Cosby A. Barnes is a female, married to Fielding Barnes located in Pettis Twshp, Platte Co., Missouri in 1870. Listed as well is her 2 year old son George T. Barnes who is buried next to her in Denlow Cemetery.
I can find little else on this family, George T is listed in Douglas Co 1900 census with wife Mary and young son Albert aged 1.
Suffice it to say I doubt Cosby A had any Civil War service.
John R.