Charles of Blois (1319 – 29 September 1364) claimed the title Duke of Brittany, from 1341 to his death. Charles was born in Blois, the son of Guy I of Blois-Châtillon, count of Blois, by Margaret of Valois, a sister of king Philip VI of France. He was a devout man, who took piety to the extreme of mortifying his own flesh. It is said that he placed pebbles in his shoes, wore ropes tight with knots near his flesh and confessed every night in fear of sleeping in a state of sin. He was nevertheless an accomplished military leader, who inspired loyalty by his religious fervour.