The Duke was the only son of Louis Henry II, Prince of Condé, and of Louise Marie Thérèse Bathilde d'Orléans, the daughter of Louis Philippe I, Duc d'Orléans and the sister of the future Philippe Egalité. As a member of the reigning House of Bourbon, he was a Prince du Sang. He was born at the Château de Chantilly.
He was educated privately by the Abbé Millot, and in military matters by Commodore de Vinieux. He early on showed the warlike spirit of the House of Condé, and began his military career in 1788. On the outbreak of the French Revolution, he emigrated with his father and grandfather a few days after the fall of the Bastille, and remained in exile, seeking to raise forces for the invasion of France and the restoration of the old monarchy. In 1792, on the outbreak of French Revolutionary Wars, he held a command in the corps of émigrés organized and commanded by his grandfather, the Prince de Condé. This Army of Condé shared in the Duke of Brunswick's unsuccessful invasion of France.
After this, the young duc continued to serve under his father and grandfather in the Condé army, and on several occasions, distinguished himself by his bravery and ardour in the vanguard. On the dissolution of that force after the peace of Lunéville (February 1801) he married privately Charlotte de Rohan-Rochefort, niece of the Cardinal de Rohan, and took up his residence at Ettenheim in Baden, near the Rhine.
Early in 1804, Napoleon, then First Consul of France, heard news which seemed to connect the young duke with the Cadoudal-Pichegru conspiracy then being tracked by the French police. The news ran that the duke was in company with Charles François Dumouriez and had made secret journeys into France. This was false; the acquaintance was Thumry, a harmless old man, and the duke had no dealings with either Cadoudal or Pichegru. Napoleon gave orders for the seizure of the duke. French dragoons crossed the Rhine secretly, surrounded his house and brought him to Strasbourg (March 15, 1804), and thence to the Château de Vincennes, near Paris. There a commission of French colonels was hastily convened to try him.
Meanwhile, Napoleon had found out the true facts of the case, and the accusations were hastily changed. The duke was now charged chiefly with bearing arms against France in the late war, and with intending to take part in the new coalition then proposed against France — these latter charges were more accurate than the original ones and, given his history of fighting against his own nation, it would be difficult to argue that he was wholly innocent; rather the argument is whether or not his actions were sufficiently severe to merit execution. Claims that he presented a threat to the life of the First Consul are probably exaggerated. The colonels hastily and most informally drew up the act of condemnation, being incited thereto by orders from Anne Jean Marie René Savary, who had come charged with instructions. Savary intervened to prevent any chance of an interview between the condemned and the First Consul, and the duke was shot in the moat of the castle, near a grave which had already been prepared.
He was the last descendent of the House of Condé; his grandfather and father died after him, but without producing further heirs. In 1816, his bones were exhumed and placed in the chapel of the castle. It is now known that Joséphine and Madame de Rémusat had begged Napoleon for mercy towards the duke; but nothing would bend his will. The blame which the apologists of the emperor have thrown on Talleyrand or Savary is undeserved. On his way to St. Helena and at Longwood, he asserted that, in the same circumstances, he would do the same again; he inserted a similar declaration in his will.
The judicial murder of Enghien shocked the aristocrats of Europe, who still remembered the bloodletting of the Revolution and who lost whatever conditional respect they may have entertained for Napoleon. Either Antoine Boulay de la Meurthe (deputy from Meurthe in the Corps législatif) or Napoleon's chief of police, Joseph Fouché, said about his execution, "It is more than a crime; it is a political fault." ("C'est pire qu'un crime, c'est une faute."), a statement often rendered in English as "It was worse than a crime; it was a mistake." The statement is also sometimes attributed to French diplomat Charles Maurice de Talleyrand-Périgord.
The group about Mortemart immediately began discussing the murder of the Duc d'Enghien. "After the murder of the Duc, even the most partial ceased to regard [Buonaparte] as a hero. If to some people, he ever was a hero, after the murder of the duc there was one martyr more in heaven and one hero less on earth." The vicomte said that the Duc d'Enghien had perished by his own magnanimity, and that there were particular reasons for Buonaparte's hatred of him.(...)
It was an anecdote, then current, to the effect that the Duc d'Enghien had gone secretly to Paris to visit Mademoiselle George; that at her house he came upon Bonaparte, who also enjoyed the famous actress' favors, and that in his presence Napoleon happened to fall into one of the fainting fits to which he was subject, and was thus at the Duc's mercy. The latter spared him, and this magnanimity Bonaparte subsequently repaid by death. The story was very pretty and interesting, especially at the point where the rivals suddenly recognized one another; and the ladies looked agitated.
The actress Marguerite-Joséphine Wiemer, known as "Mademoiselle George", was indeed Napoleon's mistress, but there is no evidence that the Duc d'Enghien had anything to do with her, or that the story preserved to posterity by Tolstoy's masterpiece was anything more than one of the pieces of gossip and conspiracy theories current around Europe at the time.