Bouillon the one from Godfrey

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 Liège. 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.