Colorado War: Colorado volunteers led by Colonel John Chivington massacre at least 150 Cheyenne and Arapaho noncombatants at Sand Creek inside Colorado Territory.

The Colorado War was an Indian War fought in 1864 and 1865 between the Southern Cheyenne, Arapaho, and allied Brulé and Oglala Lakota peoples versus the U.S. Army, the Colorado militia, and white settlers in Colorado Territory and adjacent regions. The Kiowa and the Comanche played a minor role in…