Duchy of Normandy

The Duchy of Normandy was the Viking principality at the mouth of the Seine that became, for a century and a half, the hinge between France and England. In 911 the Frankish king Charles the Simple, unable to stop the Norse raids, granted the river mouth around Rouen to the chieftain Rollo by the Treaty of Saint-Clair-sur-Epte; Rollo accepted baptism, and his men, the Northmen, settled, married and within generations spoke French and endowed abbeys. The dukes pushed their borders to the Channel coast and raised the great Romanesque churches of Caen. In 1066 Duke William, holding a papal banner and a disputed promise from Edward the Confessor, crossed to England, won at Hastings, and joined the duchy to a cross-Channel empire that also held Maine and, for a time, Brittany's homage. The union made Normandy the staging ground of Anglo-French war: Henry I fought his brother for it, Henry II folded it into the Angevin dominion, and Philip Augustus, exploiting John's murders and excommunication, overran it in 1204 almost without resistance. The Treaty of Paris in 1259 had the English king formally surrender the duchy, though the Channel Islands stayed with the English crown and still do. Later French kings repeatedly granted the title to their heirs until 1469, when Normandy was absorbed into the royal domain and the duchy ended.