Wolf Mountain by L. J. Martin

Amazon

Their family had carved a homestead from a fierce Montana mountainside. Now Colin and Kevin McQuade must get 200 head of cattle down to the 5th Infantry at the Tongue River, even though the Sioux are riding wild in the land. With winter bearing down, the McQuades prepare to fight their way south. But they aren't counting on a slick St. Louis gambler joining the drive. Or a beautiful young woman pursued by a rich man's thugs. Or the horror that is about to strike in Rocky Butte. Another wild western in The Montana Series from acclaimed writer L. J. Martin