Freikorps (pronounced [ˈfʀaɪ̯ˌkoːɐ̯], "Free Corps") were German volunteer units that existed from the 18th to the early 20th centuries, the members of which effectively fought as mercenaries, regardless of their own nationality. In German-speaking countries, the first so-called Freikorps ("free regiments", German: Freie Regimenter) were formed in the 18th century from native volunteers, enemy renegades and deserters, and criminals. These sometimes exotically equipped units served as infantry and cavalry (or more rarely as artillery), sometimes in just company strength, sometimes in formations up to several thousand strong; there were also various mixed formations or legions. The Prussian von Kleist Freikorps included infantry, jäger, dragoons and hussars. The French Volontaires de Saxe combined uhlans and dragoons.
In the aftermath of World War I and during the German Revolution of 1918–19, Freikorps consisting largely of World War I veterans were raised as right-wing paramilitary militias, ostensibly to fight on behalf of the government against the Soviet-backed German Communists attempting to overthrow the Weimar Republic. However, the Freikorps also despised the Republic and were involved in assassinations of its supporters. The Freikorps were widely seen as the precursor to Nazism, and many of their volunteers ended up joining the Nazi militia, the Sturmabteilung (SA). An entire series of Freikorps awards also existed.