Duke of Richelieu

Duke of Richelieu was a title of French nobility. It was created on 26 November 1629 for Armand Jean du Plessis de Richelieu (known as Cardinal Richelieu) who, as a Roman Catholic clergyman, had no issue to pass it down to. It instead passed to his great-nephew, Armand Jean de Vignerot, grandson of his elder sister Françoise du Plessis (1577–1615), who had married René de Vignerot, Seigneur de Pontcourlay († 1625).

Armand Jean de Vignerot added the cardinal's surname of "du Plessis" to his own, took the cardinal's coat of arms and received the titles of Duke of Richelieu and Peer of France by letters patent in 1657.

Two new reversions of the title occurred in 1822 and 1879. In effect, the 5th Duke of Richelieu died without an heir, but he gained permission for the title of Duke of Richelieu to pass to the son of his half-sister Simplicie, daughter of Antoine-Pierre de La Chapelle de Saint-Jean de Jumilhac, with reversion to the descendants of his younger brother should he die without a male heir, thus effectively passing the title to his nephew.

The title became extinct in 1952 upon the death of the 8th Duke of Richelieu, Marie Odet Jean Armand de La Chapelle de Saint-Jean de Jumilhac, son of the 7th Duke of Richelieu and of Alice Heine (1858–1925). Alice was widowed in 1880 and remarried to Prince Albert I of Monaco in 1889.