In 1340, soon after the outbreak of the Hundred Years' War, Edward III proclaimed himself King of France and quartered the arms of France with those of England, as shown here on his seal. France is represented by fleurs de lis, England by lions.
A dispute over the succession to the French throne was one of the prime causes of the Wars of the Roses. In 1328, Charles IV of France died without leaving a male heir. His two possible successors were Philip of Valois, the nearest direct male relative, and Edward III of England, who was the son of Charles's sister and therefore the closest blood relative. Under French law, however, women were unable to succeed to the French throne. Although Edward's envoys argued that women were able to transmit the right to their male offspring, the French nobility decided in favour of Philip. When war broke out in 1337, however, Edward chose to pursue his claim to be King of France.