Research Notes:

The Chronicle of Adémar de Chabannes names "Willelmum" as son of "Willelmum" (son of "Willelmo Capite stupæ") and his wife "filiam Tetbaldi Campenensis…Emmam". "Vuillelmus dux Aquitanorum" donated property to Saint-Jean d'Angély for the soul of "…filios meo Vuilelmo…" by charter dated [971]. "Willelmus Aquitanorum comes et dux et uxor mea Hemma et filius noster equivocus Willelmus" donated property to Saint-Maixent by charter dated Dec 992. His mother retained custody of Guillaume during her separation from his father, but returned him to Poitiers in May 988. "Guilelmus Aquitaniencum dux" founded a hospital near Saint-Hilaire de Poitiers by charter dated Jan 989, subscribed by "Emma comitissa, Guillelmi filium eius, Guilelmi comitis Engolismæ…".

He succeeded his father in 993 as GUILLAUME V "le Grand" Duke of Aquitaine, GUILLAUME III Comte de Poitou. He summoned a council at Poitiers in 1000 which decided that future disputes should be settled by justice not recourse to arms. Duke Guillaume enjoyed close relations with Emperor Heinrich II, with whom he exchanged gifts. Rebels in Italy, opposed to the election of Konrad II King of Germany in 1024, offered the throne of Italy to Duke Guillaume, who refused the offer. Duke Guillaume maintained an active correspondence with leading churchmen, men of science and political leaders and established a library for which he commissioned the transcription of manuscripts.

He abdicated in favour of his eldest son in 1029 and became a monk at the Abbey of Maillezais. ¹