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 the Conqueror of the year on which fighting was permitted. Although the Battle of Val-ès-Dunes marked a turning point in William's control of the duchy, it was not the end of his struggle to gain the upper hand over the nobility. The period from 1047 to 1054 saw almost continuous warfare, with lesser crises continuing until 1060. William's next efforts were against Guy of Burgundy, who retreated to his castle at Brionne, which William besieged. After a long effort, the duke succeeded in exiling Guy in 1050. To address the growing power of the Count of Anjou, Geoffrey Martel, William joined with