Marie, Countess of Ponthieu Countess suo jure of Ponthieu and Montreuil (1199–1250) Parents Alys, Countess of the Vexin William IV, Count of Ponthieu Children Philippa of Dammartin Mathilde de Dammartin Marie de Dammartin Joan, Countess of Ponthieu Agathe de Dammartin Siblings daughter d'Anjou Partners Simon, Count of Ponthieu Matthieu de Montmorency, Comte de Ponthieu, Sire de Attichy
