He died in 1889 at the age of forty-eight.

Mackenzie is remembered in military history as one of the most effective Indian War commanders — a characterization that reflects his tactical and strategic capabilities and does not assess the moral dimensions of the campaigns he conducted.

The destruction of the camps and the horse slaughter at Palo Duro Canyon were, within the military culture and policy framework of the 1870s, entirely proper and commendable actions.

The question of whether that framework and those policies were themselves just is a separate question from the question of whether Mackenzie executed his orders effectively.