The term "partisan" was used in the 17th century to describe the leader of a war party. In 12th century Europe, war parties, or detachments, were frequently used on raids to gather or destroy supplies. Techniques of partisan warfare were described in detail in Johann von Ewald's Abhandlung über den kleinen Krieg (1789).
The initial concept of partisan warfare was the use of troops raised from the local population in a war zone, or in some cases regular forces, that would operate behind enemy lines to disrupt communications, seize posts or villages as forward operating bases, ambush convoys, impose war taxes or contributions, raid logistical stockpiles, and compel enemy forces to disperse and protect their base of operations. It was this concept of partisan warfare that would later form the basis of the "partisan rangers" of the American Civil War. In that conflict, Confederate partisan leaders, such as John S. Mosby, operated along the lines described by Von Ewald (and later by both Jomini and Clausewitz). In essence, 19th century American partisans were closer to Commando or Ranger forces raised during World War II than the "partisan" forces operating in occupied Europe. Such fighters would have been legally considered uniformed members of their country's armed forces.
Partisans in the mid-19th century were substantially different from raiding cavalry, or from unorganized/semi-organized guerrilla forces. The Russian partisans played a crucial part in the downfall of Napoleon. Their fierce resistance and persistent inroads helped compel the French emperor to flee Russia in 1812.
It was during World War II that the current definition of "partisan" became the dominant one—focusing on irregular forces in opposition to an attacking or occupying power. Soviet partisans, especially those active in Belarus, were able to effectively harass German troops and significantly hamper their operations in the region. As a result, Soviet authority was re-established deep inside the German held territories. There were even partisan kolkhozes that were raising crops and livestock to produce food for the partisans. The communist Yugoslav partisans were a leading force in the liberation of their country during the People's Liberation War of Yugoslavia.