Description from record TQ 76 NW 68 :
(TQ 7390 6768) Fort Clarence [NAT] (1)
TQ 739 677 Fort Clarence, Rochester. (2)
With its associated works, Fort Clarence forms a promontory fortress stretching from the Medway to the Maidstone Road, enclosing Rochester. It consisted of a flat-bottomed ditch, 40 feet wide and 30 feet deep. In the centre of the line is the great brick keep, 60 feet high, known as Fort Clarence. Pentagonal in plan, three storeys high, it was designed to house three tiers of guns firing to enfilade the ditch. To the W side of the fort was a brick archway across the Borstal Road, it was demolished in 1924 to widen the road. Cross fire to the angles of the ditch was provided by two smaller forts. These forts, except that on the Maidstone Road, had an elaborate network of underground galleries and magazines and two complicated sally ports. The fort was completed in 1810, the ditch and terminal forts by 1812 and the whole line virtually completed by 1815. It was considered obsolete even before it was finished, and by the 1830's was being used as a military hospital and later as a prison. Successive demolitions and the filling in of the greater part of the ditch have left only the brick keep of Fort Clarence (see plan). It is in a derelict condition. Scheduled. (3,4)
A personal communication resulting from a watching brief reported the location of a brick wall running roughly north south to the south side of the fort. The wall is constructed of nineteenth century bricks and loam mortar it is faced on its east side with loose flints.(5)

Evaluation work in August 2000 located part of the inner wall of the barrier ditch. Trenches placed to locate the remains of the Western Warders Quarters and the Cellblock found no evidence of these structures as this area had been severely truncated by the building of a GPO Deport in the 1960's.(12)

Watching Brief in May 2001 recorded the northern and south western walls of the Maidstone Road Guardhouse and part of a concrete floor. Further structures identified included a demi-vaulted chamber (ablution chamber), the front wall of the guardhouse, the ditch revetment wall and other flooring areas. (13)

Additional Info (6, 7, 8, 9, 10, 11).

Fort Clarence was one of several new detached works, built in the Napoleonic period to provide advance defences for the dockyard and to deny the cross-Medway bridge at Rochester to the enemy. The other works were, Fort Pitt (TQ 76 NE 84) and the Delce (TQ 76 NW 366) and Gibraltar (TQ 76 NE 348) Towers that flanked Fort Pitt [14].

The following text is from the original listed building designation:
ROCHESTER BORSTAL ROAD TQ 76 NW 2/13 Fort Clarence (formerly listed under S t Margaret's Street) 19.2.70 II Fort, forming part of the anti-Napoleonic defences of the Medway towns. 1812. Stock brick with limestone dressings. Surrounded (where not infilled) by deep revetted ditch. 3 storeys with basement. Corner circular turrets with moulded limestone cornice bands. Three massive stylized mahicoulis, also limestone, to road (entrance) side only. Otherwise plan brick with reliving arches over the 2 levels of deep embasures, mostly with very shallow arches although those to entrance front round-headed. Interior not inspected, and plan and internal arrangement not known.
Listing NGR: TQ7345967115 (15)

Peter Kendall, 2006, Historic barracks in Medway (Unpublished document). SKE15939.

<01> OS 1:10000 1975 (OS Card Reference). SKE48160.

<02> DOE(IAM) AMs Eng 2 1978 112 (OS Card Reference). SKE41414.

<03> DOE(IAM) Rec Form plan (OS Card Reference). SKE41429.

<04> The Medway Forts 1976 (KR Gulvin) 10,11 (OS Card Reference). SKE50415.

<05> Handbook of Kent's Defences 1540-1945 1977 (D Bennett) 10-14 (OS Card Reference). SKE43670.

<06> Kent Arch Rev 53 1978 53-7 plan (OS Card Reference). SKE45789.

<07> Untitled Source, pers. comm. Peter Dawson to KCC 27.03.97 (Unpublished document). SKE6451.

<08> Lower Medway Archaeological Research Group, 1997, Watching Brief at Fort Clarence, Rochester (Unpublished document). SKE7224.

<09> Essex County Council Field Archaeology Unit, 2000, Fort Clarence St Margaret's Street Rochester Kent Archaeological Desk-based Assessment Revision 0 (Unpublished document). SKE7443.

<10> Essex County Council Field Archaeology Unit, 2000, Fort Clarence, St. Margaret's Street, Rochester, Kent. Archaeological Evaluation, Revision 1. (Unpublished document). SKE7675.

<11> Essex County Council Field Archaeology Unit, 2000, Fort Clarence, Desk-Based Assessment (Unpublished document). SKE7732.

<12> Essex County Council Field Archaeology Unit, 2000, Fort Clarence, St Margaret's Street, Rochester, Kent: Archaeological Evaluation (Unpublished document). SKE7733.

<13> English Heritage, 2001, Fort Clarence, Rochester, Kent: Napoleonic gun tower and defensive line (Unpublished document). SKE54045.

<13> Essex County Council Field Archaeology Unit, 2001, Watching Brief at Fort Clarence Maidstone Road Guardhouse, St Margaret's Street Rochester (Unpublished document). SKE7734.

<14> Victor Smith and Ron Crowdy, 1994, From Tudor Rose to Mushroom Cloud. The Gazetter of Defence Heritage Sites in the Kentish Part of the Thames Gateway. An Overview (Unpublished document). SKE12458.

<15> English Heritage, List of Buildings of Special Architectural or Historic Interest (Map). SKE16160.