William III (1224 –
6 June 1251) was the lord of
Dampierre from 1231 and
count of Flanders from 1247 until his death. He was the son of
William II of Dampierre and
Margaret II of Flanders.
Margaret inherited Flanders and
Hainault in 1244 and immediately the
War of the Succession of Flanders and Hainault began between William and his brothers, the Dampierre claimants, and the children of Margaret's first marriage to
Bouchard of Avesnes. Margaret favoured William and declared him her heir. In 1246,
Louis IX of France intervened to arbitrate the conflict and declared Flanders to William and Hainault to
John I of Avesnes. Margaret officially invested William as count in 1247 and he is known, as count, as "Willem (or Guillaume) II."
In November of that year, William married Beatrice, daughter of
Henry II, Duke of Brabant and
Marie of Hohenstaufen. They had no children. Meanwhile the fight continued over
Namur between the Dampierres and the Avesnes. On
19 May 1250, peace was signed. On 6 June the next year, William was assassinated at a
tournament in
Trazegnies by a group of knights financed by Avesnes. The war began anew with
Guy, William's younger brother, taking up Flanders and the Dampierre claim.
William IIICategory:Counts of FlandersCategory:1224 birthsCategory:1251 deathsCategory:Assassinated royaltyde:Wilhelm II. (Flandern)fr:Guillaume III de Dampierrenl:Willem II van Vlaanderenpl:Wilhelm III de Dampierre
