auxiliary cruisers, and a number of commercial vessels converted into merchant raiders, perhaps the most famous being . During World War II, elements of the United States Navy based in Brazil conducted operations in the Atlantic against German commerce raiders and blockade runners. In the Pacific, the U.S. Navy operated against Japanese merchant shipping, as well as engaging in offensive operations against ships of the Japanese Imperial Navy. The bulk of the Japanese merchant marine was sunk by American submarines. By the end of the war, only 12% of Japan's pre-war merchant tonnage was still afloat. The Indian Ocean raid was a naval sortie by the Carrier Striking Task Force of the Japanese Navy from 31 March to 10 April 1942 against Allied shipping and bases in the Indian Ocean. It was an early engagement of the Pacific campaign of World War II. The staff of the Imperial Japanese Navy decided to send some raiders to Indian Ocean waters during December 12, 1941 – July 12, 1942. The Germans had already been operating in the area and conducted mutual aid with Japanese submarines, in the form of re-supply and military intelligence. The Indian Ocean was the largest operating area involving direct contact between the two Axis partners, in which their primary objective was to keep pressure on the shipping lanes. The Japanese Navy participated in some commerce raiding, but concentrated its efforts toward a "decisive battle" in the Pacific, which never took place. See also Axis naval activity in Australian waters Demoralization (warfare) German auxiliary cruiser Atlantis Indian Ocean raid Japanese raiders in Indian Ocean Campaign Merchant raider Naval strategy Piracy Privateer Q-ship Tonnage war Unrestricted submarine warfare Notes References Lehmann, Ernst A.; Mingos, Howard. The Zeppelins: The Development of the Airship, with the Story of the Zepplin Air Raids in the World War. * Further reading Brown, David. Warship Losses Of World War II. 1995. . Blair, Clay, Jr. Silent Victory. Philadelphia: Lippincott, 1975. Mahan, Alfred, Captain. Influence of Seapower on History. Reeman, Douglas. The Last Raider. Arrow Books. . Novel detailing the last