Joanna of Flanders ( 1295 – September 1374) was Duchess of Brittany by her marriage to John of Montfort. Much of her life was taken up in defence of the rights of her husband and, later, son to the dukedom, which was challenged by the House of Blois during the War of the Breton Succession. Known for her fiery personality, Joanna led the Montfortist cause after her husband had been captured, and began the fight-back, showing considerable skill as a military leader. Shortly after taking refuge in England, she was confined to Tickhill Castle by order of King Edward III. Joanna was highly praised by the chronicler Jean Froissart for her courage and energy. Because of her feats of leadership, David Hume described her as "the most extraordinary woman of the age". Life Joanna was the daughter of Louis I, Count of Nevers and Joan, Countess of Rethel, and the sister of Louis I, Count of Flanders. She married John of Monfort in March 1329. John of Monfort claimed the title of Duke of Brittany, although his claim was contested by Joan of Penthièvre and her husband, Charles of Blois. Joanna and John had two children: John IV, Duke of Brittany (1339–1399) Joan of Brittany, Baroness of Drayton (1341 – aft. 20 October 1399), born at the onset of the War of the Breton Succession, married before 21 October 1385 to Ralph Basset, 4th Baron Basset de Drayton War of the Breton Succession When John III, Duke of Brittany died childless in 1341, he left behind a contentious succession dispute. For many years he tried to find means to ensure that the children of his stepmother, Yolande of Dreux would not inherit the Duchy, including trying to have her marriage to his father annulled. At this time he declared his heir to be his niece Joan of Penthièvre. However he reconciled with his half brother, John of Monfort, shortly before his death, and indicated that he was to be the successor. Thus upon the death of Duke John III, there were two rival claimants for Brittany: the House of Montfort, led by John of Montfort and his wife Joanna, and the House of Blois led by Charles of Blois and his wife Joan of Penthièvre. John of Montfort went to Paris to be heard by King Philip VI of France. Philip was an uncle of Charles, and he imprisoned John,