BOUILLON, formerly the seat of a dukedom in the Ardennes, now a small town in the Belgian province of Luxemburg. Pop. (1904) 2721. It is most picturesquely situated in the valley under the rocky ridge on which are still the very well preserved remains of the castle of Godfrey of Bouillon (q.v.), the leader of the first crusade. The town, 690 ft. above the sea, but lying in a basin, skirts both banks of the river Semois which is crossed by two bridges. The stream forms a loop round and almost encircles the castle, from which there are beautiful views of the sinuous valley and the opposite well-wooded heights. The whole effect of the grim castle, the silvery stream and the verdant woods makes one of the most striking scenes in Belgium. In the 8th and 9th centuries Bouillon was one of the castles of the counts of Ardenne and Bouillon. In the 10th and 11th centuries the family took the higher titles of dukes of Lower Lorraine and Bouillon. These dukes all bore the name of Godfrey (Godefroy) and the fifth of them was the great crusader. He was the son of Eustace, count of Boulogne, which has led many commentators into the error of saying that Godfrey of Bouillon was born at the French port, whereas he was really born in the castle of Baisy near Genappe and Waterloo. His mother was Ida d’Ardenne, sister of the fourth Godfrey (“the Hunchback”), and the successful defence of the castle when a mere youth of seventeen on her behalf was the first feat of arms of the future conqueror of Jerusalem. This medieval fortress, strong by art as well as position before the invention of modern artillery, has since undergone numerous sieges. In order to undertake the crusade Godfrey sold the castle of Bouillon to the prince bishop of Liége, and the title of duke of Bouillon remained the appendage of the bishopric till 1678, or for 580 years. The bishops appointed “châtelains,” one of whom was the celebrated “Wild Boar of the Ardennes,” William de la Marck. His descendants made themselves quasi-independent and called themselves princes of Sedan and dukes of Bouillon, and they were even recognized by the king of France. The possession of Bouillon thenceforward became a constant cause of strife until in 1678 Louis XIV. garrisoned it under the treaty of Nijmwegen. From 1594 to 1641 the duchy remained vested in the French family of La Tour d’Auvergne, one of whom (Henry, viscount of Turenne and marshal of France) had married in 1591 Charlotte de la Marck, the last of her race. In 1676 the duke of Créquy seized it in the name of Louis XIV., who in 1678 gave it to Godefroy Marie de La Tour d’Auvergne, whose descendants continued in possession till 1795. Bouillon remained French till 1814, and Vauban called it “the key of the Ardennes.” In 1760 the elder Rousseau established here the famous press of the Encyclopaedists. In 1814–1815, before the decrees of the Vienna Congress were known, an extraordinary attempt was made by Philippe d’Auvergne of the British navy, the cousin and adopted son of the last duke, to revive the ancient duchy of Bouillon. The people of Bouillon freely recognized him, and Louis XVIII. was well pleased with the arrangement, but the congress assigned Bouillon to the Netherlands. Napoleon III. on his way to Germany after Sedan slept one night in the little town, which is a convenient centre for visiting that battlefield.