Guerrilla warfare was waged during the American Civil War (1861–1865) by both sides of the conflict, but most notoriously by the Confederacy. It gathered in intensity as the war dragged.

Marcellus Jerome Clarke was a Confederate captain who in 1864 became one of Kentucky's most famous guerrillas. He was rumored to be "Sue Mundy", a character publicized by George Prentice, editor of the Louisville Journal.