After several years of fighting against the U.S. Army, which was itself
beleaguered by the Civil War, the Cheyenne were forced to surrender in
September 1864.  Meeting with Colonel John M. Chivington at Camp Weld
(pictured above) in September, Black Kettle and his tribe assumed a peace
agreement had been reached, and they camped at Sand Creek, forty miles
away, under the impression they were under the protection of Fort Lyon. 
Among the group were five hundred women and children and only two hundred
warrior.  Two months later, on November 29, 1864, Chivington led his
Cavalry of 750 in a surprise attack on the Indians, killing 105 women and
children and 28 men, as well as mutilating the dead and wounded.  These
events signified a terrible betrayal for chiefs willing to negotiate
peace with the military.