A few of these refugees from the war fled to Canada, but more than 4,000 congregated in the summer of 1863 in a large encampment in present-day Kidder County, North Dakota.

[3] Sibley's ponderous column proceeded very slowly northwestward, hampered by drought, heat, and a lack of potable water.

After a month of travel without having seen a single Indian, Sibley was informed by a group of buffalo hunters, mostly Métis Chippewa, of the location of a large Santee encampment of 600 lodges.

With a stripped-down army of 2,056 men – 1,436 infantry, 520 cavalry, and 100 artillery plus 60 mixed blood and Sioux scouts – Sibley located the Santee encampment on July 24.

An army surgeon, Dr. Josiah S. Weiser, approached Big Mound to greet several Indian friends, but was suddenly shot and killed by Tall Crown, a follower of Inkpaduta.

Sibley sent forward two companies of Mounted Rangers to drive the Indians away from Big Mound and supported them with more soldiers and a six-pounder cannon.

Most of Sibley's infantry devoted themselves to destroying the large quantities of jerky, buffalo robes, cooking utensils, and other goods left behind by the Sioux in their hasty flight.