CHARLES (c. 1319-1364)  , duke of Brittany, known as CHARLES OF BLOIS and CHARLES OF CHATILLON, was the son of Guy of Chhtillon, 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 Montfortl'Amaury, and his niece Jeanne, wife of Charles of Blois, disputed 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 Hennebont, and took Quimper and Guerande (1344) . 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 the 29th of September 1364 . Charles bore a high reputation for piety, and was believed to have performed miracles . The Roman Church has canonized him . See Simeon Luce, Histoire de Bertrand du Guesclin et de son epoque (Paris, 1876) .