When Japan attacked Pearl Harbor on December 7, 1941, and Germany and Italy joined Japan four days later in declaring war against the United States, intelligence essential for the Army Air Forces to conduce effective warfare in the European and Pacific theaters did not exist. The manuscript tells the intriguing story of how airmen build intelligence organizations to collect and process information about the enemy and to produce and disseminate intelligence to decision makers and warfighters in the bloody, horrific crucible of war. More that organizational history, this manuscript reveals the indispensable and necessary secret role intelligence plays in effectively waging war. It examines World War II as a watershed period for Air Force Intelligence and for the acquisition and use of signals intelligence, photo reconnaissance intelligence, human resources intelligence, and scientific and technical intelligence. Air Force History and Museums Program.