Catoctin Mountain Park provides the landscape where the Mountain Spies story begins. During World War II, the rugged terrain and isolation of the Catoctin Mountains made the area ideal for secret training and experimentation. In 1942, the Office of Strategic Services (OSS), the precursor to the CIA, established a covert paramilitary training site at nearby Camp Greentop known as Camp B-2. Here, small teams trained in sabotage, guerrilla warfare, clandestine communications, and resistance coordination before deploying to occupied Europe. The same protected mountain landscape also hosted the presidential retreat originally called Shangri-La, later renamed Camp David by Dwight D. Eisenhower. The proximity of OSS training, military intelligence activity at Fort Ritchie, and presidential leadership in the Catoctins illustrates how this quiet Appalachian corridor became an important setting for the development of American intelligence and national security during and after World War II.

Fort Ritchie, located in the Catoctin–South Mountain corridor, served as the U.S. Army’s Military Intelligence Training Center during World War II. Here, thousands of intelligence specialists known as the Ritchie Boys were trained in interrogation, psychological warfare, and battlefield intelligence. Many were European refugees whose language and cultural knowledge proved invaluable during the Allied advance across Europe. Fort Ritchie operated within a broader regional intelligence system that included POW screening at Pine Grove Furnace POW Camp and strategic interrogation operations at PO Box 1142 at Fort Hunt. During the Cold War, the region’s strategic role expanded with the construction of the underground command center at Raven Rock Mountain Complex, which serves as the Alternate National Military Command Center supporting continuity-of-government and national command communications.

Pen Mar Park sits along the crest of South Mountain on the Pennsylvania–Maryland border and offers sweeping views across the Cumberland Valley. Developed in the late 19th century as a railroad resort destination, it became a popular scenic overlook and gathering place for visitors traveling the mountain line. In the Mountain Spies narrative, Pen Mar represents the high ground of the Catoctin–South Mountain corridor—terrain that later supported military training, intelligence activities, and strategic infrastructure throughout World War II and the Cold War.