The Yellowstone Valley at Pompeys Pillar was a crossroads for travelers and wildlife and also served as a cavalry campsite and staging area. In 1873, Lt. Col. George Armstrong Custer and men of the Yellowstone Expedition, commanded by Col. David Stanley, camped in the area directly across the river. The troops protected engineers and surveyors working on the Northern Pacific Line from Indian attacks. The completed railroad would soon link the rest of the country with the North Pacific coast.