British hardened field defences of World War II

[2] Having very few tanks or lorries to form such a reserve, Ironside formulated a plan to have a "coastal crust" of defended beaches, backed up by a network of "stop lines" which would limit any incursion, with localised defences for "vulnerable points" such as airfields.

Its purpose was to provide a number of basic but effective pillbox designs that could be constructed by soldiers and local labour at appropriate defensive locations.

The reinforced concrete used in construction was generally conventional making use of thin steel rebars with floor, walls and roof all mutually bonded.

[citation needed] The type 23 pillbox is rectangular in plan – essentially two squares, one of which is roofed and the other open – with embrasures in each of the available sides of the covered section.

[41][42][43] Superficially, the type 28 resembles the smaller Vickers MMG emplacement, but the aperture is much larger and there is a very large rear entrance designed for ease of wheeling the gun in and out.

It is wider than the type 28 to allow for a side area for an infantry chamber, giving a forward-facing embrasure suitable for a rifle or light machine gun.

Lozenge pillboxes are an irregular hexagon in plan with the front and rear walls significantly longer than the others; this allows space for four forward-facing embrasures.

The mirrored front and back embrasures were intended to allow fire in both directions so the pillbox could not be flanked or bypassed by troops that managed to penetrate inland.

Given the strategic importance of the port of Dover, it is possible that these were among the first World War II pillboxes constructed and they may have pre-dated the FW3 designs, but there is no evidence for this.

It varies from that type by having Bren embrasures in the three front faces and the entrance at the rear rather than one side, covered by a very thick blast wall.

[69] The Royal Ordnance Factories (ROFs) and depots were critical to the war effort and considered vulnerable to enemy ground attack so were often protected by pillboxes.

These were small flat-roofed square pillboxes, usually with distinctive long narrow embrasures in at least three of their sides; the door was usually low and protected by a blast wall.

[78][79][80] The Ruck machine gun post was relatively widely used in Lincolnshire and along the east coast of England,[81] but is now extremely rare with just a handful of extant examples.

One solution was the Pickett-Hamilton Fort; this was designed to be lowered to ground level while aircraft were operating, but to be raised when necessary by means of a hydraulic mechanism.

It was designed for a machine gun to be fired either through the front loophole which was further protected by shutters, or through the circular opening in the roof in a light anti-aircraft role.

[92][93] Known survivors include: two at North Weald Redoubt, Essex; one on display at the Imperial War Museum, Duxford (recovered from an Essex village); one at Worbarrow Bay, near Tyneham, Dorset; one at Seacombe, Dorset; one, above ground but missing its sliding doors, in the grounds of Bayfield Hall, Holt, Norfolk; one on the seawall at Cley next the Sea, Norfolk; two at Cockley Cley, Norfolk; two at Bembridge Fort, Isle of Wight; one at Plymstock quarry, converted into a blast shelter for quarrying (now relocated to Knightstone Tea Rooms at the former World War II RAF Harrowbeer Airfield, near Yelverton[94]); one at Exmouth seafront, Devon (re-located from docks); one at Builth Wells war memorial, Wales; two on display at Sywell Aviation Museum, Northampton; one at the former RAF Llandwrog near Caernarfon, and one at RAF Dishforth.

[98] Existing thick walls and heavy buildings provided a ready-made alternative to a pillbox and many were converted to defensive positions by the simple expedient of adding embrasures to them.

Many were dug into the ground or inserted into a hedgerow or hillside to provide the lowest possible profile; others had soil piled up on the roof and sides.

[102] Artists Roland Penrose (author of the Home Guard Manual of Camouflage),[103] Stanley William Hayter, Julian Trevelyan and many others were employed to conceal defences.

Some pillboxes were carefully constructed to resemble a quite different, innocent, structure: a haystack, a disused cottage, seaside kiosk, bus-stop shelter or railway signal box.

[citation needed] Along part of the Taunton stopline in Somerset, due to the shortage of material available, six pillboxes were coated with a mixture of cow manure and mud topped with straw as a form of natural concealment.

During the summer months, a scarecrow "family" and a horse made of straw were dressed and suitably arranged around the caravan to visually disguise the fact that it was actually a manned pillbox.

[citation needed] In addition to receiving compensation, farmers whose land was used to build the structures were paid after the war to fill in ditches and trenches and to demolish pillboxes.

At the coast, fortifications have tumbled into the sea or sunk into the sands on which they were built;[110] yet other features have succumbed to road improvements or have been demolished to make way for other modern developments.

[111] Years after the war, memories faded and in the public mind it became popular to assume that the few pillboxes and other concrete objects that could easily be seen were all that was done to defend Britain; that their purpose was just to bolster morale and that there would have been no realistic hope of resisting a German assault.

[113] Extant wartime records were thought to be fairly poor, and nobody could be sure how many pillboxes and related hardened field defences had survived—or indeed, how many had been constructed in the first place.

In the late 1970s, journalist Henry Wills began research on the topic, eventually publishing Pillboxes: A Study of UK Defences in 1985.

The type 28s, being internally spacious and having a large rear entrance, are probably the most amenable to reuse and on farms, and in gardens they serve as cattle sheds and storage lockers.

Other, more imaginative, pillbox applications recorded include use as a pub cellar, a conversion to a ladies' toilet, and an open-air theatre box office.

Pillboxes that are well dug-in and thick-walled are naturally damp and provide a stable thermal environment that is required by bats that would otherwise hibernate in caves.