After crushing the Sioux Nation in an 1862 war of Yankee aggression in Minnesota, POTUS Abraham Lincoln approved the largest racially-motivated mass execution in US history, hanging 38 Sioux braves. With this reprisal completed, he allowed the "free soil" state of Minnesota to deport the remaining Sioux from their own land. The Union government subsequently confined them in what would now be considered concentration camps, where many died from disease, exposure, & malnutrition.
In 1864, Union cavalry under Col. John Chivington massacred nearly 170 Cheyenne men, women, & children at Sand Creek, Colorado. By failing to punish or even rebuke the perpetrators of this atrocity, Lincoln effectively enabled the massacre. Thus, proper condemnation must be declared against this genocidal behavior.