Monument MPM24 - Mill Redoubt

Mill Redoubt formed part of the remodelled line of Portsmouth defences designed by Sir Bernard De Gomme and constructed 1668-1685. The redoubt protected a large tidal mill known as the King's Mill/Beeston's Mill (see MPM1013). It was also one of the gateways to the town of Portsmouth (now Old Portsmouth), and the road between the town and the dockyard passed through it. The remains of the redoubt, including sections of limestone wall, were recorded during excavations in the 1990s and early 2000s.

The site of the former King's Mill (tidal) and the Mill Redoubt (gun platform) of late-17th century date. Demolished and levelled in the late 19th century. Trial excavation prior top development.

[1]

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Excavations on the site in 1995 revealed substantial limestone-built foundations 60cm below the ground surface, and part of the south wall of the redoubt (1.5m in section). A red brick footing (3.5m in section against inner face), may have been part of an expense magazine located in the sheltered area to the rear of the redoubt. The back fill of the Mill Pond consisted of soil, gravel, cobbles and red bricks. Brick rubble infill observed in the north of the site was thought to relate to post Second World War levelling. Visible disruption of levels was attributed to bomb damage - records show a bomb crater a few metres to the northwest. [2]

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Remains of the west, northeast, and south walls to the redoubt were observed in three trenches during an archaeological evaluation in 1997. The west wall was encountered 75cms below ground level, and measured 2.24m wide. Its outer (west) side had been faced with limestone blocks with a batter or slope, which survived 82cms below ground level. The inner (east) face had been more crudely constructed. The walls core (between the inner and outer faces) was made up of small stones set in a lime-based mortar.

The east wall was revealed 56cms below ground level. The outer (east) face and core of the wall were of the same construction as the west wall (see above). The inner face of the wall was not exposed. In the south of the trench the top of the wall had been destroyed by an iron service pipe. A 34cm thick brick wall was revealed towards the east end of the trench.

The south wall was encountered 88cms below ground level, and comprised a single line of limestone blocks 35cms wide. The blocks appeared to have a vertical face on the external (south) side. The south side of the redoubt is shown as a relatively narrow wall on maps, which corresponds with the archaeological evidence. The south was the only wall of the redoubt not to have a parapet and gun emplacements.

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An excavation by Gifford and Partners in 2000 exposed the remains of several features relating to the redoubt. Two trenches were excavated, one in the area of the southeast corner of the redoubt, and a second on its northern tip (apex). The excavation identified a total of 6 phases of occupation/use of the site, the earliest of which were 17th century deposits relating to the Mill Dam Causeway on which the redoubt was constructed (in use 15th-17th century). The phases of use identified for the redoubt itself dated from its construction in 1680-1710 through to its demolition in 1870-1880.

A large number of finds were recovered from the site. These included 65 sherds of post-medieval pottery and a large quantity of clay pipe fragments. A single sherd of medieval Saintonge ware from a polychrome vessel was also recovered, although this may have been residual. Animal bone largely consisted of sheep, goat, cattle and pig, although the remains of other animals including cat, dog, hare and badger were also recovered. Metal objects included nails, coins, dressmaking pins, a lead musket ball and probable lead gaming counters. Large quantities of brick and peg tile were recovered, together with a small quantity of ridge tile and daub fragments. A number of large stone building blocks were encountered on the site but not retained, with the exception of a large square block shaped to form a Classic cornice for a Roman or Greek style column. Fragments of glass belonging to the windows of the 18th century guardhouse were recovered, together with fragments of bottle and vessel glass.


Summary of features:


Southeast Section

Walls, southeast corner of redoubt
Substantial stone walls belonging to the southeast corner of the redoubt survived to a height of 2.2m O.D, the facing stones having been robbed out. The tops of the walls had been covered by the back fill of the Mill Pond.

Mill Gate Passageway
Two parallel walls and a rammed mortar surface represented a section of the Mill Gate passageway, which originally ran from Old Portsmouth to the Dockyard. The remains of a single cart run were visible on its eastern side. The walls survived to a height of 1m above the mortar surface.

Buffer Zone?
Large gravel filled area enclosed by stone walls. Situated to the southeast of the Mill Gate passageway and immediately to the east of the guardroom. Possibly used as a buffer to limit the impact of an attack.

Guardroom
The remains of the original guardroom, built c1700, were revealed. The walls were constructed using unfrogged red bricks, and the floor was half cobbled and half floor-boarded, the wood having rotted away. Numerous personal items were recovered from within the room. Earlier levels of occupation and ground make-up cut by the construction trenches for the guardroom were observed to a depth of 1m O.D below the guardroom floor. These levels related to the later phases (17th century) of the Mill Pond Causeway and the construction of Mill Redoubt. The guardroom was demolished during the early 1800s, when a new guardhouse was constructed on the western side of the parade ground.

Room 2
A deep room enclosed by stone walls, with a wooden floor and brick hearth, exact function unknown. At least two phases of occupation were identified, the first dating to 1710-1745, the second 1745-1870. During the second phase the wooden floor was relayed, the room shortened, and the hearth decreased in size. A wooden staircase would probably have been used to access the room, although no evidence survived. A small section of stonewall footing observed below the first phase of flooring and wall foundations may have related to an earlier structure.

Steps
A triangular stone footing situated between the guardroom and second room, represented the 19th century steps which lead to the ramparts.


Northern Section

Apex (northern tip)
Substantial remains of the apex of the redoubt were revealed approximately 0.4m below the modern ground surface.

Walls, western side
The west-facing wall had been dressed with limestone blocks and survived in places to a height of 2.8m O.D.

Walls, eastern side
The stone from the upper part of the east-facing wall had been robbed and it was badly damaged. The internal structure of the redoubt had been constructed using rough-hewn limestone boulders bonded with lime mortar.

Dam Wall, Mill Pond
The remains of the dam wall were bonded into the internal structure and facing of the redoubt, suggesting that it dated to at least the mid-17th century when the redoubt was constructed. The wall had the same construction as the redoubt, with a limestone rubble core faced on the seaward and Mill Pond sides. Evidence of metal ties used to strengthen the wall was visible in the seaward facing.

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A section of the west wall (at the northern 'point' of the redoubt) was also revealed during a watching brief in 2002. [5]

<1> Portsmouth City Council, n/a, Portsmouth City SMR Cards, SZ69NW23 (Index). SPM1.

<2> Fox, Russ, 1995, H M Gunwharf Old Portsmouth Archaeological Excavation/Assessment 1995 (Unpublished document). SPM65.

<3> The Conservation Practice, 1997, Gunwharf Quays, Portsmouth, An Archaeological Evaluation. Part Two: Site Investigation (Unpublished document). SPM326.

<4> Barge, M, 2000, Mill Redoubt Excavation, Gunwharf Quays, Portsmouth: Assessment Report (Unpublished document). SPM325.

<5> Gifford and Partners Ltd, 2003, Ariadne and Piazza, Gunwharf Quays, Portsmouth: Results of the Archaeological Watching Brief (Unpublished document). SPM315.