This letter, written by T. Moonlight, Colonel of the 11th Kansas Cavalry, states that the purpose of this military investigation, among other things, was to ascertain if Colonel John Chivington, commander of the 1st Colorado Cavalry, had followed the "recognized rules of civilized warfare." These hearings, which were not a formal military trial, were held in Denver beginning on February 9, 1865. The massacre of Cheyenne Indians at Sand Creek, Colorado Territory, had occurred in November 1864. The letter is part of a larger report containing evidence obtained at this hearing, titled Report of the Secretary of War, Communicating, In compliance with a resolution of the Senate of February 4, 1867, a copy of the evidence taken at Denver and Fort Lyon, Colorado Territory, by a military commission, ordered to inquire into the Sand Creek massacre, November, 1864.