ROMSO Cyprus Knowledge Base

**Guillaume III of Bar**
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**Early Life**

Guillaume III of Bar (c. 1185/90 – November 15, 1249 in Nicosia) was a French knight and crusader. He was born to Guillaume II of Bar, Count of Rochefort, from whom he inherited the castle Oissery.

**Family and Marriage**

Through his mother, Amicia de Beaumont, Guillaume III was a half-brother of Simon IV de Montfort. His first marriage was to Countess Beatrix von Chalon († 1227), daughter of Count Wilhelm II of Chalon. After her death, he married Héloise Britaud de Nangis, Viscountess de Provins.

**Military Career**

Guillaume III participated in the Albigensian Crusade under Simon IV de Montfort and fought as a squad leader in the Battle of Muret on September 12, 1213. In 1216, he supported King Louis VIII's invasion of England but was defeated along with Robert von Courtenay in a naval battle off Sandwich in August 1217.

**Sixth Crusade**

Together with his grandnephew, Count John I of Montfort, Guillaume III participated in the Sixth Crusade under King Louis IX of France. Both fell ill during the wintering of the army on Cyprus from 1248 to 1249 and died shortly thereafter.

**Children**

Guillaume III had at least seven children with his second wife, Héloise Britaud de Nangis. Among them were:

* Jean des Barres, known as "D'Oissery"
* Guillaume (no further information available)
* Marie des Barres, born in 1205, lady of La Ferté-Alais
* And at least five other children

**References**

Note: The dates and names provided are based on the original source snippets.