29 November

The Sand Creek massacre was an atrocity in the American Indian Wars that occurred on November 29, 1864, when a 700-man force of Colorado Territory militia attacked and destroyed a peaceful village of Cheyenne and Arapaho in southeastern Colorado Territory, killing and mutilating an estimated 70–163 Native Americans, about two-thirds of whom were women and children. The location has been designated the Sand Creek Massacre National Historic Site and is administered by the National Park Service.