Bouillon, a town of Belgian Luxemburg, on the Semoy, 17 m. W. S. W. of Neufchateau; pop. in 1866, 2,765. It has an ancient castle, and was formerly the capital of the lordship of Bouillon (which had been separated by partition from the county of Boulogne), a district in the Ardennes containing several large villages and about 20,000 inhabitants. This district was mortgaged by Godfrey the crusader, in 1095, to the bishop of Liege, whose successors held it till 1482, when it was taken by Guillaume de La Marck, prince of Sedan. Restored to the bishop by Charles V. in 1529, it was again taken in 1548 by Robert de La Marck, whose descendants were dukes of Bouillon, which title afterward passed by marriage into the family of La Tour d'Auvergne, viscounts of Turenne. Bouillon was held by the French from 1676 to 1815. The title of prince of Bouillon was assumed in 1792 by Philip d'Auvergne, a captain in the British navy, and was borne by him until his death in 1816, when the contest between different claimants was set at rest by a decision (July 1) in favor of the French prince Charles Alain de Rohan-Guemene, whose posterity still bear the title.

Bouillon has belonged to Belgium since 1831.

Bouillon.