Duke of Bouillon was a hereditary title borne until the early nineteenth century by members of the House of La Tour d'Auvergne as rulers of the duchy of Bouillon , a small state located between Luxembourg, Champagne, and the Three Bishoprics. Once the dynasty became extinct in 1802 and the duchy lost its independence to the Dutch kings who obtained the new Grand Duchy of Luxembourg in 1815, the title became the source of dispute among cognatic relatives and alleged agnatic heirs of the last reigning duke, Jacques Léopold de La Tour d'Auvergne.