CHARLES (c. 1319-1364), duke of Brittany, known as CHARLES OF BLOIS and CHARLES OF CHATILLON, was the son of Guy of Chatillon, count of Blois (d. 1342), and of Marguerite of Valois, sister of Philip VI. of France. In 1337 he married Jeanne of Penthievre (d. 1384), daughter of Guy of Brittany, count of Penthievre (d. 1331), and thus acquired a right to the succession of the duchy of Brittany. On the death of John III. duke of Brittany, in April 1341, his brother John, count of Montfort l'Amaury, and his niece Jeanne, wife of Charles of Blois, dis puted the succession. Charles of Blois, sustained by Philip VI., captured John of Montfort, who was supported by King Edward III. at Nantes, besieged his wife Jeanne of Flanders at Henne bont, and took Quimper and Guerande . But next year his partisans were defeated at Cadoret, and in June 1347 he was himself wounded and taken prisoner at Roche-Derrien. He was not liberated until 1356, when he continued the war against the young John of Montfort, and perished in the battle of Auray, on Sept. 29, 1364.