The widow of Charles IV gave birth to a daughter. Isabella of France, sister of Charles IV, claimed the throne for her son, Edward III of England. The French rejected the claim, noting that "Women cannot transmit a right which they do not possess", a corollary to the succession principle in 1316. The regent, Philip of Valois, became Philip VI of France in 1328. Philip became king without serious opposition, until his attempt to confiscate Gascony in 1337 made Edward III press his claim to the French throne.