After the outbreak of the
American Civil War in April 1861,
Missouri was considered to be a
border state, as
slavery was legal within the state, but it did not vote to
secede.
Governor of Missouri Claiborne F. Jackson supported the
Confederate States of America, and began to use
militia to support the Confederate cause in Missouri by marching towards the
arsenal in
St. Louis.
Brigadier General Nathaniel Lyon, commander of the Union forces in St. Louis, acted quickly and forced Jackson's militia to surrender in the
Camp Jackson affair. After the debacle at Camp Jackson, Jackson formed a new organization named the
Missouri State Guard and appointed
Sterling Price to command it. Lyon moved to confront Price's new force, defeating it at the
Battle of Boonville. Price and the Missouri State Guard retreated to the vicinity of
Springfield in southwestern Missouri, where it was joined by a
Confederate States Army force commanded by Brigadier General
Benjamin McCulloch. On August 10, Lyon decided to attack the combined forces of Price and McCulloch while they were encamped along
Wilsons Creek, despite being outnumbered by the Confederates and Missourians by a factor of over two-to-one. In the ensuing
Battle of Wilson's Creek, the Union forces were defeated and Lyon was killed. After Wilson's Creek, the Union army retreated to
Rolla, Missouri. McCulloch and his forces withdrew to
Arkansas, and Price's Missouri State Guard occupied Springfield.
John C. Fremont arrived to take control of Union forces in the state, and
James H. Lane took command of several
Kansas regiments stationed at
Fort Scott. Meanwhile, Price began to advance north with a force estimated to number at either 6,000 or 10,000 men. In response to Price's incursion, Fremont declared Missouri to be subject to
martial law. ==Battle==