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