Guillaume III DE DAMPIERRE Seigneur de Dampierre, Comte de Flandres

   Research Notes:

The Genealogica Comitum Flandriĉ Bertiniana names (in order) "Guillelmum Guodnem et Iohannem" as the three sons of "Guillelmo domino de Dampetra [et] Margaretĉ", specifying that "primo mortuo sine liberis in tornramento apud Trasegnies". His parentage is specified by Matthew of Paris.

He succeeded his father in 1231 as Seigneur de Dampierre. Seigneur de Courtrai. After his mother succeeded as Ctss of Flanders in 1244, his half-brother Jean d'Avesnes claimed his inheritance. Louis IX King of France ruled in 1246 that Hainaut should be given to Jean d'Avesnes while Guillaume de Dampierre should inherit Flanders, thereby succeeding as GUILLAUME III Count of Flanders, ruling jointly with his mother. Willem II Count of Holland, as king of Germany, received homage from Guillaume de Dampierre for imperial Flanders in 1248.

Guillaume III died from injuries received during a tournament, his mother suspecting that the allies of the Avesnes family of Hainaut were responsible. The Annales Blandinienses record the death in 1251 of "Willelmus comes Flandrie" and his burial at "Market". The Necrologio Sanctĉ Waldetrudis records the death "III Non Mai" of "Willermi comitis Flandrie".

   Marriage Information:

Guillaume married Beatrice DE BRABANT, daughter of Henri II 'The Courageous' DE BRABANT Duc de Brabant and Maria VON HOHENSTAUFEN Princess of Germany, in Nov 1247 in Louvain, Belgium. (Beatrice DE BRABANT was born about 1225 and died on 11 Nov 1288.)