Powder River War

Powder River Expedition
Part of the Sioux Wars, American Indian Wars
The Powder River in southeastern Montana where Cole's and Walker's columns passed in 1865.
Date July 1 to October 4, 1865 Location Powder River Country, Montana, Wyoming, South Dakota, and Nebraska, United States Result Inconclusive
Belligerents
United States	Sioux Cheyenne Arapaho
Commanders and leaders
Patrick E. Connor Nelson D. Cole Samuel Walker Frank North	Red Cloud Sitting Bull Roman Nose Dull Knife George Bent
Strength
2,300 soldiers, 179 Indian scouts, 195 civilians	~2,000 warriors
Casualties and losses
31 killed, 15 wounded	~100 killed, 10 wounded, 21 captured including women and children

The Powder River Expedition of 1865 also known as the Powder River War or Powder River Invasion, was a large and far-flung military operation of the United States Army against the Lakota Sioux, Cheyenne, and Arapaho Indians in Montana Territory and Dakota Territory. Although soldiers destroyed one Arapaho village and established Fort Connor to protect travelers on the Bozeman Trail, the expedition is considered a failure because it failed to defeat the Indians and secure peace in the region.

The Sand Creek massacre of Cheyenne people on November 29, 1864 intensified Indian reprisals and raids in the Platte River valley. (See Battle of Julesburg) After the raids, several thousand Sioux, Cheyenne and Arapaho congregated in the Powder River country, remote from white settlements and confirmed as Indian territory in the 1851 Treaty of Fort Laramie.

The Indians perceived the Bozeman Trail, blazed in 1863 through the heart of their country, as a threat. Although roads through the Indian territory were permitted by the Fort Laramie Treaty, they harassed miners and other travelers along the trail. At the Battle of Platte Bridge in July 1865, over a thousand warriors attacked a bridge across the North Platte River and succeeded in temporarily shutting down travel on both the Bozeman and Oregon Trails. After the battle, the Indians broke up into small groups and dispersed for their summer buffalo hunt. A weakness of Indian warfare was that they lacked the resources to keep an army in the field for an extended period of time.

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