Duchy of Brittany

The Duchy of Brittany was a medieval feudal state and former European sovereign state that existed from approximately 939 to 1547. Established after the expulsion of Viking armies, its territory covered the northwestern peninsula of France, bordered by the Bay of Biscay, the English Channel, the river Loire, and Normandy. Initially politically unstable, the duchy experienced periods of alliance and conflict with the neighboring Duchy of Normandy. English influence was significant in the 12th century, with Henry II and his son Geoffrey holding ducal power. The French Crown later maintained influence, and a civil war, the Breton War of Succession, erupted in the 14th century. The duchy's independent nature began to decline after 1488, eventually becoming a dukedom of the Kingdom of France.