On November 29, 1864, U.S. volunteer cavalry under Colonel John Chivington attacked a camp of Cheyenne and Arapaho people along Sand Creek in Colorado Territory. Many in the camp believed they were under U.S. protection and had signaled peaceful intentions. The soldiers killed a large number of men, women, and children, and mutilated some of the bodies. News of the massacre sparked outrage among some politicians, journalists, and the public. Congressional and military investigations condemned the attack, though Chivington was never court-martialed because he resigned. The massacre deepened cycles of violence on the Plains and stands as a stark example of broken promises and brutality in U.S.–Native relations.
