In that vision, Sitting Bull had seen soldiers falling from the sky like grasshoppers, falling upside down into the Lakota camp.

The holy man interpreted this as a promise: if the people stayed together and remained spiritually prepared, they would triumph over the soldiers who were coming.

The camp that assembled on the Greasy Grass — estimates of its size range from ten thousand to fifteen thousand people, with perhaps three thousand to four thousand warriors — was a response to that vision, and to the escalating military pressure the U.S. government had been applying to force the Lakota onto reservations.

The summer of 1876 was also a moment of specific political crisis.