The Haun's Mill massacre was an event in the history of the Latter Day Saint movement. It occurred on October 30, 1838 when a mob/militia unit from Livingston County, Missouri, attacked a Mormon settlement in eastern Caldwell County, Missouri, United States, after the Battle of Crooked River. By far the bloodiest event in the 1838 Mormon War in Missouri, it has long been remembered by the members of the Latter Day Saint movement.