On a hot summer's day in Montana, a daring frontier cavalry officer, Powhatan Henry Clarke, died at the height of his promising career. A member of the U.S. Military Academy's Class of 1884, Clarke graduated dead last, and while short on academic application, he was long on charm and bravado. Clarke obtained a commission with the black troops of the Tenth Cavalry, earning his spurs with these "Buffalo Soldiers." He evolved into a fearless...