The 39th Infantry Division was an infantry formation of the Army National Guard, originally formed as the 18th Division in 1917. The division consisted of troops from Arkansas, Louisiana, and Mississippi. After training at Camp Beauregard, Louisiana, the division was deployed to France but did not see combat before the end of World War I. In July 1923 the division was re-designated as the 31st Infantry Division. The 39th Infantry Division was reactivated after World War II with troops from Louisiana and Arkansas and its headquarters in Louisiana. In 1967, the 39th Infantry Division was reorganized to become the 39th Infantry Brigade (Separate). Its headquarters was in Little Rock and the unit consisted entirely of troops from Arkansas.

The Army National Guard (ARNG), in conjunction with the Air National Guard, is an organized militia force and a federal military reserve force of the United States Army. They are simultaneously part of two different organizations: the ARNG of each state, most territories, and the District of Columbia, as well as the federal ARNG, as part of the National Guard as a whole. It is divided into subordinate units stationed in each state or insular area, responsible to their respective governors or other head-of-government.