Louis Marie Florent du Châtelet

Louis Marie Florent de Lomont d'Haraucourt, duke of Châtelet (20 November 1727, Semur-en-Auxois, Côte-d'Or - 13 December 1793, Paris), was a French army officer, nobleman and diplomat. He served as (among other roles) governor of Semur-en-Auxois in Burgundy. He was guillotined in 1793 aged 66. He is also notable as the son of Émilie du Châtelet, scientist and lover of Voltaire.

Birth, youth and marriage
On 20 June 1725 his father Florent-Claude du Chastellet married Gabrielle Émilie Le Tonnelier de Breteuil, who became known as Émilie du Châtelet. Like many marriages among the nobility, theirs was an arranged marriage. The couple had little in common, but the proprieties were observed in accordance with contemporary norms. The Marquis Florent-Claude du Chastellet and Émilie du Châtelet had three children: Francoise Gabriel Pauline, who was born on June 30, 1726, Louis Marie Florent, born on November 20, 1727, and Victor-Esprit, born at Paris in 1734, who died in infancy. After bearing three children, Émilie, considering her marital responsibilities fulfilled, made an agreement with her husband to live separate lives while still maintaining one household.

Descendants
The Duke of Châtelet had no children of his own, so he adopted his wife’s niece instead. Diane-Adélaïde de Damas d'Antigny. She was born in Paris (January 25, 1761), and at age sixteen, was married to Charles-François de Simiane (August 12, 1777). She then became a Countess. Her husband was a homosexual, so she sought comfort elsewhere. Gilbert du Motier, Marquis de Lafayette had served in the American Revolution with Charles-François de Simiane; and in the 1780s, he had a long affair with his wife, Madame de Simiane. When Charles-François Simiane died (March 27, 1787), Diane-Adélaïde never married again. She spent the rest of her years at Château de Cirey, until her death (April 9, 1835).