Viking-descended duchy that became one of medieval Europe's most powerful states; its duke conquered England in 1066, uniting the duchy with the English crown.
Conquered by Philip II of France in 1204 when Rouen, the ducal capital, surrendered on 24 June 1204, ending some 293 years of Norman autonomy after King John of England failed to mount a relief effort; the 1259 Treaty of Paris confirmed French possession.
History of the Duchy of Normandy from its Viking origins.