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 By the end of the century, however, the castle was increasingly regarded as out of date from a military perspective.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
Cinque Ports Fortress Royal Engineers Fourth Army by the time of the Armistice, while 547 Company moved to VI Corps in September and to Third Army by November 1918. 546th and 547th Army Field Companies were disbanded in France on 4 June 1919 and 1 May 1919 respectively. When the TF was constituted as the Territorial Army in the 1920s, the Cinque Ports (Fortress) RE was reformed as three Lights Companies, forming part of the Coast Defence Troops in 44th (Home Counties) Divisional Area. During World War II the Cinque Ports Fortress RE once again provided a field unit: 579 Army Field Company, formed in