The Nez Perce in Yellowstone Park was the flight of the Nez Perce Indians 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. Eventually, the army's pursuit forced the Nez Perce off the Yellowstone plateau and into forces arrayed to capture or destroy them when they emerged from the mountains of Yellowstone onto the valley of the Yellowstone River.