Ken,
A quick search at findagrave shows this man's grave and gives his regiment as the 115th AL, Co. A. However, this regiment isn't listed with the NPS Soldier and Sailor listing. A search for "James E. Warren" on footnote brings up the 1st AL Infantry. One of the counties in AL that this regiment was formed from is Tallapoosa. In the 1860 census, there was a James Warren, born 1844, living in Tallapoosa County. There are numerous possibilities but this looks feasible. Good luck!