Duke of Enghien (French: Duc d'Enghien, pronounced [dɑ̃ɡɛ̃] with a silent i) was a noble title pertaining to the House of Condé.
However, the necessary registration process was not completed, so the title became extinct at his death in 1569.
In spite of this legal loophole, from 1569 to 1689 the eldest son of the Prince of Condé also held the title of Duke of Enghien.
The most famous of them is Louis II, also known as the Great Condé, who held the title of Duke of Enghien from his birth in 1621 to his father's death in 1646.
Most often it refers to Louis-Antoine-Henri de Bourbon-Condé, duc d'Enghien (1772–1804), the son of Louis Henry II, whose execution on trumped-up charges in 1804 during the French Consulate removed any hope of reconciliation between Napoleon Bonaparte and the House of Bourbon.