An account of the dramatic turning point in World War II that marked “the dawn of American might and the struggle for supremacy in Southeast Asia” (Times Higher Education). In far-flung locations around the globe, an unparalleled sequence of international events took place between December 1 and December 12, 1941. In this riveting book, historian Evan Mawdsley explores how the story unfolded . . . On Monday, December 1, 1941, the Japanese government made its final decision to attack Britain and America. In the following days, the Red Army launched a counterthrust in Moscow while the Japanese bombed Pearl Harbor and invaded Malaya. By December 12, Hitler had declared war on the United States, the collapse of British forces in Malaya had begun, and Hitler had secretly laid out his policy of genocide. Churchill was leaving London to meet Roosevelt as Anthony Eden arrived in Russia to discuss the postwar world with Stalin. Combined, these occurrences brought about a “new war,” as Churchill put it, with Japan and America deeply involved and Russia resurgent. This book, a truly international history, examines the momentous happenings of December 1941 from a variety of perspectives. It shows that their significance is clearly understood only when they are viewed together. “Marks the change from a continental war into a global war in an original and interesting way.”—The Sunday Telegraph Seven (Books of the Year) “Suspenseful . . . Mawdsley embarks on the action from the first day and never lets up in this crisp, chronological study . . . A rigorous, sharp survey of this decisive moment in the war.”—Kirkus Reviews

This is the story of the U.S. Navy's communications intelligence (COMINT) effort between 1924 and 1941. It races the building of a program, under the Director of Naval Communications (OP-20), which extracted both radio and traffic intelligence from foreign military, commercial, and diplomatic communications. It shows the development of a small but remarkable organization (OP-20-G) which, by 1937, could clearly see the military, political, and even the international implications of effective cryptography and successful cryptanalysis at a time when radio communications were passing from infancy to childhood and Navy war planning was restricted to tactical situations. It also illustrates an organization plagues from its inception by shortages in money, manpower, and equipment, total absence of a secure, dedicated communications system, little real support or tasking from higher command authorities, and major imbalances between collection and processing capabilities. It explains how, in 1941, as a result of these problems, compounded by the stresses and exigencies of the time, the effort misplaced its focus from Japanese Navy traffic to Japanese diplomatic messages. Had Navy cryptanalysts been ordered to concentrate on the Japanese naval messages rather than Japanese diplomatic traffic, the United States would have had a much clearer picture of the Japanese military buildup and, with the warning provided by these messages, might have avoided the disaster of Pearl Harbor.