Dull Knife Fight
1876 CE.
Shown on the map at 43.541°, -107.539°.
The Dull Knife Fight, or the Battle on the Red Fork, part of the Great Sioux War of 1876, was fought on November 25, 1876, in present-day Johnson County, Wyoming between soldiers and scouts of the United States Army and warriors of the Northern Cheyenne. The battle essentially ended the Northern Cheyennes' ability to continue the fight for their freedom on the Great Plains.
Text from the Wikipedia article Dull Knife Fight, licensed CC BY-SA 4.0.