A Tudor artillery castle and martello tower known as Sandgate Castle, 124m south-west of St Paul’s Church
Reasons for Designation
Sandgate Castle was built as an artillery castle by Henry VIII but was altered to form a Martello tower in the early 19th century. Artillery castles were constructed as strong stone defensive structures specifically to house heavy guns. Most date from the period of Henry VIII's maritime defence programme between 1539 and 1545, though the earliest and latest examples date from 1481 and 1561 respectively. They were usually sited to protect a harbour entrance, anchorage or similar feature. These monuments represent some of the earliest structures built exclusively for the new use of artillery in warfare and can be attributed to a relatively short time span in English history. Their architecture is specific in terms of date and function and represents an important aspect of the development of defensive structures generally. Although documentary sources suggest that 36 examples originally existed, all on the east, south and south east coasts of England, only 21 survive. All examples are considered to be of national importance.
Martello towers are gun towers constructed to defend the vulnerable south eastern coast of England against the threat of ship-borne invasion by Napoleonic forces. Built as a systematic chain of defence in two phases, between 1805-1810 along the coasts of East Sussex and Kent, and between 1808-1812 along the coasts of Essex and Suffolk, the design of martello towers was based on a fortified tower at Mortella Point in Corsica which had put up a prolonged resistance to British forces in 1793. The towers take the form of compact, free-standing circular buildings on three levels built of rendered brick. The ground floor was used for storage, with accommodation for the garrison provided on the first floor, and the main gun platform on the roof. As the expected Napoleonic invasion attempt did not materialise, the defensive strength of the martello tower system was never tested, and the tower design was soon rendered obsolete by new developments in heavy artillery. Many were abandoned and fell into decay or were demolished although a few saw use as look out points or gun emplacements during the two World Wars.
Despite later alterations and damage, the Tudor artillery castle and martello tower known as Sandgate Castle survives well. The castle is well recorded in documentary sources, such as building accounts, which increases our understanding of the site and enhances its importance. It is a unique example of a Henrician fortification built not to defend a harbour or anchorage but to protect the beach and coast road of this part of Kent. The conversion of the castle into a Martello tower is unusual and, along with its use during the Second World War, adds to its interest as a site of continued strategic significance. It is testament to the provisions carried out to defend England from some of the most serious invasion threats of the country’s history.
This record was the subject of a minor enhancement on 19 June 2014. The record has been generated from an "old county number" (OCN) scheduling record. These are monuments that were not reviewed under the Monuments Protection Programme and are some of our oldest designation records.
The monument includes a Tudor artillery castle and later martello tower surviving as upstanding and buried remains. It is situated on the sea front, south of Castle Road at Sandgate.
The artillery castle was built by Henry VIII and includes a two-storey circular central tower or keep surrounded by two curtain walls surviving as upstanding remains. The southern upstanding part of the castle has been largely destroyed but will survive as buried remains including foundations. The inner curtain wall originally formed a triangular ward and had three round towers. The two northern towers are visible as upstanding remains; that to the north-east surviving most intact. The outer curtain wall also formed a triangular ward and has rounded corner projections and convex walls between them. On the northern side is a semi-circular gatehouse connected to the curtain wall by a rectangular passage, the doorway to which is hidden in the back wall. The castle rises progressively towards the centre to provide several tiers of heavy guns. The guns would have been positioned behind the embrasures or gun-ports, although local defence was also provided through numerous gun-loops for hand guns. The castle was heavily altered and partly rebuilt in the early 19th century. The tops of the towers were reduced and the central keep or tower, which originally contained three stories, was reduced to two stories high and converted into a Martello tower. The rubble was used to fill the outer ward of the castle to form an esplanade. The site was refortified with pillboxes during the Second World War. The remains of these pillboxes are included in the scheduling.
Sandgate Castle was built as part of a chain of coastal defences by Henry VIII. The castle is well recorded in documentary sources and full building accounts survive from the Tudor period. It was constructed in 1539-40 to the design of Stefan von Haschenperg. The castle is unusual in that it was not used to defend a harbour or anchorage but instead commanded the beach and coast road to Dover. In 1557 the floors and roofs were renewed and by 1616 a large gun platform for ten cannon had replaced the southern bastion. In 1715-16 the keep was re-roofed and the seaward battery rebuilt following damage by the spring tides. In 1805 it was brought into the scheme to defend the coasts with Martello towers against the threat of Napoleonic Invasion. Eight guns were mounted on the seaward side of the outer curtain and a single 24 pounder gun was mounted on the roof of the keep. A large magazine was built under the esplanade to the south of the gatehouse. The site was partially excavated in 1976-9 as part of a restoration programme.
The upstanding remains are Grade I listed.