In 1337 Phillip confiscated Aquitaine and Ponthieu from Edward alleging he was harbouring Phillip's fugitive cousin and enemy, Robert of Artois. In response, Edward proclaimed himself king of France to encourage the Flemish to rise in open rebellion against the French king. The conflict, later known as the Hundred Years' War, included a significant English naval victory at the Battle of Sluys, and a victory on land at Crécy, leaving Edward free to capture the important port of Calais. A subsequent victory against Scotland at the Battle of Neville's Cross resulted in the capture of David II and reduced the threat from Scotland. The Black Death brought a halt to Edward's campaigns by killing perhaps a third of his subjects. The only Plantagenet known to have died from the Black Death was Edward III's daughter Joan in Bordeaux.