A former state of W Germany bordering The Netherlands with Cleves as its capital. A county from late Carolingian times, it was made a duchy in 1417. John III, Duke of Cleves, gained other duchies through marriage (1521) and his daughter, Anne of Cleves, married Henry VIII of England (1540). In 1609 the male line became extinct and a lengthy quarell over succession followed which was not settled until 1666 by the Treaty of Cleves. By then Cleves has been acquired by Brandenburg (1614). It was held by France during the French Revolutionary Wars and returned to Prussia in 1815.