From 1340, English monarchs, beginning with the Plantagenet king Edward III, asserted that they were the rightful kings of France. They fought the Hundred Years' War (1337–1453), in part, to enforce this claim, but ultimately without success. From the early 16th century, the claim had lost any realistic prospect of fulfilment, although every English and, later, British monarch, from Edward III to George III, styled themselves king or queen of France until 1801.
Edward's claim was through his mother, Isabella, sister of the last direct line Capetian king of France, Charles IV. Women were excluded from inheriting the French crown and Edward was Charles's nearest male relative. On Charles's death in 1328, however, the French magnates supported Philip VI, the first king of the House of Valois, a cadet branch of the Capetian dynasty. Philip was Charles's nearest male line relative. French jurists later argued that it was a fundamental law of the kingdom that the crown could not be inherited through the female line. This was supposedly based on the 6th-century Frankish legal code known as the Salic law, although the link to the Salic law, which was tenuous in any case, was not made until the 15th century.