William of Jumièges (Guillaume de Jumièges) was a contemporary of the events of 1066, and one of our earliest writers on the subject of the Norman Conquest. He is himself a "shadowy figure", only known by his dedicatory letter to King William as a monk of Jumièges. "Since he also mentions that he was an eyewitness of some events from the reign of Richard III (1026-7), it seems reasonable to assume that he was born some time about the year 1000. He probably entered the monastery during the first quarter of the eleventh century and received his education from Thierry de Mathonville." According to Orderic Vitalis, William's nickname was "Calculus". The meaning behind this nickname is unknown. His death, post 1070, is unrecorded. He was a Norman writing from a Norman point of view. Although only a monk with evidently no military training, he wrote with pride in the accomplishments of his people.
William of Jumièges was the original compiler of the history known as The Gesta Normannorum Ducum ("Deeds of the Dukes of the Normans"), written in about 1070. This was built upon the framework of an earlier history compiled by Dudo of Saint-Quentin, De moribus et actis primorum Normannorum ducum, between c. 996 and c. 1015. This work was commissioned by Duke Richard I,