 He was succeeded in Navarre by his niece Joan II and in France by his paternal first cousin Philip of Valois.However, the dispute on the succession to the French throne between the Valois monarchs descended in male line from Charles's grandfather Philip III of France, and the English monarchs descended from Charles's sister Isabella, was a factor of the Hundred Years' War.By virtue of the birthright of his mother, Joan I of Navarre, Charles claimed the title Charles I, King of Navarre.