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.

Major General Grenville M. Dodge ordered the Powder River Expedition as a punitive campaign against the northern plains tribes in the heart of their territory.
Brigadier General Patrick E. Connor was chosen to lead the expedition.
Dodge ordered Connor to "make vigorous war upon the Indians and punish them so that they will be forced to keep the peace."
The campaign was one of the last Indian wars campaigns carried out by United States Volunteers.

Connor's strategy was for three columns of soldiers to march into the Powder River Country.
The "Right column", composed of 1,400 Missourians and 140 wagons commanded by Colonel Nelson D. Cole, was to march from Omaha, Nebraska and follow the Loup River westward to the Black Hills, meeting up with Connor near the Powder River.
The "Center Column", consisting of 600 Kansas cavalrymen led by Lieutenant Colonel Samuel Walker, was to head north from Fort Laramie and traverse the country west of the Black Hills.
The "Left" and "West" Columns of 675 men, personally commanded by Connor and composed of soldiers from California, Iowa, Michigan, Nebraska and Ohio, along with Indian scouts and a wagon train, would move toward the Powder River with the goal of establishing a fort near the Bozeman trail.
All three columns were to unite at the new fort.

Connor's orders to his commanders were as follows, "You will not receive overtures of peace or submission from Indians, but will attack and kill every male Indian over twelve years of age."
Connor's superiors, Generals John Pope and Dodge attempted to countermand this order, but it was too late, as the three columns had already departed and were out of contact.

The expedition was troubled from the start.
The number of men to be involved in the campaign was reduced from 12,000 to less than 3,000 because many soldiers were mustered out of the army at the end of the American Civil War.
The remaining volunteers were "mutinous, dissatisfied, and inefficient."
The companies of the 6th Michigan Volunteer Cavalry Regiment commanded by Colonel James H. Kidd had recently been transferred from the Civil War battlefields of Virginia, and most of Cole's and Walker's men had been active in the Western Theater during the last years of the war.
Few of the men and officers had any experience fighting Indians or traveling on the Great Plains.
Procuring supplies was also a problem.
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.
Major General Grenville M. Dodge ordered the Powder River Expedition as a punitive campaign against the northern plains tribes in the heart of their territory. Brigadier General Patrick E. Connor was chosen to lead the expedition. Dodge ordered Connor to "make vigorous war upon the Indians and punish them so that they will be forced to keep the peace." The campaign was one of the last Indian wars campaigns carried out by United States Volunteers.
Connor's strategy was for three columns of soldiers to march into the Powder River Country. The "Right column", composed of 1,400 Missourians and 140 wagons commanded by Colonel Nelson D. Cole, was to march from Omaha, Nebraska and follow the Loup River westward to the Black Hills, meeting up with Connor near the Powder River. The "Center Column", consisting of 600 Kansas cavalrymen led by Lieutenant Colonel Samuel Walker, was to head north from Fort Laramie and traverse the country west of the Black Hills. The "Left" and "West" Columns of 675 men, personally commanded by Connor and composed of soldiers from California, Iowa, Michigan, Nebraska and Ohio, along with Indian scouts and a wagon train, would move toward the Powder River with the goal of establishing a fort near the Bozeman trail. All three columns were to unite at the new fort.
Connor's orders to his commanders were as follows, "You will not receive overtures of peace or submission from Indians, but will attack and kill every male Indian over twelve years of age." Connor's superiors, Generals John Pope and Dodge attempted to countermand this order, but it was too late, as the three columns had already departed and were out of contact.
The expedition was troubled from the start. The number of men to be involved in the campaign was reduced from 12,000 to less than 3,000 because many soldiers were mustered out of the army at the end of the American Civil War. The remaining volunteers were "mutinous, dissatisfied, and inefficient." The companies of the 6th Michigan Volunteer Cavalry Regiment commanded by Colonel James H. Kidd had recently been transferred from the Civil War battlefields of Virginia, and most of Cole's and Walker's men had been active in the Western Theater during the last years of the war. Few of the men and officers had any experience fighting Indians or traveling on the Great Plains. Procuring supplies was also a problem.
Powder River Expedition (1865)