Alfonso of Brienne

Alfonso of Brienne, called Alphonse d'Acre (c. 1227–1270), was the eldest son of John of Brienne, king of Jerusalem and Latin emperor of Constantinople, and Berengaria of León, born at Acre. He spent his career at the court of Louis IX. By marrying Marie of Exoudun, heiress of Eu, he became count of Eu and served as Grand Chamberlain of France.

In 1258 he represented Louis in negotiations with Henry III of England's envoys for the Treaty of Paris. Widowed in 1260, he governed Eu for his young son.

In 1265 he aided Alfonso X of Castile against the Moors. He joined the Eighth Crusade and died of dysentery at Tunis on 25 August 1270, the same day as Louis IX.