One cause of the Hundred Years' War was the English claim to the French throne. The war lasted from 1337 to 1453, and it was a series of conflicts fought between the Kingdom of England and the Kingdom of France, as well as their various allies and vassals. The English claim to the French throne was based on the fact that King Edward III of England was the nephew of the French king, and he believed that he had a legitimate claim to the French crown. The French, however, rejected Edward's claim, which led to a long and bloody conflict between the two nations.