A militia / is generally an army or some other fighting organization of non-professional soldiers, citizens of a nation, or subjects of a state, who can be called upon for military service during a time of need, as opposed to a professional force of regular, full-time military personnel, or historically, members of a warrior nobility class (e.g., knights or samurai). Generally unable to hold ground against regular forces, it is common for militias to be used for aiding regular troops by skirmishing, holding fortifications, or irregular warfare, instead of being used in offensive campaigns by themselves. Militia are often limited by local civilian laws to serve only in their home region, and to serve only for a limited time; this further reduces their use in long military campaigns.
With the emergence of professional forces (in the form of mercenaries whose livelihood was military service) during the Renaissance, Western European militias wilted; later however, they would be revived as part of Florentine civic humanism, which held that professional militaries were a result of corruption, and admired the Roman model. The civic humanist ideal of the militia was spread through Europe by the writings of Niccolò Machiavelli (According to Hörnqvist, The Prince, ch. 12 and 13, Discourses on Livy, and The Art of War.)
Beginning in the late 20th century, some militias (in particular officially recognized and sanctioned militias of a government) act as professional forces, while still being "part-time" or "on-call" organizations. For instance, the members of some U.S. Army National Guard units are considered professional soldiers, as they are trained to maintain the same standards as their "full-time" (active duty) counterparts.
Militias thus can be military or paramilitary, depending on the instance. Some of the contexts in which the term "militia" is used include:
- Forces engaged in defense activity or service, to protect a community, its territory, property, and laws.
- The entire able-bodied population of a community, town, county, or state, available to be called to arms.
- A subset of these who may be legally penalized for failing to respond to a call-up.
- A subset of these who actually respond to a call-up, regardless of legal obligation.
- A private, non-government force, not necessarily directly supported or sanctioned by its government.
- An irregular armed force enabling its leader to exercise military, economic, and political control over a subnational territory within a sovereign state (See: Warlord).
- An official reserve army, composed of citizen soldiers. Called by various names in different countries, such as the Army Reserve, National Guard, or state defense forces.
- The national police forces in several former communist states such as the Soviet Union and the Warsaw Pact countries, but also in the non-aligned SFR Yugoslavia. The term was inherited in Russia and other former CIS countries, where they are known as militsiya.
- In France the equivalent term "Milice" has become tainted due to its use by notorious collaborators with Nazi Germany.
- A select militia is composed of a small, non-representative portion of the population, often politicized.