The continuing decline of the confederation of the Cinque Ports may be ascribed to a variety of different circumstances. While they survived the raids from the Danes and the French, the numerous destructive impact of plagues, and the politics of the 13th-century Plantagenets and the subsequent War of the Roses, natural causes such as the silting of harbours and the withdrawal of the sea did much to undermine them. The rise of Southampton, and the need for larger ships than could be crewed by the 21-man service of the ports, also contributed to the decline.