Documents of his reign state that his grandfather came from Iberia, lending credence to "phantasmagorical" genealogies placing the origins of García II Sánchez across the Pyrenees.
He inherited the county of Bordeaux from his cousin William the Good, son of his aunt Entregodis, who married one Raymond, and united it to Gascony permanently.
During the reign of William II, his brother Gombald, the "Bishop of the Gascons", established control over all the dioceses in Gascony and eventually became Archbishop of Bordeaux.
It has been proposed, however, that the duke of Gascony was on a pilgrimage to the shrine of Saint James at Compostela when, in an emergency, he took command of the defences during a Viking attack.
[4] William married Urraca Garcés (died before 1008),[5] a daughter of king García Sánchez I of Pamplona (927–70) and widow of count Fernán González of Castile.