A partisan is a member of a domestic irregular military force formed to oppose control of an area by a foreign power or by an army of occupation through some form of insurgent activity.
Simone Segouin, a French partisan credited with capturing 25 German soldiers in the Chartres area, poses with an MP 40 submachine gun, 23 August 1944
Civilians being shot at in Kondomari, 1941
EAM/ELAS partisans in 1944
Rescue of Allied airmen by Yugoslav Partisans, Otočac 1943
Irregular military is any military component distinct from a country's regular armed forces, representing non-standard militant elements outside of conventional governmental backing. Irregular element
Chouans hiding behind a dolmen
British SAS patrol in armed jeeps during the North African campaign of World War II
A group of Ottoman bashi-bazouks in Bulgaria, irregular soldiers of the military of the Ottoman Empire, 1877–1878
Gardner's Irregular Horse of Hindustani Mahomedans