 The French king Philip Augustus had seized Normandy from King John of England as recently as 1205, and Philip's heirs could not risk the English monarchy recovering any land in that area, since it might allow the Plantagenets to re-establish control in Normandy.As it happened, Joan's father Simon had become involved in a conspiracy of northern French noblemen against Philip Augustus and to win pardon from Philip's son King Louis VIII, Simon—who had only daughters—was compelled to promise that he would marry off neither of his two eldest daughters without the permission of the king of France.In 1235, Queen Blanche invoked that promise on behalf of her minor son, King Louis IX, and threatened to deprive Simon of all his lands if Joan married Henry III.