1st Missouri Volunteer Infantry ( 3 Months , 1861 ) The 1st Missouri Volunteers evolved from one of several unofficial pro - Unionist Home Guards militia formed in St . Louis in the early months of 1861 by Congressman Francis Preston Blair , Jr . and other Unionist activists . The militia that would become the First Missouri was largely composed of ethnic Germans , although Companies K and I had significant numbers of native born American citizens and Irish - Americans . Although initially without any official standing , beginning on April 22 , 1861 the four " underground " militia regiments Blair helped organize were sworn into Federal service at the St . Louis Arsenal by Captain John Schofield acting on the authority of President Lincoln . The 1st Missouri Volunteer Infantry elected Congressman Blair colonel of the regiment . The new Missouri Volunteer regiments , subsequently elected ( then ) Captain Nathaniel Lyon as the brigadier general of the new brigade of Missouri volunteers . President Lincoln would later confirm Lyon ' s promotion from Captain to Brigadier general . Military Service . On May 10 , 1861 the 1st Missouri under Colonel Blair participated in the arrest of the Missouri Volunteer Militia drilling at Camp Jackson at Lindell Grove on the western border of St . Louis City . As the Missouri militiamen were being march under guard back to the Arsenal near the riverfront , angry crowds confronted the Federal forces and the confused situation soon devolved into rioting and gunfire . Over 27 people were killed and the Camp Jackson Affair helped to polarize the state and send Missouri down the road to its own internal civil war . After the collapse of a truce negotiated by Federal Brigadier General William S . Harney and Missouri State Guard commander Sterling Price , the 1st Missouri , along with other Federal forces were ordered by Lyon to move on the Missouri state capitol , at Jefferson City . When the Federal forces arrived on June 15 , the pro - secessionist Governor , Claiborne Fox Jackson had already abandoned the city and Brigadier General Lyon ' s forces captured the city without resistance . Lyon then pursued Jackson and the State Guard to nearby Boonville where the 1st Missouri Volunteers helped defeat the newly organized Missouri State Guard on June 17 in the short , one - sided Battle of Boonville . While the Battle of Boonville was small by later war standards , it had major strategic consequences , driving the pro - secessionist forces into the southern part of the state and securing the Missouri River valley and communications across the state for the Federal government . The 1st Missouri continued to campaign with Lyon , marching southwest to Springfield , eventually confronting a united Confederate and Missouri State Guard force near Springfield . The resulting Battle of Wilson ' s Creek fought ten miles south of the city on August 10 , 1861 was a bloody affair , and the second costliest in American History up to that time . The 1st Missouri , now under Lieutenant Colonel Charles Andrews , fought with Lyon ' s detachment of the Federal force on Bloody Hill . Isolated and outnumbered after a second Federal element under Colonel Franz Sigel was routed , the Federals on Bloody hill fought the Confederate forces to a stalemate . The battle ended only after General Lyon was killed leading the 1st Iowa Infantry against the Confederate right . As the senior U . S . Army regular officer present , command devolved to Major Samuel D . Sturgis . Concerned about his force ' s ammunition supply , Sturgis decided to withdraw towards Springfield . The 1st Missouri withdrew to Springfield and then to Rolla . A significant portion of the units members reenlisted as three - year volunteers , retaining the designation as the 1st Missouri Infantry . The regiment was then converted into an artillery unit by order of Major General John C . Fremont , Commander of the Department of the West . The resulting 1st Missouri Light Artillery would see action in most of the campaigns in the Western Theater .