Includes bibliographical references (p. 275-282) and index.

MacArthur's codebreaking organization -- ULTRA's trials and errors, 1942 -- Breaking into the Japanese Army codes, January 1943-January 1944 -- ULTRA's great victory : the Hollandia Operation, January-April 1944 -- Misreading ULTRA, May-September 1944 -- The missing division : Leyte, 1944 -- The numbers game : Luzon, January-June 1945 -- ULTRA as seer : uncovering Japanese plans for homeland defense, June-August 1945 -- Conclusion -- FIGURES: A sample page from the Japanese Army Code Book -- A typical Japanese Army message enciphered for transmission -- The Mainline Radio Network, Imperial General Headquarters -- The Japanese Army message in Figure 1.2 transmitted in Morse Code -- Abbreviated Army Chain of Command -- PHOTOGRAPHS: Willoughby visits Akin's headquarters, Bataan, 1942 -- The first American cryptanalysts in front of the Henry Street headquarters of Central Bureau, 1943 -- B-25s attack a Japanese transport during the Battle of the Bismarck Sea, 1943 -- Blamey visits the codebreakers at Twenty-One Henry Street, 1943 -- Planning the leap to Hollandia, 1944 -- Members of Central Bureau's Hut 7, 1944 -- Listening to the enemy--radio intercept operators of the 126th Signal Radio Intelligence Company, mid-1944 -- The underground radio communications center of 86th Division Headquarters near Ariake Bay in southern Kyushu -- A representative of each of the services at Central Bureau, 1945 -- MAPS: The Pacific Areas -- Papua New Guinea operations -- Southwest Pacific Actions, January-October 1943 -- CARTWHEEL Operations, October 1943-February 1944 -- Anticipated and actual Allied landings, April 1944 -- Allied landings, New Guinea, April-May 1944 -- Leyte -- Luzon operations -- Disposition of Forces, Kyushu -- TABLES: Japanese units identified by SWPA in the Southwest Pacific, December 31, 1942 -- U.S. Army Intelligence estimate of Japanese forces in the Southwest Pacific, December 31, 1942 -- ULTRA-identified Japanese Air Units at Wewak, August 1943 -- Estimated and actual Japanese Ground Order of Battle...

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