The War of the Breton 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, leading to a dispute over the duchy’s succession. Two main claimants emerged: Charles of Blois, supported by the French crown, and John de Montfort, backed by the English crown. The war involved several battles and shifting alliances, reflecting the broader Hundred Years' War context. Ultimately, the conflict ended with the Treaty of Guérande in 1365, which recognized John de Montfort as the Duke of Brittany, solidifying English influence in the region.