Event/Activity EPM242 - King's Bastion

Portsmouth Museum Service carried out an archaeological evaluation of the turf-covered remains of King's bastion in March 1992 ahead of a planned upgrade to the landscaping and general environment of the site. Four trenches were excavated at strategic points of the bastion to allow the recovery of information without disrupting any existing structural features. Trench 1 measured 20m x 1m x1m and ran between the outer-edge of the rampart slope on the south-west face of the bastion towards the centre. Mid-20th century turf and levelling material, consisting mainly of soil and gravel, was removed. The core of the bastion was revealed beneath the modern layers at approximately the original terre-plein level (surface of the rampart). This was made up of a clean yellow-orange gravel fill. No features e.g. revetment walls, were identified. Trench 2 was cut in two separate parts, 2a and 2b. Section 2a was situated at existing ground level to the northeast of the main bastion work. This section of trench measured 10m x 1m x 1m. Prior to excavation, sheds and an allotment belonging to the Parks Department had occupied this section of the site which had been levelled and was awaiting formal landscaping. A substantial limestone wall which had formed the north-east scarp revetment and the wall of the moat was revealed beneath the modern top-soil and levelling material. The wall was excavated by mechanical digger to 2.50m below ground level. It was not possible to excavate any deeper due to the loose nature of the backfill of the moat. Section 2b measured 12m x 1m x 1m. The same stratigraphy as trench 1 was recorded beneath 0.3-0.4m of modern turf and levelling. No structural remains of the bastion were revealed. Trench 3 measured 10m x 1m and was cut at right-angles to the west flank of the bastion. The same stratigraphy as trenches 1 and 2b was recorded, but in this case a substantial section of red-brick wall measuring 0.35m in thickness and 0.70 high was revealed 0.2m below the modern turf line. The wall had been constructed directly onto the underlying gravel. It was thought that a 'visible vegetation mark' may have indicated the survival of a 20m length of the same wall beneath the top soil and turf. Trench 4 measured 12m x 1m x1m and was cut at right-angles to the south-east face of the bastion. The general stratigraphy was the same as recorded in trenches 1-3. A 20th century cable trench was encountered 3m from the rampart edge and some brick rubble near to the line of the rear revetment wall. The report notes that investigations at King's Bastion had shown that, with the exception of a traversing-gun position at the apex of the bastion, all of the superstructure was demolished and the top of the earthwork levelled at approximately terre-plein level. All structures beyond the northeast flank had been levelled and the moat infilled.