The Colorado War was fought from 1863 to 1865 and was an Indian War between the Cheyenne and Arapaho tribes and white settlers and militia in the Colorado Territory and adjacent regions. The Kiowa and the Comanche played a minor role in actions that occurred in the southern part of the Territory along the Arkansas River, while the Sioux played a major role in actions that occurred along the South Platte River along the Great Platte River Road, the eastern portion of the Overland Trail. The United States government and Colorado Territory authorities participated through the Colorado volunteers, a citizens militia while the United States Army played a minor role. The war was centered on the Colorado Eastern Plains.