Walmer Castle dates from the 16th century, and forms part of a line of defence along the edge of the Downs. As a result of constant threats of invasion from Spain, Henry VIII ordered castles to be built at Walmer, Deal and Sandown, with a series of defence works and ditches located between them. This allowed for defending any coastal attack, while at the same time commanding the Downs.
Unlike castles of an earlier medieval date, Walmer Castle has no high walls for protection. As with Deal and Sandown (now only foundations), Walmer Castle was built at a relatively low level to take account of the changing design of fortification in line with current modes of attack. Gunpowder was becoming more widely used and high walls would only have provided a greater target area for attack. With low outer walls, reinforced with solid bastions, and the added protection of earth ramparts and moats, there was less of a target for enemy fire but plenty of strength to withstand a battering.
The concentric plan of Walmer Castle was typical of Henry VIII's castles being built of stone and brick, with a circular keep located at its centre. Surrounding the keep is a circular curtain wall with four, almost circular, bastions projecting from it. Access to Walmer Castle was via a bridge and drawbridge at the northern bastion, which acted as the castle's gatehouse. Running around Walmer Castle at basement level, a gallery provided gun loops for defence, with a further three levels of gun positions above that.
By the time Walmer Castle was completed, the threat of invasion had subsided, and a small garrison were housed within the central keep. Although built during a period when luxury was an important feature of any residence, the accommodation at Walmer Castle was quite basic and practical, its main purpose being that of an artillery garrison.
From the early 18th century, Walmer Castle has served as the official residence of the Lords Warden of the Cinque Ports, and subsequently lost its military influence in terms of its function and décor. The individual style and requirements of successive wardens have somewhat softened the appearance of the harsh, military fortress that Walmer Castle once stood as. Two wardens in particular, William Pitt and the second Earl of Granville, had a significant impact on Walmer Castle in that they were largely responsible for the gardens that have served to enhance the natural beauty of Walmer Castle's location. Other notable wardens include the Duke of Wellington, who died at Walmer Castle, and his sparse bedroom has been left moreorless as it was from that time. Until her recent death, the Queen Mother was the last Lord Warden and she often enjoyed a stay at Walmer Castle during the summer. Some of the rooms used by her are now open to the public.
With such a rich diversity of individual influences, Walmer Castle is a fascinating place set in beautiful gardens - very different from the original design and purpose for which Henry VIII saw it.