After news of the massacre spread, Evans and Chivington were forced to resign from their appointments. But neither faced criminal charges, and the government refused to compensate the victims or their families in any way. Indeed, Sand Creek was just one part of a campaign to take the Cheyenne’s once vast land holdings across the region. A territory that had hardly any white communities in 1850 had, by 1870, lost many Indians, who were pushed violently off the Great Plains by white settlers and the federal government.

These and other campaigns amounted to what is today called ethnic cleansing: an attempted eradication and dispossession of an entire indigenous population. Many scholars suggest that such violence conforms to other 20th-century categories of analysis, like settler colonial genocide and crimes against humanity.

Sand Creek, Bear River and the Long Walk remain important parts of the Civil War and of American history. But in our popular narrative, the Civil War obscures such campaigns against American Indians. In fact, the war made such violence possible: The paltry Union Army of 1858, before its wartime expansion, could not have attacked, let alone removed, the fortified Navajo communities in the Four Corners, while Southern secession gave a powerful impetus to expand American territory westward. Territorial leaders like Evans were given more resources and power to negotiate with, and fight against, powerful Western tribes like the Shoshone, Cheyenne, Lakota and Comanche. The violence of this time was fueled partly by the lust for power by civilian and military leaders desperate to obtain glory and wartime recognition.

Expansion continued after the war, powered by a revived American economy but also by a new spirit of national purpose, a sense that America, having suffered in the war, now had the right to conquer more peoples and territories.

The United States has yet to fully recognize the violent destruction wrought against indigenous peoples by the Civil War and the Union Army. Connor and Evans have cities, monuments and plaques in their honor, as well as two universities and even Colorado’s Mount Evans, home to the highest paved road in North America.