Franklin was a northern province in Detina. It seceded with "King" Geoffrey during the Detinan Civil War. Obviously, the Army of Franklin comes Franklin, but due to the inept commands of Count Thraxton the Braggart and General Bell the actual province was lost by the army to the southrons and the army forced away from it province.
Franklin is analogous to the State of Tennessee. In reality, the State of Franklin was a short lived autonomous territory that existed from 1784 to 1788. It never received recognition from the United States government, and in time, the territory became part of eastern Tennessee.