A gendarmerie or gendarmery (Template:Pron-en or /ˌʒɑːndɑrməˈriː/) is a military body charged with police duties among civilian populations. The members of such a body are called gendarmes. The term maréchaussée (or marshalcy) may also be used (e.g., Royal Marechaussee) but is now uncommon.

The word gendarme comes from Old French gens d'armes, meaning men-at-arms. Historically, during the Late Medieval to the Early Modern period, the term referred to a heavily armoured cavalryman of noble birth, primarily serving in the French army (see Gendarme (historical)). The word gained policing connotations after the French Revolution when the Maréchaussée of the Ancien Régime was renamed the Gendarmerie.

In the United Kingdom, there is a body called Her Majesty's Bodyguard of the Honourable Corps of Gentlemen at Arms. Gentlemen at Arms is a near etymological equivalent to the term gendarme. This body is, however, purely ceremonial and is not considered a gendarmerie.

Historically the spelling in English is gendarmery, but the French spelling gendarmerie is now more common. The Oxford English Dictionary (OED) still uses gendarmery as the principal spelling while Merriam-Webster uses gendarmerie as the principal spelling.

The English word constabulary (also derived from French) has been used in a British colonial context for centralized armed police services, such as the Royal Irish Constabulary, Royal Ulster Constabulary, Royal Newfoundland Constabulary and Jamaica Constabulary Force.

These forces are normally titled “gendarmerie”, but gendarmeries may bear other titles, for instance the Carabinieri in Italy, the Guarda Nacional Republicana in Portugal or the Guardia Civil in Spain.

Forces which are no longer considered military retain the title “gendarmerie” for reasons of tradition. For instance, the French language title of the Royal Canadian Mounted Police is Gendarmerie royale du Canada (GRC) (i.e., Royal Gendarmerie of Canada) because it was traditionally a military force (although separate from the Canadian Army) and because until the 1960s it retained an honorific status as a regiment of dragoons. The Argentine Gendarmerie is a military force (in terms of training, identity and public perception, and it was involved in combat in the Falklands War), but for legal purposes is a "security force", not an "armed force", because this is necessary under Argentine law in order to allow jurisdiction over the civilian population.

Since every country uses institutional terms such as “gendarmerie” as it wishes, there are cases in which the term may become confusing. For instance, in the French speaking Cantons of Switzerland the “gendarmeries” are the uniformed civil police. In Chile, confusingly, the word “gendarmerie” can for historic reasons be used to refer to the prison service, while as previously mentioned the actual gendarmerie force is called the "carabineros".

As a result of their duties within the civilian population, gendarmeries are sometimes described as "para-military" rather than "military" forces (essentially in the English-speaking world where policing is rarely associated with military forces) although this description rarely corresponds to their official status and capabilities. Gendarmes are often deployed in military situations, sometimes in their own country, and often in humanitarian deployments abroad.

A gendarmerie may come under the authority of a ministry of defence (e.g., Italy) or a ministry of the interior (e.g., Argentina and Romania), or even both at once (e.g., India, Chile, France, and Portugal). Generally there is some coordination between a ministry of defence and a ministry of the interior over the use of gendarmes.

Gendarmeries are police services, but in many countries (e.g., France) the word "police" normally implies civilian police. Gendarmeries are military police, however the term "military police" can be misleading, since in English it carries strong implications of policing within the military ("provost" policing), which is not the basic purpose of a gendarmerie (although in many countries - e.g., Italy - it is a task which gendarmes carry out). In countries where the gendarmerie and civilian police co-exist there may be rivalries and tensions between the forces. This was one of the reasons cited for the decision to disband the Belgian Gendarmerie, absorbing its functions into those of a new national police force.

In some cases, a police service's military links are ambiguous and it can be unclear whether a force should be defined as a gendarmerie or not, (e.g., Canada's RCMP, Mexico's Policia Federal, Brazilian Polícia Militar, or the former South African Police until 1994). Services such as the Italian Guardia di Finanza would not normally be defined as a gendarmerie (but at times might be) since the service is both of ambiguous military status and does not have general policing duties in the civilian population. In Russia, the Interior Troops are military units with quasi-police duties.

In comparison to civilian police forces, gendarmeries may provide a more disciplined force whose military capabilities (e.g., armored group in France with armored personnel carriers) make them more capable of dealing with armed groups and with all types of violence (e.g., India's Rapid Action Force specializes in riot control and counter-terrorism). On the other hand, the necessity of a more stringent selection process for military service, especially in terms of physical prowess and health, restricts the pool of potential recruits in comparison to those a civilian police force could select from.

Gendarmeries may also provide various military or police services. For instance in France, the gendarmerie is in charge of crowd and riot control (Gendarmerie Mobile, along with some corresponding units in the civilian police), counter-terrorism and hostage rescue (GIGN, again along with some corresponding units in the civilian police), maritime surveillance, police at sea and coast guard (Gendarmerie maritime), control and security at airports and air traffic police (Gendarmerie des transports aériens), official buildings guard, honorary services and protection of the President (Garde Républicaine), mountain rescue (Peloton de Gendarmerie de Haute Montagne) and security of nuclear weapons sites.

The use of military organisations to police civilian populations is common to many time periods and cultures. Although it cannot be considered a French concept, the French gendarmerie has been the most influential model of such an organisation.

Many countries that were once under French influence have a gendarmerie. For instance, Belgium, Luxembourg and Austria had gendarmeries through Napoleonic influence, but all these gendarmeries, have merged with the civil police, in 2001, 2002 and 2005 respectively. Many former French colonies, especially in Africa, also have gendarmeries.

A common gendarmerie symbol is a flaming grenade, which was first used as a gendarmerie symbol by the French.

Gendarmes play an important role re-establishing law and order in conflict areas, a task which is suited to their purpose, training and capabilities^{[citation needed]}. Gendarmeries are widely used in peacekeeping operations, for instance in the former Yugoslavia^{[citation needed]}.

• List of Gendarmerie
• Military Aid to the Civil Power
• Paramilitary
• Military police
• Police
• Field Force
• National Guard
• Posse Comitatus Act
• Constabulary
• People's Armed Police
• Association of the European and Mediterranean Police Forces and Gendarmeries with Military Status