Camp Shelby is a military post whose South Gate is located at the southern boundary of Hattiesburg, Mississippi, on U.S. Highway 49. It is the largest state-owned training site in the nation. During wartime, the camp's mission is to serve as a major independent mobilization station of the United States Army Forces Command (FORSCOM). Camp Shelby Joint Forces Training Center is the largest reserve component training site, covering 136,000 acres (550 km2), allowing up to battalion-level maneuver training, Gunnery Table 8-12, field artillery firing points and a wide range of support facilities. This is the normal Annual Training location for National Guard and Reserve units located in Mississippi, Alabama, and Tennessee. However, units from across the country use its assets to support a variety of missions. The 2nd Battalion, 114th Field Artillery conducts its gunnery training and has the bulk of its combat equipment stored in the Mobilization and Annual Training Equipment Site (MATES) located there.

The 172nd Airlift Wing is a unit of the Mississippi Air National Guard, stationed at Allen C. Thompson Field Air National Guard Base, Mississippi. If activated to federal service, the Wing is gained by the United States Air Force Air Mobility Command.