Missouri Executive Order 44
Missouri Executive Order 44 (known as the Mormon Extermination Order) was a state executive order issued by Missouri Governor Lilburn Boggs on October 27, 1838, in response to the Battle of Crooked River. The clash had been triggered when a state militia unit from Ray County seized several Mormon hostages from Caldwell County, and the subsequent attempt by the Mormons to rescue them.
Source: Wikipedia — Missouri Executive Order 44 (CC BY-SA 4.0)