The legendary Buffalo Soldiers, four army regiments of former slaves, were vital in taming the American frontier. The Tenth Cavalry of African American troopers rode across the Colorado plains to battle the Cheyennes and rescue wounded, starving soldiers at Beecher Island on the Arikaree River. Under the cover of darkness, the Ninth Cavalry aided besieged troops pinned down by Ute sharpshooters at Milk Creek. They drove off Cheyenne Dog Soldiers attacking...