Monument MPM1758 - King's Bastion

Bastion to the former fortifications of the town of Portsmouth. The bastion was originally built during the late-16th century, and was remodelled during the 17th and 18th centuries. An earlier fortification stood on the site from the late-14th century. The bastion was originally known as Green's Bulwark and later Wimbledon's Bastion. It was renamed King's Bastion after George III.

Together with Long Curtain and Spur Redoubt, King's Bastion forms part of the only section of ramparts and moat which enclosed the town of Portsmouth to survive above ground. The bastion is made up of four sides, with two short flanks and two longer diagonal sides which form an apex. The side walls are constructed from stone, with a low brick parapet wall and the top of the monument is banked and grassed [1]. The stone-built revetment wall which now forms the north-east end of the moat is a modern construction [4]. The remains of a traversing-gun position survive at the southeast corner of the bastion.

A fortification had stood on the site of King's Bastion since the first town defences, consisting of a simple earthwork and moat, were constructed during the late-14th century [2]. The bastion appears as a small tower on early maps/plans, and was originally known as Green's Bulwark. It was rebuilt in stone when the defences were remodelled by Popynjay in 1584. During the 17th century the name was changed to Wimbledon's Bastion after Viscount Wimbledon who was Governor of Portsmouth 1630-38. The bastion was modified by de Gomme in the late-17th century, and a map dated 1700 shows a raised platform with two tiers of guns to give added fire power to the flanks. Further alterations were carried out in 1730 and the bastion was later renamed King's Bastion after George III [3]. The bastion appears to have been used as the flag base of the fortress from at least the 18th century [2].


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An archaeological evaluation of the turf-covered remains of King's bastion undertaken by Portsmouth Museum Service in 1992 revealed some surviving features. Four trenches were excavated at strategic points of the bastion to allow the recovery of information without disrupting any existing structural features.

The core of the bastion was found to survive below modern levelling material at approximately the original terre-plein level (surface of the rampart) in several trenches. This consisted of a clean yellow-orange gravel fill with a variable mixed amount of dark brown soil.

A substantial section of red-brick wall was revealed 0.2m below the modern turf line near to the western flank of the bastion. The wall measured 0.35m in thickness and 0.70 high. It had been constructed directly onto the underlying gravel. It was thought that a 'visible vegetation mark' may indicate the survival of a 20m length of the same wall beneath the modern top soil and turf.

A substantial limestone wall which had once formed the north-east scarp revetment of the fausse-braye and wall of the moat, was revealed in an area to the northeast of the main bastion work (see MPM1962).

The evaluation report notes that investigations at King's Bastion had shown that the superstructure was demolished and the top of the earthwork levelled at approximately terre-plein level, the only exception being a traversing-gun position at the apex of the bastion. All structures beyond the northeast flank had been levelled and the moat infilled. There is a mid-20th century footpath which crosses the Bastion to a gun position.

[4]

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Gravel rich deposits beneath modern made ground were observed during a watching brief in 2019 in trenches adjacent to King's Bastion on the north-eastern side. The deposits were thought to have either represented in situ construction material from an earlier form of the bastion earthwork which appeared to be shown extending further to the north-east on 17th and 18th century maps, or eroded material from the bank of the extant bastion.



[5]

<1> Historic England, The National Heritage List for England (Index). SPM35.

<2> Corney, A, 1973, Fortifications in Old Portsmouth - A Guide (Bibliographic reference). SPM388.

<3> Patterson, B.H., 1987, A Military Heritage A History of Portsmouth & Portsea Town Fortifications (Bibliographic reference). SPM43.

<4> Fox, R, 1992, Archaeology in Hampshire: Annual Report for 1991 (Bibliographic reference). SPM563.

<5> Brennan, Naomi, 2020, Long Curtain and Southsea Castle Portsea Island, Hampshire : Additional GI Works Archaeological Watching Brief (Unpublished document). SPM641.