Buffalo Soldiers (1997)

At the end of the Civil War, Washington Wyatt (Danny Glover) is liberated from slavery and signs up as a sergeant in the first all African-American U.S. Army unit. Once assigned to the unit, Wyatt realizes that both his commanding officer (Tom Bower) and his colonel (Bob Gunton) are racists. Tensions rise when Wyatt arrests Capt. Draper (Robert Knott) and several other Texas Rangers, all of whom are white. Later, Wyatt and his fellow soldiers set out to capture a hostile Indian chief.