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British hardened field defences of World War II

British hardened field defences of World War II were small fortified structures constructed as a part of British anti-invasion preparations. They were popularly known as pillboxes by reference to their shape.

Design and development

In May 1940, the directorate of Fortifications and Works (FW3) was set up at the War Office under the direction of Major-General G. B. O. Taylor. Its purpose was to provide a number of basic pillbox designs which could be constructed by soldiers and local labour at appropriate defensive locations. In the following June and July FW3 issued 6 basic designs for rifle and light machine gun, designated Type 22 to Type 27. In addition, there were designs for gun emplacements suitable for either the Ordnance QF 2 pounder or the Hotchkiss 6pdr gun (designated Type 28) and a design for a hardened medium machine gun emplacement.

There were also designs for pillbox-like structures for various purposes including light anti-aircraft positions, observation posts and searchlight positions to illuminate the shoreline. In addition, the Air Ministry provided designs of fortifications intended to protect airfields from troops landing or parachuting. These would not be expected to face heavy weapons so that the degree of protection was less and there was more emphasis on all-round visibility and sweeping fields of fire. Many of these were later reinforced.

Embrasures were available precast and factory produced to standard designs, but as these were in short supply some embrasures were improvised from brick or concrete paving. Embrasures were frequently fitted with a steel or concrete-asbestos shutter. From March 1941, some pillbox embrasures were fitted with a Turnbull mount, this was a metal frame that supported a medium machine gun.

The degree of protection offered by a pillbox varied considerably: the thickness of the walls and roof generally varied from just 12 in to 3 ft 6 in (0.3 to 3.2 m) or more although the commercially produced designs were often much thinner. In March 1940, General Brooke carried out penetration trials and recorded that a anti-tank gun could easily penetrate up to of reinforced concrete. Despite such results the thick-walled pillboxes were designated as shell proof whereas the thinner-walled pillboxes were designated as bullet proof.

Internally, pillboxes are generally cramped and spartan. Some internal concrete shelves and tables were provided to support weapons and some were whitewashed inside. Only the Type 28s provided a little space — sufficient for a few home comforts.

Adaptations

The basic designs were adapted to local circumstances and available building materials such that, outwardly, two pillboxes of the same basic design could look quite different. The height of a pillbox could vary significantly according to local needs: some were half buried so that the embrasures might be as low as ground level, others were raised up to give a better view; those built into hillsides might lack embrasures on some walls; the entrance could be moved and its size varied as might be convenient and there may be additional walls to protect the entrance, a freestanding blast wall or a steel door.

Appearance also varied due to the building materials used, although all the FW3 designs are formed from reinforced concrete. Where brick was used as a shuttering, the bricks essentially formed a mould into which concrete was poured, the bricks being left in place. Otherwise, the pillbox was formed using shuttering of wood (usually planks, but sometimes plywood) and/or corrugated iron. Wood shuttering was removed, whereas corrugated iron was sometimes left in place. Construction often took advantage of whatever materials were available locally (for example, at the coast, beach sand and pebbles would be used) and this expedient use of local materials had the added advantage of aiding camouflage. The reinforced concrete used in construction was generally conventional making use of thin steel rebars with floor, walls and roof all mutually bonded. However, several instances are known where scrap metal had been used such as parts of an old bed or park railings.

Local commanders introduced modifications to the standard FW3 designs or introduced designs of their own which may be produced in some numbers or completely ad hoc designs suited to local conditions. Other designs were produced as commercial ventures. Finally, there were a small number of pillboxes that had been constructed in the first world war.

FW3 pillbox types

The approximate numbers of extant pillboxes of each type are given based on data from the Defence of Britain database.

Type 22

The type 22 pillbox is a regular hexagon in plan with an embrasure in five of the sides and an entrance in the other. The embrasures are suitable for rifles or light machine guns. Some have a low entrance that allows an extra embrasure above. Each wall is about long and it was generally built to the bullet proof standard of thick, although 'tank-gun proof' versions with walls around thick were also built (e.g. the granite and concrete examples on the Cowie Line in Kincardineshire). Internally there is a Y- or T- shaped anti-ricochet wall (the top of the Y/T nearest the entrance), the internal wall also helps support the roof.

The type 22 is the second most common pillbox type with 1209 recorded as being extant. It is easily confused with the common type 24 which is an irregular hexagon and the less common octagonal.

Type 23

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. The embrasures are suitable for rifles or light machine guns. The open section was for a light anti-aircraft defence: a Bren or Lewis gun on a mounting. Usually, there is no ground level entrance, to get in one had to climb over the wall into the open section and then pass though a door to the covered section. The walls were wide by long and usually built to a bullet proof standard of thick.

The type 23 is uncommon, 156 are recorded as being extant.

Type 24

The type 24 pillbox is an irregular hexagon in plan. The rear wall is the longest at about , this has the entrance with an embrasure on either side. The other walls vary from each having a single embrasure. The embrasures are suitable for rifles or light machine guns. Internally there is a Y shaped anti-ricochet wall (the top of the Y nearest the entrance), the internal wall also helps support the roof. The type 24 was always built to at least bullet-proof standard of thick, but often was thicker.

A thick walled variant was introduced to a shellproof standard; it was larger externally and had walls thick. (This thick-walled variant is, confusingly, sometimes called a Type 29 by pillbox researchers, but this is not an official designation and should be avoided.)

The type 24 is the most common type with more than 1787 recorded as being extant.

Type 25

The type 25 pillbox is the only FW3 design that is circular with a diameter of . The walls were just thick with no internal walls. There were three embrasures suitable for rifles or light machine guns and a small entrance like a low window. This design was made from reinforced concrete shuttered by corrugated iron; this gave the design the popular name Armco after the manufacturer of corrugated iron of that name.

The type 25 is rare, about 46 are recorded as extant.

Type 26

The type 26 is a simple square in plan, each wall being long. There is a door in one side and embrasures in each of the remaining three walls with, possibly, an additional embrasure next to the door. There are no internal walls. Occasionally, there are two embrasures in one of the walls. The embrasures are suitable for rifles or light machine guns. Walls are normally constructed to bullet proof standard at about thick.

The type 26 also had an important prefabricated variant, the shuttering — both inside and out — was provided by precast concrete slabs slotted into reinforced concrete posts. The shuttering was filled with concrete in situ. This pillbox was also known as the 'Stent' after the company that produced the prefabricated components, Stent Precast Concrete Limited. On those examples where damage allows inspection of the construction, it seems that the concrete fill was not reinforced.

The type 26 is uncommon, 199 are recorded as extant.

Type 27

The type 27 is the most varied of the FW3 designs, it may be an octagonal or hexagonal in plan with walls between 9 ft 9 in and 11 ft 6 in (3.0–3.5 m). The outer walls being thick and have embrasures suitable for rifles or light machine guns on each facet. Its defining characteristic is a central well open to the sky that could be used as a light anti-aircraft position.

Type 27 is uncommon, 127 are recorded as extant.

Type 28

The type 28 is the largest of the FW3 designs and the only one with a specific anti-tank capability. It is almost square in plan with the forward facing corners chamfered. The walls are each about 20 feet by 19 feet (6.1 by 5.8 m) long constructed to shell-proof specification at about thick. There is a very large forward embrasure. It was designed to take a 2 pounder anti-tank gun or a Hotchkiss 6pdr gun. The gun shield of the artillery piece would largely fill the aperture. There are usually embrasures suitable for rifles or light machine guns in each of the two side walls.

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.

The type 28A is an important and common variant. 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. This resolved the problem of the type 28 being vulnerable to a head-on infantry attack.

A further, rare, variant is the type 28A twin, which has two main gun embrasures on adjacent walls giving two possible firing positions for the one main gun and together with two adjacent infantry sections.

The traverse of the gun was limited to about 60°. Generally, these pillboxes were positioned to fire along fixed lines, such as enfilading fire across an anti-tank ditch or at a bridge and in such positions the limited traverse of the gun creates no real disadvantage; whereas, the small size of the embrasure provides greater protection for the gun and its crew.

The type 28 and its variants are fairly common, there are some 350 or so recorded as extant.

Vickers MMG emplacement

The Vickers machine gun pillbox is essentially square in plan with the forward facing corners chamfered. The walls are long and there is generally a freestanding blast wall covering the entrance on either the left or right side. The walls were constructed to shellproof standard of . There are no internal walls. There is a large embrasure and inside is a concrete, trapezoidal table on which to mount the weapon's tripod. The other walls would each have an embrasure suitable for a rifle or light machine gun.

These emplacements are only to be found on the Taunton Stop Line and on GHQ Line around Aldershot. They are frequently sited in pairs and were often dug-in with overhead earth cover.

Vickers MMG emplacements are uncommon, just over 75 are recorded as extant.

Other hardened defences

Field gun emplacements

There were a wide variety of field gun emplacements, most resembled larger version of the Type 28 pillbox.

Lozenge pillbox

The lozenge pillbox is found only in the North East of England. 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 rear wall has two embrasures and an entrance. The four short walls each have a single embrasure. Internally, an anti-ricochet wall runs longitudinally. It was designed for infantry armed with rifles and/or light machine guns.

Eared pillbox

The eared pillbox is, like the lozenge pillbox, found only in the North East of England and has an irregular hexagon plan. There are two large embrasures intended for medium machine guns. There is a bulge at the base of the wall below the embrasures that is thought to have accommodated the cooling system for the machine gun. Internally, there is a short anti-ricochet wall.

The two embrasures are at 90° to each other giving an arc of fire of about 180° with no way to direct fire behind the pillbox. This design is frequently found on or near beaches — ideal for providing enfilading fire. There are two entrances with openings in the same direction as the embrasures.

Lincolnshire three-bay

Found only in Lincolnshire, this type has become known as a Lincolnshire three-bay pillbox. It is essentially a modification of the FW3 type 23 having an open light anti-aircraft position in the centre and fully enclosed bays at either end.

Dover Quad

The Dover Quad pillbox is a square pillbox with wide embrasures and an overhanging roof slab. This design is only found in the Dover area of England and are very often found at high commanding positions. Some commentators opine that the Dover Quad is a poor design: the overhanging slab, while offering some protection from strafing, is liable to ricochet bullets from below into the embrasure which is, in any case, wide giving inadequate protection. Given the vulnerability of the port of Dover, it is possible that these were among the first WWII pillboxes constructed and they may have pre-dated the FW3 designs, but there is no evidence for this.

Section post

Section posts are essentially hardened trench works. Constructed to bullet proof standard, they are long and have a large number of embrasures. Shelves of wood or concrete are fitted below the embrasures in the principle direction.

Somerset Defence Post

The defence post is only found in Somerset, it is about square with walls about thick and have wide slits extending the full width of three faces. There is a porch covering the entrance. Some have an open section on top reached by rungs and a ladder.

Norcon pillbox

The Norcon was a small circular pillbox named after the company that manufactured it as a private commercial venture. It was made from a concrete pipe diameter and high, the walls were of non-reinforced concrete with several cut loopholes. Described as being possibly the most dangerous, cheap and nasty of all the pillbox designs. Being quick to manufacture was its biggest asset, it was possible to turn out about 20 a day the concrete being cured in about 24 hours but few were actually built. The standard model lacked a roof, others had a roof made of timber and corrugated iron, and earth; extra protection was provided by the use of sandbags.

Ruck machine gun post/pillbox

Designed by James Ruck, constructed from Stanton air raid shelter sections and was covered in additional concrete slabs. The segments were made at the Stanton Ironworks Ilkeston Derbyshire in the Concrete Plant which converted from production of concrete lighting columns during the war. "The segments were 20 inches (50 cm) wide and 2 inches (5 cm) thick, a pair of them formed an arch 7 feet [2.1 m] high and transverse struts were provided to ensure rigidity. These fitted into longitudinal bearers, which were grooved to receive the foot of each segment. Each pair of segments were bolted together at the apex of the arch and each segment was also bolted to it neighbour, the joints being sealed with bituminous compound. The convenient handling of these segments enabled them to be transported with ease. Partly buried in the ground and covered with turf and sandbags, with a suitably screened entrance, this bolted arch construction afforded safe protection against blast and splinters. The Ruck machine gun post was relatively widely used in Lincolnshire and along the east cost of England, but is now extremely rare with just a couple of extant examples.

Pickett-Hamilton Fort

The need to defend airfields presented special problems. Airfields were large open areas where any above-ground structure would present a hazard to aircraft. 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. The fort was manned by a crew of two with light machine guns. Access was provided by means of a hatch in the roof. The forts were prone to flooding and they were not sufficiently strong to bear the weight of the heavy aircraft developed during the war.

Alan Williams Turret

Pillbox formed by a metal turret, which could be rotated through a full 360 degrees, set above a steel and brick-lined pit. It was designed for all types of light 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. It could also be armed with the Boys anti-tank rifle. The army did not favour the design, most were installed at airfields.

Nearly 200 Allan Williams Turrets were made and installed, salvaging of the metal after the war means that today very few remain.

Tett Turret

The Tett Turret was produced commercially by the Burbridge building company of Surrey. It was a two-man pillbox with a revolving concrete turret mounted on a ball race set above a cylindrical concrete pit formed by a standard section of concrete pipe in diameter. The top was open and vulnerable to a well thrown grenade, it provided the only means of egress which would have been very dangerous under fire.

Spigot mortar emplacement

A spigot mortar emplacement was unroofed, sometimes constructed of brick or concrete, but may be a simple revetted earthwork. Its defining characteristic is a central concrete pedestal with a stainless steel peg (rust free even after more than 60 years). The pedestal was for a type of spigot mortar called the Blacker Bombard — effective against both tanks and personnel — at ranges of about and respectively.

Embrasured walls and buildings

Existing walls and building provided a ready-made alternative to a pillbox. Whatever may be lacking in protection was made up for by speed and convenience.

Camouflage

Detailed instructions were given for the careful concealment of pillboxes and other field defences and all pillboxes would have been camouflaged. 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. Camouflage paint schemes and camouflage netting would be used to help break up the outline. Use was made of local materials: concrete made with beach sand, a covering of beach pebbles, or stone from a nearby cliff was not only a time saving measure but aided camouflage by helping the defences to merge into the background.

Artists such as Roland Penrose (author of the Home Guard Manual of Camouflage), Stanley William Hayter, Julian Trevelyan and many others were employed to conceal defences. In built-up areas pillboxes were disguised to look like a part of an adjacent building, carefully matched and provided with a roof to look as if they had always been there. In extreme cases, they were built inside existing buildings.

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. It was not uncommon for pillboxes to be fitted with a dummy pitched roof to aid the deception. Some of these disguises bordered on the fanciful.

In some cases, the reinforced concrete roof was sculpted to make the distinctive form of a pillbox less obvious from the air.

Destruction, neglect, rediscovery and reuse

The great majority of Britain's static defences have been destroyed, a process that started even before the end of the war. Ditches and trenches have been filled; loopholes repaired; wood and metal re-cycled.

After the war, farmers, across whose land structures had been built were, in addition to receiving compensation, paid to fill in ditches and trenches and to demolish pillboxes. Today, hardly anything remains of the anti-tank ditches, but at the time they must have been the most conspicuous of all the fortifications; a few remain, much humbled, as field drains or field boundaries whereas others can be seen only as crop marks. In the case of pillboxes, the sum of £5 is sometimes mentioned to pay for demolition, but the challenge of demolishing such structures is considerable and it seems that most farmers pocketed the cash, treating it as compensation.

Today, it is very rare to find any part of Britain's defences other than that composed of concrete. Immediately after the war, there were more pressing matters to attend to than conserving the detritus of a battle that never happened. For decades, with the sole exception of Pevensey Castle — where the new fortifications were seen as a part of the building's history — there was never even a suggestion that anything should be deliberately conserved.

As the years passed, erosion and modern construction destroyed many structures: at the coast fortifications have tumbled into the sea or sunk into the sands on which they were built; yet other features have succumbed to road improvements or have been demolished to make way for other modern developments. For many of those that remain, neglect and the attentions of nature have achieved a degree of camouflage greater than that of during the Second War.

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. Even the Home Guard came to be seen as something of a joke as exemplified by the BBC sitcom Dad's Army. Whereas, in fact, what can be seen today are just the most visible and robust remains of what was a massive programme of fortification that was likely to have proven highly effective.

Extant war-time 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 leading to publication of Pillboxes: A Study of UK Defences in 1985. Interest was stimulated, both public and professional; local surveys were carried out. Surveys culminated in the Defence of Britain Project which took place from 1995 to 2002 attempting to record all known military defence sites. From this and other surveys, it is estimated that some 28,000 pillboxes and other hardened field fortifications were constructed in the United Kingdom of which about 6,500 still survive. The project also resulted in the discovery of many relevant records.

For many pillboxes, a new use has been found. 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.

Some pillboxes have been converted to make roosts for bats. 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. With a few minor modifications, suitable pillboxes can be converted to artificial caves for bats.

Notes

References

General References

* * * * *

Denison, Simon (2002). "Fortress Britain". British Archeology (65): Retrieved on 2007-03-10.
Newark, Tim (2007). "Now you see it... Now You Don't.". History Today

WW2 People's War is an online archive of wartime memories contributed by members of the public and gathered by the BBC. The archive can be found at http://www.bbc.co.uk/ww2peopleswar/.
The Stanton Ironworks Co. Stanton at War 1939-45. The story of the part played by Stanton Ironworks with reference to making of the concrete sections for a Ruck Machine gun post/Pillbox.

Official documents

Camouflage: Military Training Pamphlet No. 46. Part 2: Field Defences (July 1941) The War Office.

External links

General

The German Threat to Britain in World War Two. By Dan Cruickshank. BBC website.
The Real Dad's Army - TV Documentary.
Pillboxes for bats
Pillboxes on BBC Inside Out website.
English Heritage: Understanding & Recording Military Sites.
Churchill's mysterious map.
Building Pillboxes: A Personal Story by E. S. Hardie. Pillbox Study Group
Pillboxesuk.co.uk.

National

Defence of Britain database.
Pillbox study group.
Pillbox Study Group A 300 member group dedicated to the study and preservation of 20th Century Anti-Invasion Defences. The groups 200 page website details many specific defences in great detail and specific sites are listed by the members throughout Britain and the world. Membership is open to all interested in these defences. Please visit the site for more details.
Pillboxes UK Details of many specify sites throughout Britain.

Regional