Fort Gillem is a United States Army military base located in Forest Park, Georgia, on the southeast edge of Atlanta in Clayton County. Founded in 1941, it was a satellite installation of nearby Fort McPherson. The base houses different supply and support units, including the U.S. Army Criminal Investigation Laboratory and the 3rd MP Group (CID), both units of the United States Army Criminal Investigation Command. It employs 456 active duty personnel, 1,663 Army reservist, and 1,667 civilians. In 1973, its 1,465 acres (5.93 km²) were annexed by Forest Park.