Individual Details

Marriage

Conflict with Church and wife, 1102–1118
William, like his father and many magnates of the time, had a rocky relationship with the Church. He was excommunicated twice, the first time in 1114 for an alleged infringement of the Church's tax privileges. His response to this was to demand absolution from Peter, Bishop of Poitiers. As the bishop was at the point of pronouncing the anathema, the duke threatened him with a sword, swearing to kill him if he did not pronounce absolution. Bishop Peter, surprised, pretended to comply, but when the duke, satisfied, released him, the bishop completed reading the anathema, before calmly presenting his neck and inviting the duke to strike. According to contemporaries, William hesitated a moment before sheathing his sword and replying, "I don't love you enough to send you to paradise."
William was excommunicated a second time for "abducting" the Viscountess Dangerose (Dangerosa), the wife of his vassal Aimery I de Rochefoucauld, Viscount of Châtellerault. The lady, however, appears to have been a willing party in the matter. He installed her in the Maubergeonne tower of his castle in Poitiers (leading to her nickname La Maubergeonne), and, as related by William of Malmesbury, even painted a picture of her on his shield.
Upon returning to Poitiers from Toulouse, Philippa was enraged to discover a rival woman living in her palace. She appealed to her friends at court and to the Church; however, no noble could assist her since William was their feudal overlord, and whilst the Papal legate Giraud (who was bald) complained to William and told him to return Dangerose to her husband, William's only response was, "Curls will grow on your pate before I part with the Viscountess." Humiliated, Philippa chose in 1116 to retire to the Abbey of Fontevrault, where she was befriended, ironically, by Ermengarde of Anjou, William's first wife. While in residence she may have had direct conversations or correspondence with Countess Adela of Blois, who was in constant contact with Fontevrault from Marcigney abbey. Philippa did not survive there long, however: the abbey records state that she died on 28 November 1118.

Later career, 1118–1126
Relations between the Duke and his elder son William also became strained—although it is unlikely that he ever embarked upon a seven-year revolt in order to avenge his mother's mistreatment, as Ralph of Diceto claimed, only to be captured by his father. Other records flatly contradict such a thing. Ralph claimed that the revolt began in 1113; but at that time, the young William was only thirteen and his father's liaison with Dangerose had not yet begun. Father and son improved their relationship after the marriage of the younger William to Aenor of Châtellerault, Dangerose's daughter by her husband, in 1121.
William was readmitted to the Church around 1120, after making concessions to it. However, he was after 1118 faced with the return of his first wife, Ermengarde, who had, upon the death of Philippa, stormed down from Fontevrault to the Poitevin court, demanding to be reinstated as the Duchess of Aquitaine—presumably in an attempt to avenge the mistreated Philippa. In October 1119, she suddenly appeared at the Council of Reims being held by Pope Calixtus II and demanded that the Pope excommunicate William (again), oust Dangerose from the ducal palace, and restore herself to her rightful place. The Pope "declined to accommodate her"; however, she continued to trouble William for several years afterwards, thereby encouraging him to join the Reconquista efforts underway in Spain.
Between 1120 and 1123 William joined forces with the Kingdoms of Castile and León. Aquitanian troops fought side by side with Castilians in an effort to take Cordoba. During his sojourn in Spain, William was given a rock crystal vase by a Muslim ally that he later bequeathed to his granddaughter Eleanor. The vase probably originated in Sassanid Persia in the seventh century.
In 1122, William lost control of Toulouse, Philippa's dower land, to Alfonso Jordan, the son and heir of Raymond IV, who had taken Toulouse after the death of William IV. He did not trouble to reclaim it. He died on 10 February 1126, aged 55, after suffering a short illness.