The Breton War of Succession (1341-1364) was a conflict in the region of Brittany in northwestern France. It arose after the death of John III, Duke of Brittany, who left no clear heir. Two main claimants emerged: Charles of Blois, supported by the French crown, and John de Montfort, backed by the English crown. This rivalry led to a series of battles and shifting alliances. The war was marked by significant events, including the Battle of Auray in 1364, which ultimately favored John de Montfort. His victory solidified his claim to the duchy, leading to the eventual recognition of his son, John IV, as the Duke of Brittany. The conflict had lasting effects on the region's political landscape.