And, as Paul Harvey used to say: Here is the rest of the story. A girl in the village had been impregnated by Custer and bore him a daughter with blonde hair. When he abandoned her, she became unmarriageable and an outcast. Whether she was killed in the massacre, I do not recall. THEN, Custer backed up Chivington much later. One Cheyenne warrior when to Little Big Horn with the specific intent of killing Custer and, about 25 years later, claimed/admitted his success.
You may be confusing two different fights - both of which included Black Kettle. The Sand Creek fight occurred during the Civil War, so Custer was very busy back east fighting Confederates at that time and was not in the neighborhood. If I remember correctly, Black Kettle was at Sand Creek when the fight happened.
A few years later, at the Washita, Black Kettle was killed when the 7th Cav (led by Custer this time)attacked his village.
Black Kettle and his band were peaceful, but all along that very same river were encamped other bands that absolutely were not peaceful - go ask Major Elliot.
I read a book by a trooper that was severely wounded and nearly killed at the Washita. According to him, the cav scouts cut the trail of some indians which they followed back to Black Kettle's camp. The indians in that area were supposed to be hostile. The cavalry reached the camp at night and set up for the attack in the predawn darkness. The Army attacked at first light, so there was no way of knowing Black Kettle was around until it was too late.
Chivington's attack was immediately condemned far and wide, there were several investigations in which he was reviled in no uncertain terms, he was forced to resign from the militia, he was forced out of politics and he ended up hauling freight in Nebraska. He wasn't hanged, but he was never celebrated for what he did at Sand Creek.