December 26, 1862.

The Dakota War of 1862, also known as the Sioux Uprising, (and the Dakota Uprising, the Sioux Outbreak of 1862, the Dakota Conflict, the U.S.–Dakota War of 1862 or Little Crow’s War) was an armed conflict between the United States and several bands of the eastern Sioux (also known as eastern Dakota). It began on August 17, 1862, along the Minnesota River in southwest Minnesota. It ended with a mass execution of 38 Dakota men on December 26, 1862, in Mankato, Minnesota.

Throughout the late 1850s, treaty violations by the United States and late or unfair annuity payments by Indian agents caused increasing hunger and hardship among the Dakota. Traders with the Dakota previously had demanded that the government give the annuity payments directly to them (introducing the possibility of unfair dealing between the agents and the traders to the exclusion of the Dakota). In mid-1862 the Dakota demanded the annuities directly from their agent, Thomas J. Galbraith. The traders refused to provide any more supplies on credit under those conditions, and negotiations reached an impasse. Wiki.