One thing I might mention on the findagrave site you looked at. Thomas McNatt's brother-in-law Wesley Hamilton's headstone also has military information.
I have a family history site on Ancestry.com which has Civil War records - American Civil War Soldiers, US Civil War Soldiers and US Civil War Soldier Records and Profiles.
For Wesley Hamilton they show Company A, 11th Alabama Cavalry, and they say this unit operated later with General Forrest. Thomas McNatt's wife says company "A" on her application. There is a "Thomas Mackey" listed in the 11th Alabama Calvary.
I have four g-grandfathers that served in the CSA. I have found quite a bit of information on all but Thomas.
Irwin Searcy was in the 26th Mississippi, Co. H
William Newton Searcy, 42nd Mississippi, Co. E
James McCutchen, 43rd Georgia, killed in action at Baker's Creek outside Vicksburg on June 16, 1863.
Just wonder if Thomas Mackey is Thomas McNatt.
Thanks for your help,
Harold