Military organization of citizens with limited military training who are available for emergency service, usually for local defense. In many countries the militia is of ancient origin. The Anglo-Saxons required every able-bodied free male to serve. In colonial America it was the only defense against hostile Indians when regular British forces were not available. In the American Revolution the militia, called the Minutemen, provided the bulk of the American forces. Militias played a similar role in the War of 1812 and the American Civil War. State-controlled volunteer militias in the U.S. became the National Guard. British militia units, begun in the 16th century for home defense and answerable to the county sheriff or lord lieutenant, were absorbed into the regular army in the 20th century. Today various paramilitary organizations, from U.S. white supremacists to revolutionaries in the developing world, use the term militia to accentuate their populist origins.
Learn more about militia with a free trial on Britannica.com.