In 1864 Black Kettle attempted to bring fighting between Cheyenne warriors and soldiers to an end and in one incident saved the lives of First Lieutenant George Eayre and his men. Black Kettle had great difficulty controlling the young warriors and after negotiations with Major Scott Anthony at Fort Lyon he took his followers to Sand Creek.
To protect the peaceful members of the Cheyennes tribes from attack, Black Kettle was given an American Flag to fly to show the camp was friendly. Despite taking these precautions 1,000 Colorado Volunteers attacked the camp on 29th November, 1864, and killed around 200 people, three-fourths of them being women and children.
Black Kettle took the survivors to the south bank of the Arkansas River where they settled with the Arapaho, Kiowa and Comanche who were determined not to get involved in the fighting. On 14th October, 1865, he signed the Little Arkansas River Treaty.
In the winter of 1868 Black Kettle and his people were camped on the Washita River. On 27th November, 1868, the camp was attacked by Major General George A. Custer and the Seventh Cavalry. Custer later claimed that his men killed 103 warriors. However, the majority of the victims were women and children. This action was highly controversial as the Cheyenne were not at war against the Americans at this time. General Harney pointed out: "I have worn the uniform of my country 55 years, and I know that Black Kettle was as good a friend of the United States as I am."
Black Kettle and his wife were both killed in the attack.