American Civil War: During Price's Missouri Expedition, Union troops defeated Sterling Price's Confederate army in three successive battles: Marais des Cygnes, Mine Creek, and Marmiton River.

The American Civil War was a civil war in the United States between the Union and the Confederacy, which formed in 1861 by Southern states that had decided to secede from the Union to preserve slavery in the United States. The South saw slavery as threatened because of the election of Abraham Lincoln as president in 1860 and the growing abolitionist movement in the North. The war ended with a Union victory, dissolution of the Confederate States and the national abolition of slavery, freeing four million African Americans.