Chapter 26 Outline The Clash of Cultures on the Plains Plains Indians: often fought one another, very scattered, not really organized beyond nomadic family groups Fort Laramie and Fort Atkinson: US tried to make peace treaties with various tribes, marked beginning of reservation system Buffalo Soldiers: 1/5 of US Army were black at the time Receding Native Population Colonel J. M. Chivington: his militia massacred 400 Indians at Sand Creek, CO Fetterman massacre: 1866 Sioux war party ambushed Fetterman?s troop and killed all Treaty of Fort Laramie: US abandoned Bozeman Trail, gave Sioux the Great Sioux Reservation