Upnor Castle

Has been described as a Certain Artillery Fort, and also as a Certain Chain Tower

There are major building remains

NameUpnor Castle
Alternative NamesUpnore
Historic CountryKent
Modern AuthorityMedway
1974 AuthorityKent
Civil ParishFrindsbury Extra

The development and history of Upnor castle is well documented by surviving construction drawings, building accounts and contemporary records. It was the last artillery castle to be built in England and its design differs markedly from that of earlier examples. The castle survives well in the form of standing remains and earthworks, and the detailed interpretation of these has increased our knowledge of both the original form and strategic importance of the castle, and its subsequent remodellings and changing use over the years. Its close association with the naval dockyards at Chatham provides evidence for the importance of the Medway for naval defence from the Elizabethan period. The monument includes an artillery castle situated on the north western bank of the River Medway. The castle survives in the form of standing buildings and ruined structures, Listed Grade I, and earthworks. It was built in two main phases, initially between 1559 and 1567 to a design by Sir Richard Lee, in order to provide increased protection for Queen Elizabeth I's warships, most of which were anchored when out of commission in the sheltered Medway estuary at the nearby, newly established dockyards at Chatham. The second phase of construction, dating to the years between 1599 and 1601, aimed mainly to improve the landward defences of the castle. The castle also shows signs of later remodelling and repair. The castle is constructed of ragstone faced with coursed ashlar blocks, along with some red brick. Much of the masonry was imported from earlier, derelict buildings demolished for the purpose at Rochester Castle, Aylesford and Bopley. Additional stone was transported from quarries at Bocton. Its defences are largely orientated towards the river and range around a north east to south west aligned, two-storeyed rectangular block measuring 41m by 21m

This originally provided accommodation for the garrison, and has a frontage which includes a central, polygonal bay containing a circular staircase, and circular turrets with garderobes, or latrines, projecting from either end. The facade is pierced by original doorways with four-centred heads at ground floor level and by bulls-eye and round headed windows with classical mouldings, inserted during the 18th century, on the first floor. Projecting out over the river from the main building is a low, triangular, open gun platform, known as the water-bastion, which originally housed most of the castle's heavy artillery, now represented by six 19th century guns mounted on their original wooden carriages. The water-bastion receives additional protection from a continually renewed, staked palisade, originally erected in 1600. To the north east and south west are two square, flanking towers linked to the main building by a crenellated curtain wall. These are fronted by semicircular stair turrets which incorporate splayed gun embrasures at first floor level. To the north west the main building is backed by a rectangular courtyard bounded by a stone built curtain wall topped with brick coping. This enclosing wall was largely rebuilt, after being allowed to fall into disrepair, during the 17th century, and is now around 1m thick and c.4m high. Running along the inside of the curtain wall are the brick foundations of now ruined, narrow lean-to buildings, also dating to the 17th century, which were originally used for storage. In the north western corner is a sallyport, with a later inserted oven beside it. The castle's well is situated within the north western quarter of the courtyard. The castle buildings are entered by way of a centrally positioned, four-storeyed gatehouse in the north western side of the curtain wall. This has a central, round-headed gateway, above which is an inserted, late 18th century clock, leading into a wide entrance passage. Flanking the gateway on its inner side are two tall, rectangular corner towers. Gun embrasures pierce the walls of the gatehouse and provide further protection for the entrance. The gatehouse was remodelled during the early 1650's, and heightened in brick after a fire caused substantial damage in 1653. It is now capped by an early 19th century wooden bellcote and modern flagpole. The castle is enclosed on the landward side by a substantial dry ditch, originally 9.8m wide and 5.5m deep, which has become partially infilled over the years. This was originally spanned by a drawbridge, although this no longer survives. By 1588, the year of the Spanish Armada, the castle's garrison included six gunners and a master gunner, and in 1603 it is recorded as housing 19 heavy guns. The castle did not see action until June 1667 when, during the Second Dutch War, an enemy navy squadron under de Ruyter launched a successful surprise attack on the Thames and Medway defences. The squadron broke through the chain boom-defence which had been positioned across the river between Hoo Ness and Gillingham and threatened Chatham dockyard. Much English shipping was destroyed before a hastily organised defence at Upnor stalled the Dutch attack. This episode provoked a radical revision of south eastern coastal defences and the building of new forts along the Medway. These reduced the strategic importance of the by now old fashioned castle and in 1668 it was converted into a magazine and naval storage depot. The depot buildings gradually extended into the area to the north east of the monument which is still used by the Ministry of Defence, disturbing and overlying earlier gun emplacements associated with the castle. The earthwork remains of these are thought to be represented within the monument by a broad bank around 14m wide running parallel with the river from the ground immediately to the north east of the castle towards the adjoining naval depot to the north east. During the 18th century, the castle's accommodation was extended by the construction of a new barracks block and associated storage buildings on land immediately to the south west of the monument. The castle and its depot continued to supply munitions to the navy until 1827, when it was fitted out as an ordnance laboratory. In 1891 responsibilty for the administration of the castle was transferred from the War Office to the Admiralty, and the newly created Naval Armament Supply Department began to use it, amongst other things, as a proofyard. The castle served as part of the Magazine Establishment during World War II, and in 1941 was partially damaged by two bombs which fell in the garden of nearby Upnor House. After 1945 the castle went out of military use and was opened to the public. Upnor Castle continues to form part of the Crown Estate and is now in the care of the Secretary of State. (Scheduling Report)

Fort. 1559-67 to designs by Sir Richard Lee, enlarged 1599-1601 to designs by Arthur Gregory and an Italian engineer surnamed Baptist. Converted into magazine 1668, Ordnance Laboratory 1827 and part of the Naval Armament Supply Department in the late C19. Coursed ragstone with some red brick heightening and patching. Rectangular main block with water bastion and river frontage belongs to Sir Richard Lee's design of 1559-67. Two riverside towers substantially rebuilt and gatehouse, curtain wall and moat added 1599-1601. River front height- ened, alterations to gatehouse and towers later in C17. Gatehouse: coursed coarse ragstone walls either side of entrance with cross-loops, one marked on lintel 'W. Webster XXIII Regt, 1787 May'. Coursed rubble gatehouse projecting from two wider taller rear towers, all brought up to greater height in C17 with double-splayed segment- headed stone-dressed gun-ports in top stage of sides of gatehouse. Wooden bell-cote over gatehouse with bell dated 1809. Recess immed- iately over gate-arch, perhaps for coat-of-arms. Round-arched inner gateway in line with inner tower walls with C20 balustrades on two floors over, following C18 configuration. Curtain wall: rebuilt after 1625. Coursed ragstone with red brick parapet and wooden stakes projecting over moat to north-west and south-west. Magazine: East side: Coursed ragstone with some red brick rebuilding. Main block in centre with north and south towers attached by lower walls at level of band on main block. Staked palisade projecting to east into River Medway in triangle full-width of block with inner gun-embrasured water bastion full width of magazine only. North-east and south-east towers: Rectangular with brick parapets and round stair-towers towards Medway. Various irregular loops and wooden mullioned windows. Magazine block: Platband at half-height and crenellated parapet. End projecting round towers and central projecting octagonal stair tower, all taller than block which has recessed ends behind shallow splayed side to centre. 4 oculi on two upper floors and 2 round-arched windows on stair-tower, all added before 1698. Various other loops. 3 round-arched doorways at water bastion level, one in centre to wooden spiral stair, two outer doorways to small side compartments under magazine. At the height of its use in the early C17 the Castle was equipped with 'a demi-cannon, 7 culverin, 5 demi-culverin, a minion, a falcon, a saker and 4 fowlers with 2 chambers apiece'. (Listed Building Report)

This site is a scheduled monument protected by law

This is a Grade 1 listed building protected by law

Historic England Scheduled Monument Number
Historic England Listed Building number(s)
Images Of England
Historic England (PastScape) Defra or Monument number(s)
County Historic Environment Record
OS Map Grid ReferenceTQ758705
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Copyright Paul Gillett and licensed for reuse under this Creative Commons license.
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved
Photo by Philip Davis All Rights Reserved

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  • Mackenzie, J.D., 1896, Castles of England; their story and structure (New York: Macmillan) Vol. 1 p. 53-5 online copy
  • Hasted, Edward, 1797 (2edn), The history and topographical survey of the county of Kent Vol. 3 p. 525- online transcription
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  • Saunders, A.D., 1970, 'Walmer Castle; Deal Castle; St Augustine's abbey, the monastic buildings; Upnor Castle' The Archaeological Journal Vol. 126 p. 276-8
  • O'Neil, B.H.St.J., and Evans, S., 1952, 'Upnor Castle, Kent' Archaeologia Cantiana Vol. 65 p. 1-11 online copy

Guide Books

  • 2001, Upnor Castle Kent (London: English Heritage)
  • Saunders, A.D., 1985, Upnor Castle, Kent (London: English Heritage)
  • Saunders, A.D., 1967, Upnor Castle, Kent (HMSO)

Primary Sources

  • Lemon, R. (ed), 1856, Calendar of State Papers, Domestic Series 1547-1580 (London: Longman) p. 172 online copy
  • Lemon, R. (ed), 1865, Calendar of State Papers, Domestic Series 1581-1590 (London: Longman) p. 304 online copy (order for 'a great chain of iron)


  • Saunders, A. and Smith, V., 2001, Kent's Defence Heritage Gazetteer (Kent County Council) Part 1: KD12