At least you've plugged a hole in my investigation - can't be the same one!! My John M. DAVIS was born in 1847, originally from Georgia, settled in Titus County, TX. We know he was in the Civil War, but being so young he either lied about his age or enlisted late in the war.
Unfortunaltely, chasing a DAVIS is like chasing a SMITH. I have other possible links for my John M. DAVIS in the 10th TX Cavalry, 9th TX Infantry, and Chamber's Battalion.