Missouri in the American Civil War

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During the American Civil War, Missouri was a hotly contested border state populated by both Union and Confederate sympathizers. It sent armies, generals, and supplies to both sides, maintained dual governments, and endured a bloody neighbor-against-neighbor intrastate war within the larger national war.

A slave state since statehood in 1821, Missouri's geographic position in the central region of the country and at the rural edge of the American frontier ensured that it remained a divisive battleground for competing Northern and Southern ideologies in the years preceding the war. When the war began in 1861, it became clear that control of the Mississippi River and the burgeoning economic hub of St. Louis would make Missouri a strategic territory in the Trans-Mississippi Theater.

By the end of the war in 1865, nearly 110,000 Missourians had served in the Union Army and at least 40,000 in the Confederate Army; many had also fought with bands of pro–Confederate partisans known as "bushwhackers".^[1][2][3] The war in Missouri was continuous between 1861 and 1865, with battles and skirmishes in all areas of the state, from the Iowa and Illinois borders in the northeast to the Arkansas border in the southeast and southwest. Counting minor actions and skirmishes, Missouri saw more than 1,200 distinct engagements within its boundaries; only Virginia and Tennessee exceeded this total.

The first major Civil War battle west of the Mississippi River took place on August 10, 1861, at Wilson's Creek, Missouri, while the largest battle west of the Mississippi River was the Battle of Westport in Kansas City in 1864.