BERG (Ducatus Montensis), a former duchy of Germany, on the right bank of the Rhine, bounded on the north by the duchy of Cleves, on the east by the countship of La Marck and the duchy of Westphalia, and south and west by the bishopric of Cologne. Its area was about I,I2osq.m. The district was raised in IIo8 to the rank of a countship, but did not become a duchy till 138o, after it had passed into the possession of the Jiilich family. In 2423 the duchy of Jiilich fell to Adolf of Berg, and in 1437 the countship of Ravensberg was united to the duchies. The male line of the dukes of Jiilich-Berg-Ravensberg became ex tinct in 1511, and the duchy passed by marriage to John III. (d. , duke of Cleves and count of La Marck, whose male line became extinct with the death of John William, bishop of Mun ster, in 1609. The question of succession led to a prolonged contest, which was one of the causes of the Thirty Years' War. It was settled in 1614 by a partition.
Berg was bestowed by Napoleon on Joachim Murat, who bore the title of grand-duke of Berg. The Congress of Vienna awarded it to Prussia.