Raiders and war parties didn’t operate in deep winter because the conditions made long-distance travel too difficult and dangerous.

The American military’s winter campaign strategy, developed by Sheridan, was specifically designed to exploit this vulnerability.

By attacking in winter, when the plains peoples were concentrated and immobile, when their horses were weakened, and when they had no mobility to escape, the Army could achieve the comprehensive destruction of entire communities that was the point of the campaign.

Black Kettle’s band was in exactly the kind of winter camp location that made sense for plains peoples in November.

They were in a river valley, sheltered from the weather, with grass available for their horses.