William X, Duke of of Aquitaine

Who was William X, Duke of of Aquitaine?

William X, called the Saint, was Duke of Aquitaine, Duke of Gascony, and Count of Poitou from 1126 to 1137. He was the son of William IX by his second wife, Philippa of Toulouse.

William was born in Toulouse during the brief period when his parents ruled the capital. His birth is recorded in the Chronicle of Saint-Maixent for the year 1099: Willelmo comiti natus est filius, equivoce Guillelmus vocatus. Later that same year, much to Philippa's ire, Duke William IX mortgaged Toulouse to Philippa's cousin, Bertrand of Toulouse, and then left on Crusade.

Philippa and her infant son William X were left in Poitiers. When Duke William IX returned from his unsuccessful crusade, he took up with Dangerose, the wife a vassal, and set aside his rightful wife, Philippa. This caused strain between father and son, until 1121 when William X married Aenor de Châtellerault, a daughter of his father's mistress Dangerossa by her first husband, Aimery.

William had three children with Aenor:

Eleanor, who later became heiress to the Duchy;

Petronilla, who married Raoul I of Vermandois;

William Aigret, who died at age 4 in 1130, about the time their mother Aenor de Châtellerault died.