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.