At dawn on November 29, 1864, a volunteer Denver militia swept down on a sleeping Cheyenne and Arapaho village camped on the Big Sandy River in southeastern Colorado, exacting brutal revenge for a year-long campaign of terror waged by tribal warrior societies on the Kansas and Colorado plains. When the smoke cleared, Colonel John M. Chivington's troops returned to Denver, waving Indian scalps and body parts to an adoring crowd that hailed their conquering...