Missouri State Militia (Union)

The Missouri State Militia was a federally funded state militia organization of Missouri conceived in 1861 and beginning service in 1862 during the American Civil War. It was a full-time force whose primary purpose was to conduct offensive operations against Confederate guerrillas and recruiters as well as oppose raids by regular Confederate forces. The MSM at one time numbered more than 13,000 soldiers, but this force was reduced to 10,000 soldiers, by the United States government.

Original Missouri state militia (pre-Missouri State Guard)
Prior to the Civil War, Missouri had a system of state-regulated local militia companies organized as the official Missouri Volunteer Militia (MVM), that could be called up by the governor for emergencies or annual drill. During the secession crisis Missouri Governor Claiborne Jackson used the MVM covertly as secessionist tool until the majority of its members in eastern Missouri, and almost all the state's arms, were captured during the Camp Jackson Affair in St. Louis. The events in St. Louis prompted the Missouri legislature to pass Governor Jackson's "Military Bill" reorganizing the state militia into the Missouri State Guard.

Home Guard
In Missouri at the beginning of the Civil War, volunteer Unionist Home Guard regiments were formed with the support of Federal authorities to oppose secessionist Governor Claiborne Jackson's efforts at organizing secessionist strength, and his efforts to prevent Missouri enlistments into Federal service. Brigadier General Nathaniel Lyon was given authority by the War Department to organize the Home Guard units throughout Missouri on June 11, 1861.

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