Fort Purbrook, That Part in Portsmouth Church Parish

Fort Purbrook, that part in Portsmouth Church Parish

Fort, built around 1860, designed by Captain William Crossman of the Royal Engineers. It is one of a series of forts built along the chalk ridge of Portsdown Hill, including Wallington (now demolished), Nelson, Southwick, Widley and Purbrook. These forts were constructed in the 1860s for the defence of Portsmouth against landward attacks and became known as Palmerston's Follies.

The fort features brick walls in English bond. The outer face of the defensive walls is of flint with horizontal and vertical bands of brickwork and a blind arcade at the upper level. The structure follows a polygonal plan with four vertical faces to a deep dry ditch. Behind the parapet is a firing step, and two-storey caponiers are positioned at the north-east and north-west corners to provide raking fire along the ditches. Within this outer framework is an embankment with open gun emplacements at the top.

Beneath the central parade ground lie deep underground tunnels accessed from the centre of the north face of the barrack block. The entrance is within the musketry gallery, which has firing slots and is roofed in pitched brick with a circular brick ventilation stack and cone. Passages lead to ammunition stores, expense magazines, staircases and caponiers. The tunnel to the north-east caponier descends through exposed chalk and flint, whilst the north-west tunnel is brick lined. Behind the caponier position are sunken embrasures for mortars.

On the exterior, the main entrances, a V-shaped barrack block with internal courtyard, stores and stable blocks are positioned on the south side facing Portsdown Hill road, approached by inclined roads. Each of the two main entrances is set within a thick brick curtain wall featuring a Norman-style entrance with round arch and attached columns, moulded dripstone with dropped bosses. To the right of the right-hand entrance are nine low-level firing slots, and further right at a higher level are twelve paired and one single firing slots, each with recessed raked brick jambs and flat concrete lintel. To the left of the entrance are two bays, each with a ground and first-floor four-paned casement set under a round brick arch, with a firing slot on each side of the casement set under a flat concrete lintel. Each front face of the V-shaped barrack block has seven similar bays with similar windows and firing slots to ground and first floors. A large castellated brick parapet and earth-filled roof set on vaulted brickwork complete the design.

The fort contains many interesting details of fortification design. It is similar to Fort Widley except for the V-shaped barrack block and has two caponiers instead of three. The fort is mainly within the boundary of Havant District Council and is listed there also; the southernmost part is within the Portsmouth City Council boundary. It is designated as a Scheduled Ancient Monument.