World War II: European Theater

American troops were fighting on foreign soil, surrounded by people speaking different languages, and operating in an environment exploited by Nazi spies, saboteurs, and collaborators. To counter these various threats, the Army relied on agents of the Army Counter Intelligence Corps. The CIC was quick to implement a control system with road blocks and roving patrols and to launch an aggressive security education campaign of posters and loudspeakers with the warning, “be wary of everyone in your area.” On the front lines, the CIC had great success in capturing espionage agents and, in the process, seized large numbers of clandestine radio transmitters, not unlike those in use by the Allies’ own behind-the-lines spies. They also uncovered numerous caches of enemy sabotage explosives. While successful counterintelligence operations protected Allied forces, the breaking of the cipher device called the “Enigma”, which was used by the German Army and Air Force for high-level communications, laid bare the enemies’ most secret plans.