Best information is in the November 1861 report on the arrest of Showalter's Yuma party... War of the Rebellion records, Series I, Volume 50, Part I, pp. 31-45. On page 36, he says he's 29 from Tennessee and had previously served 18 months with the US Army in Mexico. Also claimed he had an "aged mother" back in Tennessee.n
Aside from leading Company A of the 4th Arizona... and taking over command when Showalter was court martialed in 1864... there's very little else to go on. Searches on Ancestry show a variety of candidates in Tennessee in 1850. I've never tried looking through US Army records for service before 1861 though... That might be an option.
Don