[4] An important impetus to another military campaign against the Sioux was the desire to protect lines of communication with recently discovered goldfields in Montana and Idaho.

The lifeline for the American gold miners were steamboats plying the Missouri River through the heart of Sioux territory.

Sully's First Brigade, consisting of up to 1,700 men, followed the Missouri River from its starting point at Sioux City, Iowa.

[7] Sully's two columns of soldiers united on June 29 and on July 7 he established Fort Rice on the Missouri River in North Dakota as a base, supplied by steamboat, for his military expedition.

Sully was encumbered by a wagon train of 200 miners and their families headed for the goldfields whom he reluctantly agreed to protect and escort.

[9] The Sioux in the encampment consisted mostly of Lakota (Teton) from the Hunkpapa, Sihasapa, Miniconjou, and Sans Arc bands plus Yanktonais, and a few Santees.

On the morning of July 28, scout Frank LaFramboise, a mixed-blood Santee, informed Sully of the location of the large Sioux encampment 10 miles ahead.

Killdeer Mountain was at the edge of the Dakota badlands, cut up by "deep, impassable ravines" and "high rugged hills.

"[10] Realizing that a cavalry charge would be difficult in the broken terrain Sully dismounted his soldiers and formed them in a hollow square, one mile and a quarter (2 km.)

The two sides, Sully's soldiers drawn up in a hollow square and Native forces scattered around the hills, exchanged insults at long distance.

With the first shots fired at Lone Dog, the soldiers advanced with a skirmish line and the Sioux darted at the flanks of the army, seeking weak spots.

The Sioux quickly realized that they could not hope to turn the soldiers back and they shifted their focus to packing up their tipis and equipment and protecting the flight of their women and children.

Major Alfred B. Brackett and his Minnesota Battalion on the right mounted their horses and launched a counter-charge, supported by artillery.

Beck, Paul N. Columns of Vengeance: Soldiers, Sioux, and the Punitive Expeditions 1863-1864 2013 University of Oklahoma Press Norman, OK