In the Middle Ages Bouillon was a lordship within the Duchy of Lower Lorraine and the principal seat of the Ardennes-Bouillon dynasty in the 10th and 11th century. In the 11th century they dominated the area, and held the ducal title along with many other titles in the region. Bouillon was the location of the ducal mint and the dominant urban concentration in the dukes' possession.
There is a common misconception that Bouillon was a County. While the lords of Bouillon often were counts and dukes, Bouillon itself was not a county. The fortification of Bouillon Castle was, along with the County of Verdun, the core of the possessions of the Ardennes-Bouillon dynasty, and their combined territory was a complex mixture of fiefs, allodial land and other hereditary rights throughout the area. An example of the latter is the Advocacy of the monastery of Saint-Hubert en Ardennes, which was granted to Godfrey II by the Bishop of Li�ge.
The most famous of the Lords of Bouillon was Godfrey of Bouillon, a leader of the First Crusade and the first ruler of the Kingdom of Jerusalem. He sold Bouillon Castle to the Bishopric of Li�ge. The bishops started to call themselves dukes of Bouillon, and the town emerged as the capital of a sovereign duchy by 1678, when it was captured from the bishopric by the French army and given to the La Tour d'Auvergne family. The duchy was prized for its strategic location as "the key to the Ardennes" (as Vauban called it) and hence to France itself. It remained a quasi-independent protectorate, like Orange and Monaco, until 1795, when the Republican Army finally annexed it to France
