Walmer Castle against Charles' brother, King James II, the townsfolk of Deal seized Walmer Castle on behalf of William III, the Prince of Orange. By the end of the century, however, the castle was increasingly regarded as out of date from a military perspective. In the 18th century, Walmer Castle became the official residence of the Lord Warden of the Cinque Ports. The Lord Warden was originally a medieval title linked to five key ports along the coast of England; the position's prominence had faded, but it still retained important judicial and military functions. When Lionel Sackville, the Duke of Dorset, was
Device Forts demolishing much of the keep and adding residential wings and gardens over the landward defences, and Brownsea Castle began to be converted into a country house from the 1720s onwards. Walmer became the official residence of the Lord Warden of the Cinque Ports, and Lionel Sackville, the Duke of Dorset, carried out extensive work there after 1708. There was probably some rivalry between Sackville and the naval officer Sir John Norris, who redeveloped nearby Deal Castle during the same period, creating comfortable wood-panelled quarters for himself there overlooking the sea. Criticisms were levelled at the defences of the Device Forts,