AREMBERG, or ARENBERG  , formerly a German duchy of the Holy Roman Empire in the circle of the Rhine Palatinate, between Jtilich and Cologne, and now belonging to the Prussian administrative district of Coblenz . The hamlet of Aremberg is at the foot of a basalt hill 2067 ft. high, on the summit of which are the ruins of the castle which was the original seat of the family of Aremberg . The lords of Aremberg first appear early in the 12th century, but had died out in the male line by 1279 . From the marriage of the heiress Mathilda (1282–1299) with Engelbert II., count of La Marck (d . 1328), sprang two sons . The elder of these, Adolf II, (d . 1347), inherited the countship of La Marck; the second, Engelbert III . (d . 1387), the lordship of Aremberg, which he increased by his marriage with Marie de Looz, heiress of Lumain . The lordship of Aremberg remained in his family till 1547, when it passed, by his marriage with Margaret, sister of the childless Robert III., to John of Barbancon, of the great house of Ligne, who assumed the name and arms of Aremberg, and was created a count of the Empire by Charles V . He was governor of Friesland, and for a while commanded the Spanish and Catholic forces against the " beggars," falling at the battle of Heiligerlee in 1568 . His son Charles (d .

1618) greatly in-creased the possessions of the house by his marriage with

Ann of Croy, heiress of Croy and of Chimay-Aerschot, and in 1576 was made prince of the Empire by Maximilian II . His grandson, Philip Francis, was made duke in 1644 by the emperor Ferdinand III., and was succeeded by his brother Charles Eugene (d . 1681), who married Marie Henriette de Vergy de Cusance, heiress of Perwez (d . 1700) . Their son, Duke Philip Charles Francis, was killed in 1691 fighting against the Turks, and was succeeded by Leopold (1754), a distinguished soldier of the War of the Spanish Succession, and patron of Rousseau and Voltaire . His son Charles (d . 1778) was an Austrian field-marshal during the Seven Years' War, and married Louise Margaret of La Marck-Lumain, heiress of the countship of Schleiden and lordship of Saffenberg . By the peace of Luneville (February 1801), the next duke, Louis Engelbert, lost the greater part of his ancestral domain, but received in compensation Meppen and Recklinghausen . On the establishment of the con-federation of the Rhine, his son Prosper Louis (to whom, becoming blind, he had ceded his domains in 1803) became a member (18o6), and showed great devotion to the interests of France; but in 1810 he Jost his sovereignty, Napoleon incorporating Meppen with France and Recklinghausen with the grand-duchy of Berg, and indemnifying him by a rent of 240,702 francs . In 1815 he received back his possessions, which were mediatized by the congress of Vienna, Recklinghausen falling to Prussia and Meppen to Hanover . On account of the one portion he became a peer of the Westphalian estates, and by the other a member of the upper house in Hanover . George IV. of England (9th May 1826) elevated the duke's Hanoverian possessions to a dukedom under the title of Aremberg Meppen .

His brother Auguste

Raymond, Comte de la Marck (1753-1833), became famous during the early stages of the French Revolution for his friendship with Mirabeau (q.v.) . Duke Prosper Louis died in 1861, and was succeeded by his son Engelbert (d . 1875), who was followed in his turn by his son Engelbert (b . 1872) . The duke of Aremberg is one of the wealthiest of the great continental nobles . His feudal domain in Germany covers an area of over 1too sq. m., besides which he has large estates in Belgium and France . The duke has residences in Brussels, where he has a famous collection of pictures, and at the chateau of Klemenswerth near Meppen .