Found Captain J. M. McMillian listed as the captain of Co. "D" of Murray's 4th Tn Cav. The following excerpts are from the regimental history in Tennesseeans in the Civil War-

"J. M. MCMillan, J. J. Amonett, Co. "D". Organized November 11, 1861 at Livingston, Overton County, as James W. McHenry's Company, "Brown Rangers." Became 2nd Co. "C", 1st Confederate Cavalry."

"On December 12, lost Captain J. M. McMillan in skirmish near Nolensville."

Perhaps the 8th carving was added later by a confused someone as a commeration. I'll try and check his CSR.