Charles Genevieve Louis Augnste Andre Timothee D' Eon De Beaumont, commonly called the chevalier d'Eon, a French diplomatist, who owes his notoriety to doubts which long existed as to his sex, born in Tonnerre, Burgundy, Oct. 5, 1728, died in London, May 21,1810. He was of good family, was well educated, became a doctor of canon and civil law, and an advocate before the parliament of Paris, and at the outset of his career applied himself with some success to literature. In 1755 Louis XV. employed him in a delicate diplomatic mission to Russia in company with the chevalier Douglas. Favored by a beardless face, he assumed the dress of a woman, and, blending a woman's tact with a politician's cunning, gained the good graces of the empress Elizabeth, became her reader, and having bent her mind to the wishes of the French court, went back to Paris to announce his success. He immediately revisited St. Petersburg in male attire, passed himself upon Elizabeth as the brother of her former favorite, was again successful in his negotiations, and on his way back to France appeared as envoy at Vienna. Having held a commission in the army, he was promoted to a captaincy of dragoons in 1759, served with the forces on the Rhine, and acted as aide-decamp to Marshal de Broglie during the latter campaigns of the seven years' war.

He was then secretary of embassy, and afterward minister plenipotentiary, at London; but being superseded in 1763 by the count de Guerchy, and mortified by being named secretary to his successor, he published a complete account of all the negotiations in which he had been engaged, exposed many secrete of the French court, and reflected with equal severity upon friends and enemies. Among the victims of his slander wasDe Guerchy, who brought an action in the court of king's bench, in which D'£on was convicted of libel in July, 1764, and was finally outlawed. He continued, however, to reside in England, subsisting for a time by borrowing and various expedients, and afterward on a pension which Louis XV. allowed him for secret services; and after the return of De Guerchy to France, he acted as the representative of the court of Versailles, though not officially recognized as such. About 1763 rumors respecting his sex, which received color from his adventure in St. Petersburg, his appearance, his manners, and the reports spread by De Guerchy, became common topics of conversation in the British capital; bets to a large amount were laid that he was a woman, and a wager of this sort became matter for a lawsuit, in which the plaintiff, having brought witnesses to swear that D'£on was a female, obtained a verdict for £700. In 1777 he went to Versailles, where Louis XVI., for reasons which have never been made known, forced him to adopt a woman's dress.

He returned to England in this garb in 1783, and supported himself in London by the sale of his library, by giving exhibitions of his skill in fencing with the famous M. St. George and Mr. Angelo, and by a pension from George III. On the outbreak of the revolution he offered his services in a military capacity; but they were declined, and he passed the rest of his days in poverty in England, retaining till his death the garb which had been forced upon him 33 years before. A post mortem examination left no doubt of his being a man. He wrote a number of historical, political, and other works. The Memoires attributed to him are spurious. EOS. See Aueoea.