Fulk and his brothers Guy, Hugh and Manasses Robert all gave their consent to a privilege their father granted to his monastic foundation of Saint-Médard at Andres in 1084.
[3] In 1117, Fulk and Guy subscribed the privilege in which Manasses founded a monastery dedicated to Saint Leonard in the suburbs of Guînes.
Fulk probably accompanied Counts Eustace III of Boulogne and Robert II of Flanders on the First Crusade in 1096, along with his three brothers and father.
[4] He received the lordship of Beirut after his relative, King Baldwin I of Jerusalem, conquered it, as related in the anonymous short poem, "Verse on the Illustrious Men of the Diocese of Thérouanne who went on the Holy Expedition": Fulk was dead by 1125, when Walter I Brisebarre was Lord of Beirut.
According to Lambert of Ardres he was buried in Palestine: "Fulk, count before Beirut in the promised land [was] there finally buried" (Fulconem in terra promissionis comitem apud Baruth, ibique demum sepultum).