After sustaining heavy casualties at the Battle of the Big Hole on August 9–10, the Nez Perce proceeded southward though Montana, crossed into Idaho again at Bannock Pass, and descended into the valley of the Lemhi River. The Nez Perce were aware that the U.S. army was pursuing them and, to confound the army, they took a circuitous route less familiar to them than their usual direct route to the Montana Great Plains. During this section of their retreat, their guide and the leader of their march was a half-Nez Perce, half-French man of several names, the most common being Poker Joe. The White settlers in the Lemhi Valley had been warned that the Nez Perce might be coming their way and most of them had fled to the town of Lemhi.