The congressional investigation of Sand Creek produced extensive sworn testimony from military officers, some of whom had participated and some of whom had refused to participate.

This testimony, preserved in the official record, is among the most important primary sources for what happened at Sand Creek and for the specific decisions that produced it.

Fort Lyon’s correspondence records include communications from the weeks before Sand Creek — letters and dispatches that document both the Cheyenne leaders’ efforts to seek protection and the military commanders’ responses.

These records make clear what promises were made and how they were violated.

The paper trail that Black Kettle’s efforts generated — through his attendance at treaty councils, his visits to military posts, his meetings with commissioners and generals — is one of the most detailed records of any Indigenous leader’s diplomatic activity in this period.