A gendarmerie is a military force with law enforcement duties among the civilian population. The term gendarme is derived from the medieval French expression gens d'armes, which translates to "men-at-arms". In France and some Francophone nations, the gendarmerie is a branch of the armed forces that is responsible for internal security in parts of the territory, with additional duties as military police for the armed forces. It was introduced to several other Western European countries during the Napoleonic conquests. In the mid-twentieth century, a number of former French mandates and colonial possessions adopted a gendarmerie after independence. A similar concept exists in Eastern Europe in the form of internal troops, which are present in many countries of the former Soviet Union and its former allied countries.