He led a rear action against a Confederate supply train in the Battle of Glorieta Pass that had the effect of ending the Confederacy's campaigns in the Western states, and was then appointed a colonel of cavalry during the Colorado War.

Colonel Chivington gained infamy[1] for leading the 700-man force of Colorado Territory volunteers responsible for one of the most heinous atrocities in American military history: the November 1864 Sand Creek massacre.

An estimated 70 to 600 peaceful Cheyenne and Arapaho – about two-thirds of whom were women, children, and infants – were murdered and mutilated by Col. Chivington and the volunteer troops under his command.

Chivington and his men also took scalps and many other human body parts as trophies, including unborn fetuses, as well as male and female genitalia.

His name appears as a member of the executive board of Colorado Seminary, the historic precursor of the University of Denver and the Iliff School of Theology.

His name also appears in the incorporation document issued by the Council and House of Representatives of the Colorado Territory, which was approved by then governor John Evans.

[6] When the Civil War broke out, Colorado Territorial Governor William Gilpin offered him a commission as a chaplain, but Chivington refused it, saying he wanted to fight.

During Confederate General Henry Hopkins Sibley's offensive in the East Arizona and New Mexico territories, Chivington led a 418-man detachment to Apache Canyon.

Chivington earned high praise for his decisive stroke at Johnson's Ranch, even though his discovery of the Confederate supply train was accidental.

Critics have suggested that had Chivington returned quickly to reinforce Slough's army when he heard gunfire, his 400 extra men might have allowed the Union to win the battle.

His superiors expressed enough concern that he was putting his political interests ahead of his duties that he had to write Major General Samuel Ryan Curtis, commander of the Department of Kansas, a letter of reassurance.

Kill and scalp all, big and little; nits make lice.Following the Hungate massacre in June 1864, tensions between settlers and Indians rose.

The latter was granted, and Chivington formed the 3rd Colorado Cavalry Regiment from a group of volunteers who largely lacked combat experience,[11] to protect Denver and the Platte road.

[14] In the fall of 1864, Major Edward Wynkoop received a letter from Black Kettle requesting a peace council and an exchange of prisoners, and Wynkoop succeeded in holding a conference with multiple Cheyenne and Arapaho chiefs, including Black Kettle and Left Hand, and securing the release of some prisoners who had been taken during earlier Dog Soldier raids.

Known as the Camp Weld Conference,[15] it resulted in Evans making an offer of protection to those Indians who would surrender to Wynkoop at Fort Lyon.

The chiefs agreed, and, after gathering their peaceful tribes, camped about 40 mi (64 km) north of the fort, at Big Sandy Creek.

In November, Chivington and his 800 troops of the 1st and 3rd Colorado cavalry regiments along with a company of 1st New Mexico Volunteer Infantry marched to Fort Lyon.

Upon reaching the fort, with Wynkoop and Anthony still present, Chivington posted guards outside so no one could leave or enter and placed soldiers known to have helped the Indians under arrest.

"Any man that would take part in the murders, knowing the circumstances as we do", said Captain Silas Soule, "is a low-lived cowardly son of a bitch."

On the way back from the site, he wrote an official account of a long march through snow to a battle against fierce and dedicated opposition won by troops who performed "nobly".

However, the testimony of Soule, Cramer and his men contradicted their commander and resulted in a U.S. Congressional investigation into the incident, which concluded that Chivington had acted wrongly.

[22] An Army judge publicly stated that the Sand Creek massacre was "a cowardly and cold-blooded slaughter, sufficient to cover its perpetrators with indelible infamy, and the face of every American with shame and indignation".

Wearing the uniform of the United States, which should be the emblem of justice and humanity; holding the important position of commander of a military district, and therefore having the honor of the government to that extent in his keeping, he deliberately planned and executed a foul and dastardly massacre which would have disgraced the verist [sic] savage among those who were the victims of his cruelty.

Having full knowledge of their friendly character, having himself been instrumental to some extent in placing them in their position of fancied security, he took advantage of their in-apprehension and defenceless [sic] condition to gratify the worst passions that ever cursed the heart of man.

Whatever influence this may have had upon Colonel Chivington, the truth is that he surprised and murdered, in cold blood, the unsuspecting men, women, and children on Sand creek, who had every reason to believe they were under the protection of the United States authorities.Chivington resigned from the army in February 1865.

He argued that his expedition was a response to Cheyenne and Arapaho raids and torture inflicted on wagon trains and white settlements in Colorado.

He also overlooked how the massacre caused the Cheyenne, Arapaho, and Sioux to strengthen their alliance and to accelerate their raids on white settlers.

Because of Chivington's position as a lay preacher, in 1996 the General conference of the United Methodist Church expressed regret for the Sand Creek massacre.

[29] In 2005, the City Council of Longmont, Colorado, agreed to change the name of Chivington Drive in the town following a two-decade campaign.