William VIII, Duke of Aquitaine

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William VIII, Duke of Aquitaine
Bornc. 1025
Died(1086-09-25)25 September 1086 (aged 61)
Noble familyHouse of Poitiers
Spouse(s)Garsende of Périgord
Hildegarde of Burgundy
FatherWilliam V of Aquitaine
MotherAgnes of Burgundy

William VIII (c. 1025 – 25 September 1086), born Guy-Geoffrey (Gui-Geoffroi), was duke of Gascony (1052–1086), and then duke of Aquitaine and count of Poitiers (as William VI) between 1058 and 1086, succeeding his brother William VII (Pierre-Guillaume).


Guy-Geoffroy was the youngest son of William V of Aquitaine by his third wife Agnes of Burgundy.[1] He was the brother-in-law of Henry III, Holy Roman Emperor who had married his sister, Agnes de Poitou.

He became Duke of Gascony in 1052 during his older brother William VII's rule. Gascony had come to Aquitanian rule through William V's marriage to Prisca (a.k.a. Brisce) of Gascony, the sister of Duke Sans VI Guilhem of Gascony.

William VIII was one of the leaders of the allied army called to help Ramiro I of Aragon in the Siege of Barbastro (1064). This expedition was the first campaign organized by the papacy, namely Pope Alexander II, against a Muslim town and stronghold in the Emirate of Zaragoza, and the precursor of the later Crusades movement. Aragon and its allies conquered the city, killed its inhabitants and collected an important booty.

However, Aragon lost the city again in the following years. During William VIII's rule, the alliance with the southern kingdoms of modern Spain was a political priority as shown by the marriage of all his daughters to Iberian kings.

Marriage and children[edit]

William married three times and had at least five children. After he divorced his first two wives, the first due to infertility, he married a third time to a much younger woman who was also his cousin Robert I of Burgundy's daughter. This marriage produced a son, but William VIII had to visit Rome in the early 1070s to persuade the pope to recognize his children from his third marriage as legitimate.

  1. Agnes, married Alfonso VI of Castile[3]
  1. Agnes (died 1097), married Peter I of Aragon[2]
  2. William IX of Aquitaine, his heir


  1. ^ Dunbabin states Audeart of Burgundy married William.[2]


  1. ^ Bachrach 1993, p. 268.
  2. ^ a b c d Dunbabin 1985, p. 384.
  3. ^ Reilly 1992, p. 75.


  • Bachrach, Bernard S. (1993). Fulk Nerra, the Neo-Roman Consul, 987-1040. University of California Press.
  • Dunbabin, Jean (1985). France in the Making: 843-1180. Oxford University Press.
  • Reilly, Bernard F. (1992). The Contest of Christian and Muslim Spain:1031-1157. Cambridge, Mass.: Blackwell. ISBN 9780631199649.

See also[edit]

William VIII, Duke of Aquitaine
Born: c. 1025 Died: 25 September 1086
Preceded by Duke of Gascony
Succeeded by
Preceded by Duke of Aquitaine
Count of Poitiers