Charles, Duke of Brittany

Charles of Blois-Châtillon "the Saint", was the legalist Duke of Brittany from 1341 to his death via his marriage to Joan of Penthiève, holding the title against the claims of John of Montfort. The cause of his possible canonization was the subject of a good deal political maneuvering on the part of his cousin, Charles V of France who endorsed it, and his rival, Montfort, who opposed it. The cause fell dormant after Pope Gregory XI left Avignon in 1376, but was revived in 1894. Charles of Blois was beatified in 1904.