Nez Perce flight through Yellowstone
The Nez Perce Native Americans fled through Yellowstone National Park between August 20 and Sept 7, during the Nez Perce War in 1877. As the U.S. army pursued the Nez Perce through the park, a number of hostile and sometimes deadly encounters between park visitors and the Indians occurred.
Source: Wikipedia — Nez Perce flight through Yellowstone (CC BY-SA 4.0)