Known as “the Great War,” the world’s first truly global conflict is remarkable in what might now be termed modern espionage. World War I was witness to plenty of ”firsts.” Apart from the contribution made by aerial reconnaissance and the interception of wireless telegraphy, telephone and cable traffic, there was the scientific aspect, with new machines of war, such as the submarine, sea-mine, torpedo, airship, barbed wire, armored tank and mechanized cavalry in a military environment that included mustard gas, static trench warfare, the indiscriminate bombardment of civilian population centers and air-raids. Large-scale sabotage and propaganda, the manipulation of news and of radio broadcasts, and censorship, were all features of a new method of engaging in combat, and some ingenious techniques were developed to exploit the movement of motor and rail transport, and the transmission of wireless signals. The hitherto unknown disciplines of train-watching, bridge-watching, airborne reconnaissance and radio interception would become established as routine collection methods, and their impact on the conflict would prove to be profound. The Historical Dictionary of World War I Intelligence relates this history through a chronology, an introductory essay, an appendix, and an extensive bibliography. The dictionary section has over 400 hundred cross-referenced entries on intelligence organizations, the spies, and the major cases and events of World War I. This book is an excellent access point for students, researchers, and anyone wanting to know more about the world of intelligence in World War I.