MARY DE ST POL COUNTESS OF PEMBROKE, BARONESS OF WEXFORD IN IRELAND, AND OF MONTIGNAC, BELLAC AND RANÇON IN FRANCE, was the daughter of Guy, Count of St Pol in the Pas-de-Calais, head of the younger branch of the great French house of Châtillon of Châtillon-sur-Marne. During the Middle Ages this family numbered among its great men Constables of France, Cardinals, a Pope who was canonised and another Saint, St Charles of Blois, a cousin of Mary de St Pol, and no family during the thirteenth and fourteenth centuries married more often into the royal line than the family of Châtillon. Their arms were gules, three pales vair with a chief or, and this coat was said to have been granted to a warrior of the family who was one of a party of Crusaders surprised by the Turks when they had neither banners nor blazons. They therefore cut up the scarlet cloaks lined with fur which they were wearing, and displayed these strips instead of banners and coats of arms. Having achieved victory they all vowed that they would never display any heraldry in future other than gules and vair. This legend is however discredited by Andre Duchesne, the seventeenth-century historian of the Maison de Chastillon. The father of Guy de St Pol had added to these arms, “for difference”, a label of five points azure. Guy de St Pol married Mary of Brittany, who was the daughter of John de Dreux, Duke of Brittany, and Beatrice daughter of King Henry III of England.