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.
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 Prince-Bishopric of Liège. The prince-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 prince-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 annexed it to France.
1065 - Godfrey the Bearded comes to terms with the emperor and rebuilds the castle in Bouillon.
1082 - Bouillon Castle is inherited by Godfrey of Bouillon, who sells it to the prince-bishop of Liège for 3 marks of gold and 1300 marks of silver in order to finance his participation in the First Crusade. Pursuant to the treaty, Godfrey and his three successors retain the right to repurchase the castle at the same price but have no money to make good this privilege.
1129 - Godfrey's indirect successor, Count Renaud of Bar, captures Bouillon Castle by force.
1141 - The prince-bishop of Liège expels Count Renaud from Bouillon.
May 21, 1484 - Treaty is signed at Tongeren, whereby the van der Marck family forfeits its claims to the prince-bishopric and supports Liège's struggle against Emperor Maximilian for the reward of 30,000 livres. Bouillon Castle is mortgaged to William van der Marck until the time of repayment.
1492 - The treaty of Donchery reiterates the provisions of the treaty of Tongeren. As no repayment follows, the van der Marck family retains Bouillon Castle and assumes the title of the Dukes of Bouillon.
1521 - The army of Emperor Charles V takes hold of Bouillon and restitutes it to the prince-bishopric of Liège.
1526 - Robert III van der Marck is promoted to Marshal of France and styles himself Duke of Bouillon on this occasion.
1552 - Henry II of France reconquers Bouillon from the prince-bishops and gives it to Robert IV.
1559 - The Treaty of Cateau-Cambresis restitutes Bouillon to the prince-bishops of Liège, stipulating that the rights to the disputed territory are to be determined by a special arbitration, which never takes place.
1598 - The Treaty of Vervins again calls for arbitration of the dispute between the prince-bishopric and the van der Marck family.
October 15, 1591 - Upon extinction of the van der Marck family, their heiress Charlotte is married to Henri de La Tour d'Auvergne, Marshal of France.
May 8, 1594 - Charlotte van der Marck dies without issue, and her claims to Bouillon pass to her husband, Henri de la Tour d'Auvergne.
October 24, 1594 - Charlotte's cousin, Henri de Bourbon, Duc de Montpensier gives up his claims to the Bouillon succession in exchange for an annuity.
August 5, 1601 - An agreement is signed between Henri de La Tour d'Auvergne and Charlotte's paternal uncle, Comte de Maulevrier, whose descendants continue to press their claims to Bouillon for the rest of the 17th century.
September 3, 1641 - Henri's son, Frédéric Maurice de La Tour d'Auvergne, renounces his claims to the reward of 30,000 livres promised by the prince-bishops of Liege in the Treaty of Tongeren.
1651 - Frédéric Maurice de La Tour d'Auvergne exchanges his sovereign princely titles for several ducal and comital titles in the Peerage of France. The agreement obligates France to restitute Bouillon to the La Tour d'Auvergne on the first opportunity.
1658 - Pursuant to the convention of 1641, the prince-bishops of Liège pay 150,000 guelders to Frederic Maurice, but he continues to style himself Duc de Bouillon despite their protests.
1676 - The French army takes Bouillon from the prince-bishops and restitutes it to the La Tour d'Auvergne, as was promised by the exchange of 1651.
1679 - The Treaties of Nijmegen confirm the La Tour d'Auvergne in possession of the duchy of Bouillon. Although a French contingent remains stationed in Bouillon, the dukes exercise sovereign rights to coin money, create peers and grant other titles. They also claim Saint-Hubert as one of their "peerages".
1757 - Charles Godefroy de La Tour d'Auvergne is welcomed in Bouillon as a sovereign duke, despite formal protests issued by the prince-bishop of Liège.
January 3, 1809 - The settlement of the Bouillon succession is endorsed by Emperor Napoleon.
1815 - The Congress of Vienna gives Bouillon to the Netherlands until the final settlement of the succession dispute between Philip Dauvergne (a British admiral by that time) and Charles-Alain-Gabriel de Rohan-Guemene (an Austrian general and the last duke's closest relative on his paternal side).
September 18, 1816 - Philip Dauvergne, ruined by the succession disputes, commits suicide, but the litigations concerning Bouillon drag on inconclusively until 1825.