The
County of Ponthieu, centered on the mouth of the
Somme, became a member of the Norman group of vassal states when Count Guy submitted to William of Normandy after the
battle of Mortemer. It eventually formed part of the dowry of
Eleanor of Castile and passed to the English crown. Much fought-over in the
Hundred Years' War, it eventually passed to the French
royal domain, and the title
Count of Ponthieu became a courtesy title for the royal family.