Custer's cavalry was escorting the Northern Pacific Railway survey party along the Yellowstone River in the summer of 1873. Colonel David S. Stanley commanded the entire expedition: 1,300 soldiers, two artillery pieces, 275 mule-drawn wagons, and 353 civilian surveyors. Twenty-seven Indian and mixed-blood scouts provided reconnaissance. The railroad meant everything to the nation's expansion and nothing good to the Lakota, Cheyenne, and other tribes who depended on the buffalo herds that the iron horse would inevitably scatter. Just a week earlier, on August 4, Lakota warriors had attacked the column at Honsinger Bluff, killing two officers and a veterinarian.

The ground where Custer camped had a complicated history. The Treaty of Fort Laramie in 1851 had designated this area as Crow Indian country, a fact the Lakota themselves acknowledged. But by 1868, the Crow had agreed to a smaller reservation, and the land north of the Yellowstone, including Pease Bottom, became U.S. territory. The Lakota who attacked Custer that morning were themselves on land they had taken from other tribes. The conflict between the United States and the buffalo-seeking Lakota was, in essence, a collision between two expanding empires.

Sitting Bull's village numbered between 400 and 500 lodges, fielding an estimated 800 to 1,000 warriors. Among their leaders were Gall and the war chief Rain in the Face of the Hunkpapa, Crazy Horse of the Oglala, and warriors of the Miniconjou and Cheyenne. As dawn broke, warriors crossed the Yellowstone above and below Custer's position and attacked from multiple directions. Private John Tuttle of Company E fell in the morning fighting after killing at least three warriors across the river. The 7th Cavalry defended their camp, then counterattacked with a charge that drove the warriors eight miles from the battlefield.

The battle cost the army one killed and four wounded, plus at least one horse. Second Lieutenant Charles Braden suffered a shattered thigh that would keep him on sick leave until his retirement in 1878; he was posthumously awarded the Distinguished Service Cross in 1925. Custer estimated Lakota losses at forty warriors. Colonel Stanley's column appeared during the engagement and hurried to support, though the battle was already turning. For the Lakota, this was a setback but not a defeat. For Custer, it was a victory that may have bred overconfidence. Three summers later, along the Little Bighorn just south of here, that confidence would prove fatal.