The Nez Perce under Chief Joseph and Looking Glass cross with their Palus allies from Idaho over Lolo Pass into Montana Territory, traveling southeast, dipping into Yellowstone National Park and then back north into Montana, roughly eleven hundred and seventy miles (eighteen hundred and eighty kilometers).

They attempt to seek refuge with the Crow Nation, but, rebuffed by the Crow, ultimately decide to try to reach safety in Canada.

A small number of Nez Perce fighters, probably fewer than two hundred, defeat or hold off larger forces of the U.S. Army in several battles.

The most notable is the two-day Battle of the Big Hole in southwestern Montana territory, a battle with heavy casualties on both sides, including many women and children on the Nez Perce side.

Until the Big Hole, the Nez Perce had held the naive view that they could end the war with the U.S. on terms favorable, or at least acceptable, to themselves.

Afterwards, the war "increased in ferocity and tempo. From then on all white men were bound to be their enemies and yet their own fighting power had been severely reduced." (Beal, Merrill D. I Will Fight No More Forever: Chief Joseph and the Nez Perce War. Seattle: U of WA Press, 1963, p. 130)