Duke of Normandy as the reign of William II (1035–87), the ruler of Normandy could style himself "prince and duke, count of Normandy" as if unsure what his title should be. The literal Latin equivalent of "Duke of Normandy", "dux Normanniae", was in use by 1066, but it did not supplant "dux Normannorum" until the Angevin period (1144–1204), at a time when Norman identity was fading. Richard I experimented with the title "marquis" ("marchio") as early as 966, when it was also used in a diploma of King Lothair. Richard II occasionally used it, but he seems to have preferred the title duke.
William III, Duke of Aquitaine William III, Duke of Aquitaine William III (915 – 3 April 963), called Towhead (, ) from the colour of his hair, was the "Count of the Duchy of Aquitaine" from 959 and Duke of Aquitaine from 962 to his death. He was also the Count of Poitou (as William I) from 935 and Count of Auvergne from 950. The primary sources for his reign are Ademar of Chabannes, Dudo of Saint-Quentin, and William of Jumièges. William was son of Ebalus Manzer and Emilienne. He was born in Poitiers. He claimed the Duchy of Aquitaine from his father's death, but