William of Poitiers ( 10201090) (LA: Guillelmus Pictaviensis; FR: Guillaume de Poitiers) was a Frankish priest of Norman origin and chaplain of Duke William of Normandy (William the Conqueror), for whom he chronicled the Norman Conquest of England in his Gesta Willelmi ducis Normannorum et regis Anglorum ("The Deeds of William, Duke of the Normans and King of the English") or Gesta Guillelmi II ducis Normannorum. He had trained as a soldier before taking holy orders. Life Little is known about William of Poitiers, with most information coming from Orderic Vitalis in his Historia Ecclesiactica, written in 1114–1115 and 1125. He was apparently born in Les Préaux, France, near Pont-Audemer to an influential knightly Norman family, probably about 1020. According to Orderic, William originally trained as a knight, which gave him a much greater insight into the details of war than the typical medieval clerical writer. About 1049 he decided to enter the church, turning away from his knightly duties. Once he turned to the priesthood, William studied at the renowned school of Saint Hilaire-le-Grand in Poitiers and was said by Orderic to have returned to Normandy 'more learned than all his friends and neighbours'. William was given positions of ecclesiastical authority, becoming chaplain to Duke William and archdeacon of Lisieux. However, he doesn't appear in any ecclesiastical or royal and ducal charters as might be expected from someone of such a position, which perhaps casts doubts over Orderic's account of William of Poitiers life. Little is known about his old age, and he probably retired into a religious house, or possibly political disgrace. This is implied by Orderic's statement that William of Poitiers was forced to stop writing his history of William the Conqueror due to ″unfavorable circumstances″, of which we do not know the nature. Possible links between William of Poitiers and Duke William's rebellious son Robert can be found, and may therefore provide an explanation for this. Gesta Guillelmi William of Poitiers wrote the Gesta Guillelmi some time after 1066. It tells the story of how Duke William prepared for, and achieved, the Conquest of England. It also justifies William's succession to the English throne. The bulk of the writing probably took place between 1071 and 1077. The Gesta Guillelmi is the earliest extended biography of any Duke of Normandy, and is an invaluable source for the Battle of Hastings in 1066. William of Poitiers was well