Deal Castle is an artillery fort constructed by Henry VIII in Deal, Kent, between 1539 and 1540. It formed part of the King's Device programme to protect against invasion from France and the Holy Roman Empire, and defended the strategically important Downs anchorage off the English coast. Comprising a keep with six inner and outer bastions, the moated stone castle covered 0.85 acres (0.34 ha) and had sixty-six firing positions for artillery. It cost the Crown a total of £27,092 to build the three castles of Deal, Sandown, and Walmer, which lay adjacent to one another along the coast and were connected by earthwork defences.[a] The original invasion threat passed but, during the Second English Civil War of 1648–49, Deal was seized by pro-Royalist insurgents and was only retaken by Parliamentary forces after several months' fighting.

Although it remained armed, Deal was adapted by Sir John Norris and Lord Carrington during the 18th and 19th centuries to form a more suitable private house for the castle's captain, which was by now an honorary position. In 1904, the War Office concluded that the castle no longer had any value either as a defensive site or as a barracks, and it was opened to the public when the captain was not in residence. Early in the Second World War, the captain's quarters were destroyed by German bombing, forcing Deal's captain, William Birdwood, to move to Hampton Court Palace, and the castle became an observation post for an artillery battery placed along the shore line. The castle was not brought back into use as a residence and was restored by the government during the 1950s to form a tourist attraction. In the 21st century, Deal Castle is operated by English Heritage, receiving 25,256 visitors in 2008.

Architecture

Deal Castle retains most of its original 16th-century structure, including a tall keep with six semi-circular bastions, 86 feet (26 m) across, at the centre, flanked by a further six rounded bastions, the western of which served as a gatehouse, surrounded by a moat and a curtain wall. The castle's bastion walls are 15 feet (4.6 m) thick. It was constructed using Kentish ragstone from near Maidstone, locally made bricks, and Caen stone recycled from local monasteries. It was larger than its sister castles at Walmer and Sandown, measuring approximately 234 by 216 feet (71 by 66 m) across and covering 0.85 acres (0.34 ha).

The castle originally had four tiers of artillery – the heaviest and longest-range weapons occupying the upper levels, including the keep – with a total of 66 firing positions, and another 53 gunloops in the basement for handguns, should close defence be required. The embrasures in the walls were all widely splayed to provide the maximum possible space for the guns to operate and traverse, and the interior of the castle was designed with vents to allow the smoke from its guns to escape The battlements on the modern castle are in a faux medieval, rather than Tudor, style and date from 1732.

The historian John Hale considered the original castle to form a transitional design between older medieval English designs and the newer Italian styles of defence. The design of Deal, like its sister castles along the Downs, suffered from design problems: it needed too many guns to ever be fully equipped; its curved surfaces were vulnerable to attack; and despite attempts to keep the walls low and thick, its relatively high profile, driven by the requirement to support several tiers of defences, made it exposed to attack.

Deal Castle is entered through the gatehouse, which originally overlooked a walled garden, since largely destroyed. The dry, stone-lined moat, 20 metres (66 ft) wide and 5 metres (16 ft) deep, would originally have been crossed over a stone causeway and a drawbridge, the latter now replaced by a modern wooden bridge. The gatehouse still has its original iron-studded doors — the historian Jonathan Coad considers them "among the best preserved for their date" – and five murder-holes to enable the garrison to defend the internal passageway with missiles or handguns; it would originally have also been protected by a portcullis at the entrance. The outer bastions were filled with earth in the 1570s, and have 18th-century ramparts; the superstructure around the eastern bastion was rebuilt after the Second World War. A passageway called "the Rounds" runs along the outside of the outer bastions, linking the handgun positions covering the base of the moat.

The keep has a central newel staircase, linking the basement, ground and first floors. When first built, the garrison would have lived on the ground floor of the keep, the first floor being used by the captain, and the basement for stores.The ground floor is subdivided by radial walls and originally would have been further subdivided by partitions; the original ovens and fireplace survive. The first floor mainly dates from the 1720s, although some Tudor elements remain. There is a wooden lantern structure on the top of the keep that contains a bell dating from 1655 and early 18th-century graffiti.The keep's gun embrasures were converted to form sash windows in the 18th and 19th centuries.