Hopalong Cassidy and the Eagle's Brood by Clarence E. Mulford

Jim Meeker came down from Montana to run Texas cattle—only to find that Hoppy’s Bar-20 ran the water. So when a trio of rustlers start a cattle war, the powder was primed, the guns cocked, and Hoppy was smack in the middle. It’s friend against friend, brother against brother, gun against blazing gun. Time’s running out, and the range is red with blood!