Maximilicn De Betliune Sully, baron de Rosny, duke of, a French statesman, born at Rosny, near Mantes, Dec. 13, 1560, died near Chartres, Dec. 22, 1641. He belonged to a noble Protestant family, and followed King Henry of Navarre in all his wars, and became his chief adviser. When his master, on the death of Henry III., claimed the throne of France, Rosny advised him to turn Catholic in order to reconcile the majority of the nation to his cause. On a secret mission to Queen Elizabeth of England, he secured her assistance to Henry IV., and he was instrumental as an engineer in taking Dreux in 1593, Laon in 1594, La Fere in 1596, and Amiens in 1597. In 1597 he was appointed superintendent of finance, and became in fact the chief minister of Henry IV. He reformed the financial system, and cancelled the public debt, which amounted to 332,000,000 livres, remitting 20,000,000 taxes in arrears, alleviating the annual taxation, and gathering a reserve of 17,000,000, which was deposited in the Bastile. He fostered agriculture, made the grain trade free, suppressed tolls and prohibitions, built or improved highways and roads, constructed canals, and encouraged drainage and mining.

He had received the title of marquis of Rosny in 1601, and was created duke of Sully in 1606. At the death of Henry IV. in 1610 the reserve in the Bastile amounted to 42,000,000. Sully remained as chief minister some time longer, but his severity and rigid principles becoming-obnoxious to Maria de' Medici and her advisers, he left the court in 1611, and resigned most of his offices and dignities. Cardinal Richelieu in 1634 made him marshal of France. During his retirement he composed his personal memoirs, Memoires des sages et royales economies d'Etat de Henry le Grand (4 vols, fol, 1634-'62, several times reprinted; English translation by Mrs. Lennox, 3 vols. 4to, London, 1756; new ed., 5 vols. 8vo, 1854-'6). - See Eloge his-torique de Sully, by Perrens (Paris, 1871).