Reissued 2017 with a new introduction Introduction to 2017 Edition The Center for Cryptologic History is pleased to reissue one of its earliest works, Fred Parker’s 1993 study, A Priceless Advantage: U.S. Navy Communications Intelligence and the Battles of Coral Sea, Midway, and the Aleutians , to commemorate the 75th anniversary of these important World War II battles. This is the second time that CCH has chosen to reprint it, the last being in 2011. While the layout and design of the previous edition were in need of a refresh, Mr. Parker’s research and writing stand the test of time. Few will argue with the seminal importance of the outcome of the Battle of Midway, not only on the war in the Pacific, but ultimately on America’s role in the world. After June 1942, Japan would never again be on the strategic offensive in the Pacific, even though three bloody years of fighting would ensue. After ultimate victory in World War II, the United States could no longer entertain notions of isolationism and was thrust into a leadership role which we have never yielded. The long-term repercussions of these relatively brief moments of history are undeniable. Table of Contents Introduction to 2017 Edition by John A. Tokar Historian’s Introduction to 2011 Edition by David A. Hatch Foreword to 1993 Edition by Henry F. Schorreck Introduction Part One: The Battle of the Coral Sea Japanese Strategy American Countermeasures Japanese Preparations for Moresby Naval COMINT Centers and Their Reports on Japanese Preparations for the Invasion of Port Moresby, Fiji, Samoa, and New Caledonia Melbourne Hawaii (Hypo) OP-20-G Washington/Negat Communications Intelligence and Japanese Intentions toward Port Moresby The Battle Begins Overview The Land Route to Port Moresby Notes Part Two: The Battles for Midway and the Aleutians Japanese Strategy Japanese Preparations COMINT Reflections of Japanese Preparations for Midway and the Aleutians The Battles Begin Conclusions Epilogue Notes Bibliography