Released during the height of the Vietnam War against the backdrop of the courts martial stemming from the My Lai massacre, it provided the first motion picture account of one of the most infamous incidents in the history of the American frontier, in which Colorado state militia troops under Colonel John M. Chivington massacred an undefended village of Cheyenne and Arapaho on the Colorado eastern plains.

The account of the massacre is fictionalized in the context of a longer story involving the escape of white survivors from an earlier massacre of U.S. Cavalry troops by Indians. The names of all real person characters were also changed.