At Sand Creek in Colorado, territorial volunteers attack encamped Cheyenne and Arapaho, killing hundreds
Some of the Cheyenne and Arapaho tribes had been carrying out sporadic guerilla warfare in the Colorado Territory but had decided to make peace. A large group under Black Kettle had gathered for that purpose at Sand Creek. There they were unexpectedly attacked by Colorado militia under Colonel John Chivington. Outnumbered, they suffered a seven hour massacre during which hundreds of Native Americans were ruthlessly killed, mostly women and children. The militia lost eight dead. (By John Osborne)
Robert Scott, Blood at Sand Creek: The Massacre Revisited (Caldwell, ID: Caxton Press, 1994), 144-150.