Chetniks in World War I

Chetniks (World War I)
Active	August 1914 – November 18
Allegiance	Kingdom of Serbia
Branch	Royal Serbian Army
Type	Irregular infantry
Size	2,250 (August 1914)
Part of	In 1914: Third Army, Užice Army
Engagements	First World War

Chetniks in World War I were members of auxiliary units used by the Royal Serbian Army for special operations against invading Austro-Hungarian, Bulgarian and German forces.

First organised into military formations during the Balkan Wars (1912–1913), they became an integral part of the Royal Serbian Army in August 1914 with the formation of four detachments. Their primary task was to defend the borders before transitioning to operate as special forces behind enemy lines, disrupting operations and conducting diversionary tactics.

The Chetniks were engaged in action from the onset of the conflict, enduring heavy casualties in direct combat, estimated at 60% during the first Serbian Campaign. With the occupation of the country, they evolved into resistance fighters, forming new units and conducting guerrilla warfare, ultimately playing a significant role in the liberation of Serbia and Montenegro. The Serbian army was one of the first in Europe to have such guerrilla detachments in its ranks. After the war, Chetnik detachments were disbanded.