Following the death of Charles IV of France in 1328, Philip, Count of Valois, had been chosen as his successor and crowned King Philip VI of France, superseding his closest male relative Edward III of England through the ancient tradition of Salic Law, whereby Kingship could not be inherited through any maternal line, and thus adhering to agnatic succession. Edward had been reluctant to pay homage to Philip in his role as Duke of Aquitaine, resulting in Philip's confiscation of those lands in 1337, an act which provoked war between the two nations. Three years later, Edward declared himself King of France. The war had begun well for the English. They had achieved naval domination early in the conflict at the Battle of Sluys in 1340, devastated the south west of France during the Gascon campaign of 1345 and Lancaster's chevauchée the following year, inflicted a severe defeat on the French army at Crécy in 1346, and captured Calais in 1347.