On 30 April 1341, John III, Duke of Brittany, died without a male heir. His half-brother, John of Montfort, was a candidate for the succession, which was also claimed by Joan of Penthièvre, niece of John III and wife of Charles of Blois, himself a nephew of the Philip VI, King of France. The King was, of course, favourable to his nephew. The Duchy of Brittany historically had a "semi-Salic" mode of inheritance; male primogeniture was followed unless no direct male descendants remained. At that point the closest female descendant inherited as Duchess, with her husband serving as Duke by "right of representation". The position of John of Montfort was legally founded on the belief that a brother was a closer heir than a beneficiary niece, and that the Salic form of inheritance adopted by the Kingdom of France should be followed. This argument was based on the fact that since 1297 Brittany had been a Duché-pairie, and that the legislation of the suzerain kingdom should therefore be applied. Challenges to the Salic law of the Franks had historically been rejected for the Kingdom of France, allowing Philip V to gain the throne in 1316, and Philip VI most recently. This made Edward III's support of John of Montfort quite ironic, in that the argument for Edward III to inherit the Kingdom of France was based on the opposing philosophy that the crown should be able to descend through a female line. A civil war, termed the War of the Breton Succession, then began and lasted 23 years. This conflict was also called La guerre de deux Jeanne, after the French names of the two duchesses in competition: Jeanne de Penthièvre and Jeanne de Flanders, wife of John of Montfort.
Early stages of the War (1341)
After the funeral of John III, Charles of Blois returned to the Court of France and John of Montfort returned to his Breton estate in Guérande. Then, incited by his wife, he went with a small army to Nantes where he was well received by the inhabitants who swore their loyalty. John then went to Limoges where he managed to obtain the ducal treasury. John returned to Nantes and was recognised as Duke in May 1341 by an assembly composed of members of the towns and minor nobles, but shunned by the major vassals with the exception of Hervé VII, Count of Léon. Thanks to the ducal treasury, he recruited mercenaries which allowed him to perform in June and July a 'great ride in Brittany' and take control of the duchy. John first gained Rennes, then Vannes and the places surrounding the Château de Suscinio, Auray, Hennebont, and then Quimperlé. Having failed to take the domains of Rohan, he submitted Quimper and Brest before descending to Carhaix, and then went back northward and captured Saint-Brieuc, Lamballe, Jugon, Dinan, Dol-de-Bretagne, and returned to Nantes via Ploërmel. Always accompanied by Hervé VII of Léon, John obtained the submission, if not the support, of some of the major nobles who possessed several of these strongholds and had been loyal to Charles of Blois. However it would probably require getting Josselin, or the support of the high secular clergy and great lords, or more, to control the domains of the Penthièvres and the House of Rohan, which represented about two-thirds of Brittany. John also went to England and met with Edward III of England in Windsor, who promised him military assistance and invested him with the Honour of Richmond. Charles of Blois then made an appeal to Philip VI, who summoned John of Montfort to a Court of Peers session in Conflans in September 1341. In this context by the judgment of Conflans, the Duchy of Brittany was attributed to Charles of Blois. Philip VI agreed to receive l'hommage lige of Charles of Blois on behalf of his wife, and confiscated from John of Montfort the French lands of the County of Montfort-l'Amaury, as well as the Viscounty of Limoges that he held more unduly. In October 1341, Charles of Blois and John II, Duke of Normandy, put together an army and penetrated into Brittany. They managed to retrieve a number of strongholds which had been lost, including Nantes, which relented on 21 November 1341 after three weeks of siege. John of Montfort was captured and imprisoned in the Louvre in Paris. Despite the change of camp of Hervé VII de Leon, Joanna, the wife of John of Montfort, continued the armed struggle supported by his allies.
Subsequent stages of the War (1342–1345)
After a winter break that ended on 15 April 1342, Charles of Blois resumed the fight and regained a large part of Brittany between May and September 1342. King Edward III of England decided to intervene on behalf of the House of Montfort. Charles de Blois failed to take Hennebont, which was defended by Joanna of Flanders, while Robert III of Artois was mortally wounded besieging Vannes in vain leading an English contingent. In January 1343, through Pope Clement VI, a truce was signed at Malestroit to bring peace and the liberation of John of Montfort. The latter was released in September 1343 and retired to England 27 March 1345. His return to the struggle with reinforcements provided by King Edward III of England put an end to the truce. John of Montfort unsuccessfully laid siege to Quimper, then fell ill and died in Hennebont on 16 September 1345.
Tomb of John of Monfort
He was buried in the convent of the Dominicans of Quimperlé where his tomb, which had already been desecrated, was found again in December 1883. His remains are now in the Church of Sainte-Croix de Quimperlé.
