[1] The Missouri General Assembly passed the "Military Bill" on May 11, 1861, in direct response to the Camp Jackson Affair in St. Louis the previous day.

This prohibition included the predominantly unionist German United States Reserve Corps regiments mustered in St. Louis in excess of the Missouri requirement under the Federal Militia Act of 1792.

It also specified that the language of all spoken commands was to be English,[2] a specification intended to exclude ethnic Germans, who were predominantly Unionist in their political orientation.

The next day Governor Jackson called for 50,000 volunteers to defend Missouri from the Union army; thousands of additional men answered the proclamation and enlisted in their respective districts/divisions.

Another victory on July 5 at the Battle of Carthage bought time for Price to begin training and organizing his raw recruits, many of whom had reported for military duty carrying only farm implements or antiquated hunting weapons.

A key figure in efforts to impose order on the embryonic organization was Adjutant General Lewis Henry Little, a native of Maryland and career Army officer.

A bold dash by Major Charles Zagonyi's mounted vanguard routed local MSG troops waiting in ambush on October 25, 1861, at the First Battle of Springfield.

A small number of Guard units remained independent until the end of the war in 1865, seeing action in several engagements in the Trans-Mississippi Theater under generals Mosby M. Parsons and James S. Rains.

The Guard's strength peaked at about 23,000 to 28,000 in September 1861 with about 5,000 in Southeast Missouri in M. Jeff Thompson's First Division operating independently of the main body surrounding Price near Lexington.