A Priceless Advantage: U.S. Navy Communications Intelligence and the Battles of Coral Sea, Midway and the

Historians in Japan and the United States have already written much about the
period between 7 December 1941 and the Battle of Midway early in June 1942. a period when the United States was on the defensive in the Pacific and U.S. policymakers were unsure how the war against Japan should be prosecuted. Using their histories as background, this study focuses on an obscure but important program, the U.S. Navy's communications intelligence (COMINT) effort, which, despite its size and the trauma of Pearl Harbor, proved to be an unprecedented, sole, and timely source of information concerning Japanese intentions and strategy.

The study chronicles how, by reorganizing and redirecting its resources, U.S. Navy communications analysts engineered a spectacular triumph over Japanese naval cryptography and how the reports produced by these analysts contributed to development of a new U.S. naval strategy in the Pacific. By intercepting, deciphering, and translating the Japanese Navy's messages that contained their order of battle, the timetables for their military operations at Port Moresby, the Aleutians, and Midway, and a myriad of vital details concerning their most secret plans and intentions, the communications analysts were vindicated of any taint of failure from Pearl Harbor.