In early 1861, President Abraham Lincoln issued a call for the state of Missouri to enlist four regiments to fight against the Confederate States of America. However, then-Missouri governor Claiborne F. Jackson refused to call and prepared to use the Missouri State Guard to seize a United States government arsenal in St. Louis, Missouri. In response, Union general Nathaniel Lyon moved aggressively against the pro-Confederate Guard, driving the force away from St. Louis and removing Jackson from official government leadership. The Missouri State Guard, now commanded by Sterling Price, fell back towards the city of Springfield in southwestern Missouri, followed by Lyon and his Union army.