Having failed to produce a son that survived infancy, Philip was succeeded by his brother (and the youngest of Philip IV's sons) Charles IV (1322–1328). The new king faced much of the same problems as his predecessors (namely the quarrels over Flanders and Gascony). Having put an end to the chaos in southern France that his brother faced, he turned his attention to Flanders, but then a revolt broke out in Gascony over the unwelcome construction of a fortress on the border by a French vassal. The king's uncle Charles of Valois invaded the province, whereupon the former declared Edward II's claims to it null and void. Although Charles IV's sister married the English king, he still refused to return Gascony and finally came to an agreement to divide it up among the two rulers.