James Scott Monmouth, duke of, supposed son of Charles II., king of Great Britain, born in Rotterdam, April 9, 1649, executed in London, July 15, 1685. His mother was Lucy Walters, who was at first mistress of Algernon Sidney, and afterward of his brother Robert; and the latter was by some reputed the father of Monmouth. While Charles was in Holland, Lucy Walters became his mistress. He acknowledged her son to be his offspring, and was throughout life strongly attached to him. The boy was known as James Crofts, because he was for some time in the charge of Lord Crofts, and passed for his relative. When he was taken to England, in 1662, he was very accomplished and very handsome. He was first made duke of Orkney, but the title was changed to that of Monmouth. He was also created baron of Tyndale and earl of Doncaster at the same time, Feb. 19, 1663. He served on board the fleet of the duke of York in 1665, and was in the battle of Lowestoft, June 3. He married while very young Anne, daughter and sole heir of Francis Scott, earl of Buccleuch, and assumed her name.

They were created duke and duchess of Buccleuch, earl and countess of Dalkeith, and baron and baroness of Whitchester and Ash-dale in Scotland, in 1673. In 1670 he became captain general of all the king's fortresses, and a privy councillor, and was allowed privileges at court which could be claimed only by persons of the blood royal. At first Monmouth and his uncle, the duke of York, were friends, but they soon became rivals in love and politics. Those who dreaded the accession of York to the throne (the king having no legitimate children, nor expecting any) endeavored to have Monmouth recognized as heir presumptive. When England joined France in the war against Holland, Monmouth was sent at the head of 6,000 troops to act under Louis XIV. in 1672. He served in two campaigns with considerable distinction, and was made a lieutenant general by the French king. Subsequently, as lord general of the king's forces in Flanders, he took part in the battle of St. Denis. He had been made commander-in-chief of the armies of England and Scotland, and was known as "the Protestant duke." He encouraged the Rye House plot, and his designs on the succession to the throne were much favored by Shaftesbury and his associates, and by the extreme unpopularity of the duke of York, who was a Catholic, and who was compelled to leave the country.

Monmouth defeated the Scotch Covenanters, June 22, 1679, at Both well. As he treated the rebels mildly, and would willingly have spared them all, he was accused of favoring rebellion, and was compelled to resign his office of lord general and to go to Holland. Thence he returned to England without leave, and on his refusal to quit the kingdom his offices were taken from him. He now headed the opposition to the court, and his pretensions to the crown were vigorously pressed by his followers, rather on a popular than on a legal basis; but when the duke of York returned to court, the story of the marriage of Charles II. and Lucy Walters was gravely urged, and the king deemed it necessary to deny it in the most public and formal manner. The part Monmouth had in the conspiracies of 1683 led to his flight to Holland, after considerable negotiation with the king for pardon. When Charles II. died, Feb. 6, 1685, he left the Hague, and, deluded by the suggestions of British exiles, headed a small expedition, which arrived at Lyme Regis, June 11. At first the duke met with some success; but his forces were beaten at Sedge-moor, July 6, and on the 8th he was captured and taken to London, where he had an interview with James II., of whom he vainly begged his life in abject terms.

He was executed under an act of attainder two days after his arrival in the capital. His followers continued for many years to believe that he was alive, and it was supposed by some that he was the man with the iron mask who was so long a prisoner in the Bastile. His wife, a woman of superior talents, from whom he had been separated, survived him nearly 47 years, and married Charles, third Lord Cornwallis. She is the duchess of Scott's "Lay of the Last Minstrel," and Monmouth is the Absalom of Dryden's "Absalom and Achitophel".