Although the name “Red Legs” is commonly conflated with the term “jayhawkers” to describe Kansas guerilla units that fought for the Free-State side during the Bleeding Kansas era or the Union side in the Civil War, Red Legs originally referred to a specific paramilitary outfit that organized in Kansas at the height of the Civil War.

Free-Soil settlers in Kansas created the Topeka Constitution and elected their own legislature to manifest the democratic ideals of popular sovereignty and bring their struggle against proslavery forces in Kansas Territory to a national audience. When the ballot box failed to solve the dispute, settlers turned to bullets to settle their differences, and the violence over slavery in the territory brought “Bleeding Kansas” to national attention.

Before the start of the Civil War, the name “jayhawkers” applied to bands of robbers, associated with the Kansas Free-Stater cause, who rustled livestock and stole property on both sides of the state line. During this period, a jayhawker could be a hero or a villain, depending on individual circumstances or one’s opinion on the issue of slavery in Kansas Territory. By the time the war ended, however, the term “jayhawkers” became synonymous with Union troops led by abolitionists from Kansas, and "jayhawking" became the generic term for armies plundering and looting from civilian populations nationwide.