There is a Seth Davis listed with Unit
11th (Spaight's) Battalion Vol., Company A.

Here is a website with a history of Spaight's Battalion, not to be confused with Speight's Regiment/Brigade.

http://www.wtblock.com/wtblockjr/Spaight.htm

Last Name First Name Unit Sub Unit Rank
Davis, N. Cav. Terry's Regt. Co.A
Davis, N.T. 27th Cav. Co.G
Davis, Nathan 11th Inf. Co.E Cpl.
Davis, Nathan 17th Cav. Co.E
Davis, Nathan 36th Cav. Co.I Sgt.
Davis, Nathan T. 12th Inf. Co.I .I