The Mougin turret is a land-based revolving gun turret that housed some of the heaviest armament in French fortifications of the late 19th and early 20th centuries. While not reliably resistant to the explosive shells of opposing artillery, Mougin turrets remained active through 1940, when they engaged German and Italian forces during the Battle of France and the Italian invasion of France. The turrets were used at twenty-two forts of the Séré de Rivières system built in the 1870s.