In whose reign did the Hundred Years War begin?

The beginning of the Anglo-French War, later called the Hundred Years, falls on the year 1337. After the French king Charles the Fourth, who had no sons, died (and women could not take the throne, only men had the right to do so), Charles’ cousin, Philip the Sixth de Valois, put on the French crown. King Edward III of England expressed his disagreement with this, believing that he himself, being Charles’s nephew, may well become king of France.