St. Louis in the American Civil War
St. Louis, Missouri was a strategic location during the American Civil War, an important city to the Union army and navy. It was a major supply depot and launching point for campaigns in the Western Theater.
German Americans 
Located near the junction of the Missouri River, the Illinois River and the Mississippi River, St. Louis was a major port and commercial center with a growing industrial base. The population reached 160,000 in 1860 and consisted mostly of Catholic German Americans and Irish Americans. The early Union volunteer regiments in St. Louis were mostly made up of the dominant German immigrants.
St. Louis Arsenal 
In March 1861, Captain Nathaniel Lyon arrived in St. Louis in command of Company B of the 2nd U.S. Infantry. At the time the state of Missouri was relatively neutral in the dispute between North and South, but Missouri Governor Claiborne F. Jackson was a strong Southern sympathizer. Lyon was concerned that Jackson meant to seize the federal arsenal in St. Louis if the state seceded and that the Union had insufficient defensive forces to prevent the seizure. He attempted to strengthen the defenses, but came into opposition from his superiors, including Brig. Gen. William S. Harney of the Department of the West. Lyon employed his friendship with Francis P. Blair, Jr., to have himself named commander of the arsenal. When the Civil War broke out and President Abraham Lincoln called for troops to put down the Confederacy, Missouri was asked to supply four regiments. Governor Jackson refused the request and ordered the Missouri militia to muster outside St. Louis under the stated purpose of training for home defense.
Lyon allegedly disguised himself as a farm woman to spy on the militia camp and confirmed the presence of artillery stolen from a Federal arsenal. Lyon himself had been extensively involved in the St. Louis Wide Awakes, a pro-Union paramilitary organization that he intended to arm from the arsenal and muster into the ranks of the federal army. Upon obtaining command of the arsenal, Lyon armed the Wide Awake units under guise of night. Lyon had most of the weapons in the arsenal secretly moved to Illinois and on May 10 he led the 2nd U.S. Infantry to the camp, forcing its surrender. Riots broke out in St. Louis after Lyon marched his prisoners through the city. The event provoked the Camp Jackson Affair of May 10, 1861, in which Lyons' troops opened fire on a crowd of civilians injuring at least 90 and killing 28. The Camp Jackson Affair polarized the population of Missouri, leading many once-neutral citizens to advocate secession and setting the stage for sustained violence between the opposing factions.
Civil War 
During the Civil War, St. Louis stayed under Union control because of the strong military base, and the public support from loyal Germans. The largest percentage of volunteers served in the Union army; some went south to fight for the Confederacy. Some people who stayed in the city during the war and supported the South smuggled supplies, medicine, and otherwise assisted Confederate soldiers.
No major battles were fought in or near the city, but the Mississippi River was a vital highway during the war. Divided loyalties to the Union and Confederacy caused rifts in some families in St. Louis.
Thousands of black refugees poured into St. Louis, where the Freedmen's Relief Society, the Ladies Union Aid Society, the Western Sanitary Commission, and the American Missionary Association (AMA) set up schools for their children.
St. Louis Riot 
The division of loyalties between Union and Confederacy did result in loss of life on May 11, 1861. Union soldiers, the Fifth Regiment, United States Reserve Corps, Missouri Volunteers was attacked by a mob of Confederate sympathizers within hours of it being mustered into service. The regiment was marching from the Arsenal when the mob attacked it on the corner of Walnut and Broadway. Shots were exchanged and six persons were killed. The Fifth Regiment consisted primarily of loyal Germans, having been recruited primarily from men of the Tenth Ward of St. Louis.
- Lawrence O. Christensen, "Black Education in Civil War St. Louis," Missouri Historical Review, April 2001, Vol. 95 Issue 3, pp 302-316
- William E. Parrish. A History of Missouri: Volume III, 1860 to 1875 (2001) ISBN 0-8262-0148-2
- R. Rombauer. The Union Cause in St. Louis in 1861 (1909)
- Annual Report of the Adjutant General of Missouri, For the Year ending December 31, 1865 Office of the Attorney General (1866) p. 79