Sancho III of Navarre
Count William aided the duke against the Boso II of La Marche and in return the duke supported the count's extension of his authority into the Bordelais. William was regularly present with the duke's court from about 1000 until October 1010, when an important meeting involving the duke, King Robert II of France, King Sancho III of Navarre and Duke Sancho VI of Gascony took place at the church of Saint Jean d'Angély. His absence from this meeting probably indicates the growing enmity between Duke William and Fulk of Anjou.