This book is part of the Army historical community's commemoration of the fiftieth anniversary of World War II. American victory in that conflict was brought about not only by the valor of our fighting men and the immensity of our productive capacity, but also by the availability of superb military intelligence. Much of this intelligence came from the ability of our armed forces to intercept and decipher the most secret communications of their adversaries. For many years security considerations prevented any public mention of these successes in the office histories. Now much of the story can be told. To preserve the memory of the Army's role in this intelligence war, a collection of documents on Army signals intelligence in World War II Signal II were published. This book is intended both for an Army audience and for the general public - including those World War II veterans who participated in the signals intelligence war and who for so many years were constrained to keep their contributions secret. The security barriers have now been lifted, and the Army is proud to acknowledge those contributions.

This book is part of the Army historical community's commemoration of the fiftieth anniversary of World War II. American victory in that conflict was brought about not only by the valor of our fighting men and the immensity of our productive capacity, but also by the availability of superb military intelligence. Much of this intelligence came from the ability of our armed forces to intercept and decipher the most secret communications of their adversaries. For many years security considerations prevented any public mention of these successes in the official histories. Now much of the story can be told. To preserve the memory of the Army's role in this intelligence war, the U. S. Army Center of Military History has joined with the History Office, U. S. Army Intelligence and Security Command (INSCOM), to publish this collection of documents on Army signals intelligence in World War II. INSCOM carries on the heritage of the Army's World War II Signal Security Agency, which by breaking the Japanese diplomatic ciphers and military codes helped speed the way of our forces to victory. The book is intended both for an Army audience and for the general public - including those World War II veterans who participated in the signals intelligence war and who for so many years were constrained to keep their contributions secret. The security barriers have now been lifted, and the Army is proud to acknowledge those contributions. Harold W. NelsonCharles F. Scanlon Brigadier General, US ArmyMajor General, US Army Chief of Military HistoryCommanding General, US Army Intelligence and Security Command

SIGNALS INTELLIGENCE, or SIGINT, is the interception and evaluation of coded enemy messages. From Enigma to Ultra, Purple to Lorenz, Room 40 to Bletchley, SIGINT has been instrumental in both victory and defeat during the First and Second World War.In the First World War, a vast network of signals rapidly expanded across the globe, spawning a new breed of spies and intelligence operatives to code, de-code and analyse thousands of messages. As a result, signallers and cryptographers in the Admiralty’s famous Room 40 paved the way for the code breakers of Bletchley Park in the Second World War. In the ensuing war years the world battled against a web of signals intelligence that gave birth to Enigma and Ultra, and saw agents from Britain, France, Germany, Russia, America and Japan race to outwit each other through infinitely complex codes. For the first time, Peter Matthews reveals the secret history of global signals intelligence during the world wars through original interviews with German interceptors, British code breakers, and US and Russian cryptographers."SIGINT is a fascinating account of what Allied investigators learned postwar about the Nazi equivalent of Bletchley Park. Turns out, 60,000 crptographers, analysts and linguists achieved considerable success in solving intercepted traffic, and even broke the Swiss Enigma! Based on recently declassifed NSA document, this is a great contribution to the literature." THE ST ERMIN'S HOTEL INTELLIGENCE BOOK OF THE YEAR AWARD 2014.

The importance of codebreaking and signals intelligence in the diplomacy and military operations of World War II is reflected in this study of the cryptanalysts, not only of the US and Britain, but all the Allies. The codebreaking war was a global conflict in which many countries were active. The contributions reveal that, for the Axis as well as the Allies, success in the signals war often depended upon close collaboration among alliance partners.

In 1974 Frederick W. Winterbotham's book The Ultra Secret disclosed the Allied success in breaking the German high command ciphers in World War II, and a new form of history began—the study of intelligence and its impact on military operations and international politics. This guide documents and annotates over 800 sources that have appeared in the past 20 years. It examines and evaluates primary and secondary sources dealing with the role of ULTRA and MAGIC in the Pearl Harbor attack, the battles of the Atlantic, Coral Sea, and Midway, and the campaigns in the Mediterranean, Northwest Europe, the Middle East, and the Pacific, as well as in the realm of espionage and special operations. It also covers sources on the Sigint and cryptanalytic programs of the Axis and neutral powers. The book examines and annotates primary and secondary sources on the role of ULTRA and MAGIC in the Pearl Harbor attack, the battles of the Atlantic, Coral Sea, and Midway, and the campaigns in the Mediterranean, Northwest Europe, the Middle East, and the Pacific, as well as in the realm of espionage and special operations. It also provides details on sources concerned with Sigint and cryptanalytic programs of the Axis and neutral powers.