Promise to a Dead Man — Kent Conwell

But, when he climbed down off his bay in front of Roche's saloon, he landed in enough trouble to forever change his life. He hadn't counted on greedy Yankee carpetbaggers who were saddling local ranchers with usurious taxes to steal land for pennies on the dollar, especially since one of the ranches belonged to his dead partner's family. Knowing he had a battle on his hands, he hunkered down for the fight.

Outgunned ten to one, Davy Nelson fought back the way he learned in the Confederate Cavalry: hit and run, decimate the enemy, force them into fatal mistakes. And do it quick---before they hang you.