Throughout 1864, tensions escalated between White settlers and Native Americans on the Colorado frontier. So John Evans, the territory’s second governor, made a proclamation in June of that year, telling “friendly Indians of the Plains” to report to outposts like Fort Laramie and Camp Collins for safety and protection.

Two months later, Evans issued a decidedly darker order, authorizing all citizens of the territory to “kill and destroy, as enemies of the country, wherever they may be found … hostile Indians.”

Those proclamations led to the Sand Creek Massacre in November of that year, when U.S. troops slaughtered hundreds of Arapaho and Cheyenne — including women, children and the elderly — after several tribal chiefs went out to greet them and as dozens of other Native Americans tried to flee.

Afterward, soldiers butchered their bodies and paraded them in public.

For 157 years, Evans’s orders remained on the books.

Not anymore. On Tuesday, Colorado Gov. Jared Polis (D) signed an executive order rescinding Evans’s proclamations, saying he hopes doing so can make amends for “sins of the past.”

Polis, joined by citizens of several tribes, including the Cheyenne and Arapaho, said the proclamation never had the force of law. Evans’s decree, which Polis called a “harmful symbol of hate,” also contradicted the U.S. Constitution and the territory’s criminal codes at the time.

“We are finally addressing a wrong of the past,” Polis said.

Ernest House Jr., who served as executive director of the Colorado Commission of Indian Affairs under Polis’s predecessor, former governor John Hickenlooper, said Polis’s action is an important way to acknowledge history and move toward reconciliation, the Associated Press reported.

American society often thinks of Native Americans as “the vanishing race, the vanishing people,” House, a citizen of the Ute Mountain Ute Tribe, told the AP. When a prominent person like Polis acknowledges past wrongs, “it gives us a place that we were important and that our lives were important.”

The lead-up to the massacre was part of a period of “conflict and confusion” that became known as the Indian war of 1864, according to the National Park Service website for the Sand Creek Massacre National Historic Site.

In the spring of that year, U.S. Army volunteers made unprovoked attacks on Cheyenne villages. Native American warriors retaliated by raiding mail coaches, wagon trains and farms. In May, Colorado soldiers attacked the village of Cheyenne Chief Lean Bear, who was shot and killed while wearing a peace medal given to him by President Abraham Lincoln the year before, according to the National Park Service.

On June 11, a White family was found murdered 25 miles southeast of Denver. Their mutilated bodies were brought to the city, the Park Service notes, and publicly displayed, causing widespread panic.

“With no evidence, many Coloradans speculated that Cheyenne or Arapaho were to blame for the family’s murder[,] inciting paranoia about impending Indian attacks,” according to the Sand Creek Massacre Foundation, a nonprofit group affiliated with the national historic site.

Meanwhile, as the Civil War stretched into the West, rumors spread that the local tribes would fight for the Confederacy as “Red Rebels,” driving pro-Union White people off the plains, the foundation adds.

Then, just after dawn on Nov. 29, 1864, Col. John Chivington led the 3rd Colorado Cavalry — some 675 troops — around a prairie bend, bringing multiple Cheyenne and Arapaho camps into view. Several chiefs went out to meet the oncoming horde. One of them, Chief Black Kettle, raised a pole with white and American flags, a gesture he had been told would communicate that they were peaceful and under U.S. government protection.

There would be no protection. Chivington’s troops attacked. Over several hours, they slaughtered more than 230 people, including women and children as they tried to flee into a dry creek. About 100 others ran one to two miles upstream and quickly dug sand pits in a futile effort to protect themselves. Chivington’s soldiers followed and slaughtered many of them — some with cannons.

After the massacre, Chivington’s “Bloody Third” went northwest and “rode in triumph through the streets of Denver, displaying scalps and other body parts,” according to the foundation’s website.

The massacre sparked more violence. To investigate what happened at Sand Creek, the U.S. War Department created a special military commission, which would condemn Chivington’s actions and call for Evans’s ouster as governor. A month after the committee published its report, then-President Andrew Johnson removed Evans from office.

In 2000, Congress authorized the creation of a national historic site marking the place of the massacre. It opened to the public seven years later. In 2014, then-Gov. Hickenlooper apologized to the Cheyenne and Arapaho people on behalf of Colorado.

On Tuesday, standing at the steps of the state Capitol in Denver, Polis acknowledged the importance of those past efforts. But, he added, Evans’s proclamations “shamefully” targeted and endangered the lives of Native Americans who lived in Colorado. Formally taking them off the books does not erase that shame, the governor said, but it sends a message about the values of Coloradans in 2021 and beyond.

“We can’t change the past,” Polis said, “but we can honor the memories of those who we lost by recognizing their sacrifice and vowing to do better.”