I wasn't tracking that Clarkson's Regiment was the 13th Arkansas, I thought it had a missouri designation. I was tracking that the remenants of Clarkson's battalion was reorganized under a LTC Buster and designated as the 15th Arkansas Cavalry Battalion.

Organized on September 20, 1863 for service in the Indian Territory by transferring the four Arkansas companies from Clark's Missouri Infantry Regiment and placing them under the command of Lt. Col. Michael W. Buster in accordance with the provisions of Special Order #171, District of Arkansas, Dept. of the Trans-Mississippi. Dismounted to serve as infantry on June 11, 1864 by order of General Kirby Smith. No further record exist for this battalion after that point.