The Treaty of Fort Wise of 1861 was a treaty entered into between the United States and six chiefs of the Southern Cheyenne and four of the Southern Arapaho Indian tribes. A significant proportion of Cheyennes opposed this treaty on the grounds that only a minority of Cheyenne chiefs had signed, and without the consent or approval of the rest of the tribe. Different responses to the treaty became a source of conflict between whites and Indians, leading to the Colorado War of 1864, including the Sand Creek Massacre.