The Mormon War is a name sometimes given to the 1838 conflict which occurred between Latter Day Saints (Mormons) and their neighbors in the northwestern region of the US state of Missouri. This conflict is also sometimes referred to as the Missouri Mormon War to differentiate it from the Utah Mormon War (also known as the "Utah War") and the lesser known Illinois Mormon War.
The specific dates of the war are from August 6, 1838, (the Gallatin election battle) to November 1, 1838, when Joseph Smith surrendered at Far West. During the conflict 22 people were killed (3 Mormons and 1 non-Mormon at Crooked River, one Mormon prisoner fatally injured while in custody, and 17 Mormons at Haun’s Mill). An unknown number of non-combatants died due to exposure and hardship as a result of being expelled from their homes in Missouri.
The conflict was preceded by the eviction of the Mormons from Jackson County, Missouri, in 1833.
All of the conflicts in the Mormon War occurred in a corridor 100 miles (160 km) to the east and northeast of Kansas City, Missouri.
As a result of the war, nearly all Mormons in Missouri, estimated at more than ten thousand, were forced to leave the state. Most of these refugees settled in or near what would become the city of Nauvoo, Illinois.
Source: Wikipedia http://en.wikipedia.org/wiki/1838_Mormon_War