Anthony, "McMurtrey's battalion" was actually the remnants of the 2nd Regiment Arkansas Cavalry, which was decimated in Price's Missouri Campaign in the Fall of 1864, reduced to a battalion, and designated as the 18th Battalion Arkansas Cavalry, under command of Lieut. Col. Elisha Lawley McMurtrey, about late October 1864. I haven't been able to determine how the companies were left in the reorganization.

There are no known muster rolls for the battalion, but it was composed of the survivors of the 2nd Arkansas Cavalry and whatever recruits it managed to obtain between November 1864 and May 1865.