The 1866 battle on Wyoming’s Bozeman Trail that became a major Lakota and Cheyenne victory was the Fetterman Fight.
The battle took place on December 21, 1866, near Fort Phil Kearny in the Dakota Territory, in the region that is now Wyoming. Captain William J. Fetterman led a force of 80 U.S. soldiers and civilians in pursuit of Native decoys. The soldiers were drawn away from the fort and surrounded by a much larger force of Lakota, Cheyenne, and Arapaho warriors.
Every member of Fetterman’s command was killed. The defeat shocked the United States and demonstrated the danger of protecting emigrant routes through contested Plains territory. The Bozeman Trail crossed hunting grounds that Native peoples opposed opening to settlers and military traffic.
The fight is often confused with the Wagon Box Fight and Hayfield Fight, which occurred near Fort Phil Kearny in 1867. Those later encounters ended differently, with U.S. troops holding defensive positions against larger Native forces.