Presumably the Duc de Lauzun, the penniless Gascon nobleman who became Louis XIV's favourite and nearly married La Grande Mademoiselle, the King's cousin; Mme de Sévigné's account of the incident is well known. Lauzun was disgraced and exiled, but recovered a measure of favour after rescuing the wife and son of James II during the English Revolution of 1688. He eventually became Saint-Simon's brother-in-law. See also X, 19.