Dead man's hand / David Nix.

[Jake Paynter Series book 2 Devil's ride West].

Jake Paynter is a doomed man. Haunted by an abusive childhood and his participation in atrocities of the Civil War, he seeks the isolation of the Plains Cavalry as a white officer for an all-Black buffalo soldier troop. Now, he is in irons and certain to be hanged for killing his captain after refusing an inhumane order. Despite his best efforts to maintain isolation, he starts to make friends on his journey to trial. The people of the wagon train begin looking to Paynter for leadership, and he reluctantly falls into the role. The opportunity to escape arises when the wagon train is attacked by bandits, but Paynter's growing ties to the travelers compel him to stay. As his trial approaches, Paynter must lean on his friends for salvation, but the laws of the west are swift and harsh, and a grueling confrontation with his past is on the horizon.