Alfonso of Brienne

Alfonso of Brienne, called Alphonse d'Acre , was the son of John of Brienne and Berengaria of León, born in Acre.
Alfonso took part in the Seventh Crusade as a squire. By his marriage to Marie, Countess of Eu he became Count of Eu. He was also Grand [Chamberlain of France]. He died on 14 September 1270 in Tunis on the Eighth Crusade in the same epidemic that claimed King Louis IX.
He had at least two children by Marie:

John I of Brienne, [Count of Eu]
Blanche, Abbess of Maubuisson