Camp Forrest, located in a wooded area east of the city of Tullahoma, Tennessee, was one of the U.S. Army's largest training bases during World War II. An active army post between 1941 and 1946, it was named after Civil War cavalry Confederate General Nathan Bedford Forrest.

Built in 1926 by the Tennessee National Guard, the 1,040 acres (420 ha) facility was named Camp Peay after then-Tennessee Governor Austin Peay.

In 1940, the U.S. Army took over Camp Peay and expanded it to 85,000 acres (34,000 ha) just beyond the camp's old boundaries. In 1941, the camp was renamed at the direction of Army Chief of Staff General George C. Marshall, because "it was not Army practice to name an installation used by federal troops after a local politician who did not have a distinguished military background," the Center of Military History would write.

Because the Army had leased Peay, he instructed the National Guard Bureau to contact the Tennessee state authorities for their recommendations on a new name. Furthermore, he directed that “the desires of the State authorities will be followed unless it is found that the name selected is unsuitable for psychological or other reasons.” The Tennessee adjutant general recommended Nathan Bedford Forrest, a native Tennessean whose birthplace was nearby. Despite the notorious reputation of Forrest, a prewar slave trader and then a founder of the Ku Klux Klan after the Civil War, the Historical Section and the G–3 accepted this recommendation. In January 1941, Deputy Chief of Staff Maj. Gen. William L. Bryden approved the name change. The Chicago Defender, an African American newspaper, took great umbrage at the name, and the Illinois legislature attempted (without success) to get the name changed when the state’s National Guard division reported there for training.

Camp Forrest was a training area for infantry, artillery, engineer, signal organizations, and cooks. It also served as a hospital center and temporary encampment area for troops during maneuvers. Major General George Patton brought his 2nd Armored Division from Fort Benning, Georgia, for maneuvers.

William Northern Field, an air training base, was an addition used by the Army Air Forces to train crews of four-engined B-24 bombers.

Incoming troops had amenities typical of military installations of the era: service clubs, guest houses, a library, post exchanges, a post office, hospital facilities, a chapel, theater, and barracks buildings. The camp was also home to Red Cross and Army Emergency Relief facilities. Recreation facilities included swimming, archery, tennis, a sports arena, and a nine-hole golf course.

Camp Forrest officially became a prisoner-of-war camp on May 12, 1942. The camp housed Italian and German POWs. Prisoners became laborers at Camp Forrest in the hospitals and on farms in the local community. The camp also held Japanese, German, and Italian-American civilians who were arrested at the outbreak of the war under a program called "Alien Enemy Control". Many of these internees were incarcerated without legal process. Official government documents made available in the late 1990s indicate that over 25,000 "alien enemies" were held at various locations throughout the United States. Camp Forrest's population was over 700, of whom about 200 were of Japanese ancestry. German internees at Camp Forrest published a newsletter titled The Latrine. In 1943, Camp Forrest internees were transferred to other internment camps to make room for actual POWs captured on the field of battle.