The Freischar (German: [ˈfʁaɪ̯ˌʃaːɐ̯] ) was the German name given to an irregular, volunteer military unit that, unlike regular or reserve military forces, participated in a war without the formal authorisation of one of the belligerents, but on the instigation of a political party or an individual. A Freischar deployed against a foreign enemy was often called a Freikorps. The term Freischar has been commonly used in German-speaking Europe since 1848. The members of a Freischar were called Freischärler (German: [ˈfʁaɪ̯ˌʃɛːɐ̯lɐ] ). As early as 1785 Johann von Ewald published in Kassel his Essay on Partisan Warfare (German: Abhandlung über den kleinen Krieg), which described his experiences with the rebels in the North American colonies.