Warren introduces bill to revoke Medals of Honor awarded for Wounded Knee Massacre The bill was introduced on the eve of Thanksgiving.

Sen. Elizabeth Warren, D-Mass., introduced legislation on Wednesday moving to rescind 20 Medals of Honor awarded to U.S. soldiers who murdered hundreds of Lakota Indians in the Wounded Knee Massacre of 1890.

Years on, it's still considered a one of the more brutal pages in U.S. history -- many of those slaughtered were women and children.

The Remove the Stain Act was co-sponsored by Warren's fellow Democratic 2020 contenders and Senate colleagues Bernie Sanders of Vermont and Kamala Harris of California, in addition to Sens. Jeff Merkley, D-Ore., Ron Wydan, D-Ore., and Patrick Leahy, D-Vt.

It's the Senate-side version of a bill introduced in the House this June, among others, by Rep. Deb Haaland, D-N.M., one of the first Native American women to serve in Congress. She's endorsed Warren and recently was named as one of her three female campaign co-chairs. Warren first committed to the bill in August.

"Removing these medals is the first step of creating justice and equality for Native peoples," said OJ Semans, co-executive director of Four Directions, an organization that helped draft the House bill, and a member of the Rosebud Sioux Tribe. "As long as those medals are in place, the United States is saying that for 129 years we were right -- and we'll continue to condone this."

The Senate bill comes on the eve of Thanksgiving, itself already a contentious holiday for indigenous peoples. It also comes amid President Donald Trump's controversial intervening in the case to protect Eddie Gallagher from Navy efforts to eject him from the SEALS.

The Medal of Honor is the nation's highest military honor, awarded for "gallantry beyond the call of duty." Native American activists have long urged the medals to be withdrawn, calling them "medals of dishonor."

"Allowing any Medal of Honor, the United States' highest and most prestigious military decoration," the bill reads, "to recognize a member of the Armed Forces for distinguished service for participating in the massacre of hundreds of unarmed Native Americans is a disservice to the integrity of the United States and its citizens and impinges on the integrity of the award and those who have earned the Medal since."

The introduction of the bill some 130 years later is largely symbolic, but like many honorariums, whether medals or designated holidays, symbols can be powerful.

The National Congress of American Indians has been pushing for the medals to be revoked for years, in 2001 passing resolutions condemning the awards and in 2007 requesting Congress rescind or make the medals null and void.

Native American voters have expressed it's deeply important, and it was a central focus of the forum in Cedar Rapids this summer where Warren took the moment to apologize for the issue of her own past controversial claims of Native American heritage, and subsequent DNA test.

"The horrifying acts of violence against hundreds of Lakota men, women and children at Wounded Knee should be condemned, not celebrated with Medals of Honor," Warren said in a statement put out by her Senate office, acknowledging the "profoundly shameful event."

"The massacre of innocents," said Merkley, "could not be farther from heroism, and I hope this bill helps set the record straight."

ABC News' Cheyenne Haslett contributed to this report.