The pillbox is synonymous with the Second World War. Thousands were constructed across the United Kingdom (and Ireland1A programme of defence building was undertaken by the Irish along the River Boyne and around a number of south coast ports) to defend high-value areas or as part of a National defensive line. Many of them still remain and conjure up the romantic notion of local boys and men bearing arms to defend their country. Their modern interpretation is often the subject of much controversy with the context of their construction having been lost in the preceding 80 years. The area which is now Randalstown Forest has three pillboxes remaining, each with unique features, and the relationship between each one and where they sit in the landscape offering clues to help interpret them. In this article, I will attempt to place the pillboxes in the context of defending against invasion, and also look at each structure in turn to find clues about their construction and use.
Background
The declaration of war in 19392Preparations for war had been undertaken during the preceding years including the development of new aircraft, research into early warning systems and civil contingent planning. saw an overnight change to the lives of citizens across Great Britain and Northern Ireland, but in these early days of the was there was little feeling that the population was in any great danger. It was another foreign war where the might of Great Britain and Her allies would prevail; even if the events of 1914-1918 were still very much present in everyone’s mind. I am sure there was dread at the thought of another generation of young men being sent to their fate, but in the early days at least the future didn’t look as bleak. However, the so-called Phoney War was soon to come to a bitter end. When the 390,000 strong British Expeditionary Force (BEF) was dispatched to France and Belgium in October 1939 they dug-in and waited for the war to begin. But for the next 7 months, there was little divisive action from either side. By May 1940 the heat was on and this vast force, along with French and Belgian counterparts, was engaged in the Battle for France. Within a month the BEF had been evacuated and the British Army had lost sufficient war-fighting equipment that they would almost certainly struggle to repel the German Army had they continued their push westward.
The first serious plans for the defence of Britain drawn up by General (later Field Marshall) Ironside, Commander-in-Chief Home Forces, relied on lines of continuous static defences, similar to those used (without great success I hasten to add) in France during the early days of the War. In 1940 a vast programme of construction was initiated comprising a thick ‘coastal crust’ of defences and a series of linear defences known as the General Headquarters (GHQ) line along the east coast of England. This was to be supplemented by smaller ‘stop lines’ across the country to hinder any advance if the Germans penetrated the GHQ line.
Northern Ireland received little attention in the early days, having been considered to be out of the reach of the invaders. Ironside, however, was concerned that neutral Ireland (and Northern Ireland by association) could be used to mount an invasion of England from the west. In the summer of 1940 reconnaissance of Northern Irish beaches was ordered.3British planning and preparations to resist invasion on land, September 1939 – September 1940. Newbold, David John, 1988
During the summer and autumn of 1940, counter-measures were taken to prepare a hot reception for the potential raider or invader. By means of concrete pillars, barbed wire and concealed firing points (…)
Chapter 5, the Threat of Invasion, Northern Ireland in the Second World War, John W. Blake, 1956 (reprinted 2000)
Ironside was succeeded late in 1940 by a Ulsterman; General Alan Brooke, who recognised the weakness of purely linear defensive lines and immediately halted Ironside’s plans. While the new plan incorporated much of the existing infrastructure, Brooke implemented a series of well-defended nodal points at natural junctions and focal points. Towns and villages became centres of resistance, while rivers and valleys became defensive features to channel any invaders towards the well-defended localities. This new plan combined the relatively flexible and inexpensive field defences with the more permanent hardened defences. These defences were independent of those constructed for the defence of specific areas such as factories, airfields or industrial areas.
A demonstration by the Royal Berkshire Regiment from October 1941 shows what a roadblock may have looked like. It is likely that the approach roads to Randalstown would have been furnished with similar obstacles and defences. The large concrete blocks have been cast with corrugated iron as a mould. The square slots along the edge are for steel beams such as railway sleepers, so it is unusual that a rope has been used in their place; unlikely to be a deterrent to anything larger than a motorcycle as in this exercise. And as with all obstacles, they would have been overlooked by protected rifle and machine-gun positions.
Image right from the Imperial War Musem IWM H 14838.
Spotting a pillbox in the landscape today we often see red-brick clad bunkers sticking discretely above the landscape. This isn’t how they would have looked when concealed into the landscape. many techniques were used to hide the pillbox from view; both from the air and aerial reconnaissance and from passing patrols. One of the main principles employed in the camouflage of pillboxes was that of “merging with the background by elimination of shadows and the distortion of the silhouette.”4Military Training Pamphlet, No. 46, Camoflague, Part 2, Field Defences, 1941. Some examples of how a pillbox may have been merged are given in a 1941 pamphlet (left). Pillboxes were also disguised to great effect, especially in coastal towns or urban environments. There are some excellent images of camouflaged pillboxes on the Imperial War Museum archive.
Image left from Military Training Pamphlet, No. 46, Camoflague, Part 2, Field Defences, Figure, 12, dated 1941.
It’s also false to assume pillboxes were independent structures. Certainly, they formed a static stronghold in a defensive line, and they would likely have housed the more high-value weapons such as machine guns or anti-tank rifles. Other defences such as barbed wire entanglements, anti-tank blocks and ditches, and infantry trenches would have accompanied the pillbox in creating formidable defences. One type of defence that may well have been dug around these pillboxes in a 3-man weapon slit (right), the instructions for which were issued to troops in the Field Service Pocket Book.
Image right from Field Service Pocket Book Pamphlet, No. 7, Field Engineering, Figure 3, dated 1944.
By mid-June 19405Northern Ireland in the Second World War, John W. Blake, Chapter V: the Threat of Invasion, Section 2, footnotes there were up to 20,000 regular ground troops under the control of Headquarters Britsh Troops Northern Ireland (HQ BTNI). This was primarily 53rd (Welsh) Division responsible for Fermanagh, Armagh and South Down; 61st Infantry Division with responsibility for Antrim, Londonderry and Tyrone, including Belfast; and 148th Infantry Brigade Group. They were joined in early 1941 by 71st and 72nd Brigades and the entirety of 5th Division. Just as the threat of invasion was waning there were four divisions garrisoned in Northern Ireland as an anti-invasion force. The thought that the Germans would have been fought off by a hotch-potch Dad’s Army was incorrect.
Interpreting the Randalstown Pillboxes
A transport and industrial hub for over 200 years, Randalstown sees the congregation of roads from the north, east and west, as well as being located on the River Maine with its substantial railway viaduct. For any invading army to dominate this region, capturing Randalstown would be vital. The one set of natural obstacles preventing swift advance across the country we have an abundance of in Ireland; rivers. Many of which start or end in Lough Neagh and Randalstown is a mile from the shore.
As well as being prepared for defence as a Nodal Point, the bridges crossing the River Maine were had been prepared under a demolition scheme for destruction had the order been received. It is estimated that one Battalion of Infantry along with a Field Company of Royal Engineers could garrison a village for complete defence within 24 hours.6Royal Engineers Pocket Book, Chapter IV Defences, 1936. They would have required 800 long pickets, 1600 short pickets, 130 coils of barbed wire and three 3-ton trucks. Any enemy transit through Randalstown would be very difficult indeed.
With a huge programme of work undertaken in the spring and summer of 1940 at the direction of General Ironside, the three pillboxes outside Randalstown may have been constructed at this stage. It can only be assumed that they were surrounded by other field defences such as infantry trenches and barbed wire. I think it is unlikely that there was a continuous chain of pillboxes from Randalstown south to the shores of the lough along the river. Providing a formidable obstacle to any advancing troops attempting to move east across the country, these pillboxes with their light machine guns and mobile infantry would have had a great impact. They dominate this section of land, use the landscape to their advantage, and exploit the natural obstacle of the River Maine to their rear.
At the stage of the invasion where these pillboxes have entered the fight, it is likely that all bridges across the River Maine would have been intentionally destroyed. It is possible that these three pillboxes protected a crossing point to facilitate reinforcement or evacuation of troops to and from the frontline. Troop movement in and out of the area behind the pillboxes would have been covered from sight and direct fire. A small bridge does exist and can be seen to the bottom left of the image below. Information on the NI Historic Environment Map Viewer does not have this bridge listed as a prepared demolition site.
In the defence of a bridgehead over a river, the passage of which it is required to keep open with a view to a future advance, it will be necessary to locate troops in sufficient depth across the river to prevent enemy observed fire from being directed against the bridge.
The Infantry Division in Battle, Section 20, The Defensive Layout, 1950
The three pillboxes sit almost exactly at the connection of the 500-yard rings, demonstrating that they have been sited very carefully so as to provide mutually supportive fire to each other, and can effectively deny freedom of movement to exposed enemy infantry anywhere within their range.
To achieve the greatest effectiveness of this position the pillboxes would have housed LMGs. The allocation of Bren Guns for an infantry division was anywhere upwards of 740 guns7WWII Equipment but after the losses of Dunkirk it’s not possible to know how many were initially deployed in Northern Ireland. By June 1940 it appears that there a total of 3,447 Brens available to the British Army.8WWII Equipment Ammunition does not appear to have been in short supply due to the rapid increase in war production.
(The Light Machine Gun) is the principal weapon of the infantry section and can be fired and maintained in action by one man. It can fire single rounds or produce automatic fire at a very high rate, if required, up to a normal effective range of 600 yards. When fired from a tripod this effective range may be considerably increased.
Infantry Training, Volume I, Pamphlet No. 6, The Light Machine Gun, 1948
Typology
The pillboxes at Randalstown are all of the same type; a variation on the Type 24 design of pillbox issued in May 1940.9Pillboxes of Britain and Ireland, Mike Osborne, 2008 (2012 reprint) They are of a hexagonal design with a longer rear wall to accommodate a full-height door and two smaller loopholes. There could be considered three front faces to the pillbox, each having a full-size loophole to direct the greatest volume of fire to the front arcs. Two final loopholes are in the flanking faces of the pillbox facing the rear flanks.
The Type 24 was one of the most common designs of pillbox constructed on Stop Lines in England, the majority of which had a central Y or X-shaped anti-ricochet wall designed to prevent bullets entering one loophole passing through the full pillbox and richoeting around the inside. None of the three Randalstown pillboxes have this feature. Many also had a blast wall covering the rear entrance providing some protection to the occupants from exploding shells to the rear.
There were two specifications of pillbox; bulletproof and shellproof. Bulletproof pillboxes (of which the variants at Randalstown are) had a wall thickness of between 30-40 centimetres and a concrete roof slab thickness of around 30cm. Shellproof pillboxes were twice the thickness with walls up to 130cm and were designed, as the name suggests, to resist shelling from field artillery. You can find out more about the thickness of protective materials required in my article Field Fortifications: ow thick was thick enough?
Shanes Park Pillbox
The exterior of the pillbox is unremarkable and distinguishable as a Type 24 bulletproof constructed with red-brick shuttering and a slab concrete roof cast in-situ. 
Detail of a loophole; a prefabricated lintle has been used atop a loophole stepped from red brick. 
The interior of the pillbox is in relatively good condition, but all metal work has been removed. There is no anti-ricochet wall in the Randalstown pillboxes, but a central column constructed of red brick seems to be common to all three, likely providing structure to the roof slab during casting. The column remains in the southern pillbox. 
A full height rear door is present in all three pillboxes, with no external blast wall. The floor has been laid in red brick which is a rareity; perhaps saving scarce concrete that would otherwise have been used to cast the foundation and flooring slab. 
Detail of the remains of a red brick column that may have been utilised to support the roof slab during construction.
Randalstown Forest North Pillbox
Another Type 24 constructed as the same manner as the other two. The context of the original location has now been lost as a result of heavy forestry planting, but the ridge on which the pillbox sits can still be made out in the landscape. 
This pillbox retains an original steel door. It’s unlikey to have provided any real ballistic protection, but more for the security of the box when not occupied. A bolt on the exterior of the door is testament to this, where no internal securing mechanism still remains. 
Inside the pillbox facing the forward three loopholes. A pile of metalwork on the floor is what remains of the shutters that would have been fitted on rails on the inside of the box. 
Facing the full height door to the rear of the box. A wooden frame on the inside of the box may have held a wood covering and acted as an anti-ricochet material and also helped dampen the sound of multiple machine guns firing simulatneously. 
Detail of the roof slab. A light impression of the brock column can be seen in the right half of the image, along with what appears to be a tar covering. This may have been used to prevent the moisture from the concrete soaking into the material laid on top of the wooden shuttering for pouring the roof piece. The two distinct tones of colour in the concrete suggest the roof slab may have been cast in two sections.
Protective Shutters
Looking through the metal debris on the floor it was possible to make out a number of the steel panels or shutters that would have reduced the aperture of the loopholes. An item that I haven’t seen before is also on the floor and this may have been an open frame used to fire through. As there are no supports internally for the tripod of bipod of a machine gun, this section may have helped give rudimentary support when the gun was firing.
Randalstown Forest South Pillbox
An identical design and construction to the other two pillboxes, this one has been constructed in a rath which may have privided it some obfiscation from view, but the circular earth bank could also have acted as a defensive position for infantry protecting the pillbox. 
Through the rear entrance of the pillbox the central column is visible. Evidence remains in the other two, but it is intact in this position. 
The front loopholes of the pillboxes, with steel fixing in the precast concrete lintel. Screw holes can also be seen below each loophole, likely for a wooden shelf to support a Bren bipod. 
The central column which may have been added to support the roof during casting. 
Unique to Randalstown pillboxes (in my experience) are the floors laid in red brick. Possibly as an economy measure to reduce the amount of concrete used.
Shelf Fixtures
Under each loophole across the Randalstown pillboxes are a pair of three holes. These were probably to support a wooden bench on which the bipod legs of a Bren machine-gun would have been rested. 
A mock-up of what the loophole may have looked like with steel shutters fitted and a wooden shelf. 
Inside this pillbox at RAF Staverton in Gloucestershire the steel shutters and benches remain. While both are a different design, this is a good representation of a typical pillbox interior.
Conclusions
This trio of pillboxes south of Randalstown has been a real pleasure to visit and research. They appear to sit in their original context within the landscape, which is rare. I am confident in my hypothesis that they were sited here to establish a bridgehead a protect a vital bridge crossing over the River Maine after all other bridges had been intentionally demolished and denied to the invaders. While mostly sitting as shells of their former being, tantalising clues remain about their fixtures and fittings; steel doors, internal steel shutters and wooden shelves. However, the intense planting of trees throughout the forest has likely destroyed any other field defences that may have been constructed.
All but one of these pillboxes can be visited on a visit to Randalstown Forest, and armed with a bit of this background information I am sure you can start to appreciate the landscape as it would have appeared in 1941 as the Nation prepared to defend until the end.
- 1A programme of defence building was undertaken by the Irish along the River Boyne and around a number of south coast ports
- 2Preparations for war had been undertaken during the preceding years including the development of new aircraft, research into early warning systems and civil contingent planning.
- 3British planning and preparations to resist invasion on land, September 1939 – September 1940. Newbold, David John, 1988
- 4Military Training Pamphlet, No. 46, Camoflague, Part 2, Field Defences, 1941.
- 5Northern Ireland in the Second World War, John W. Blake, Chapter V: the Threat of Invasion, Section 2, footnotes
- 6Royal Engineers Pocket Book, Chapter IV Defences, 1936. They would have required 800 long pickets, 1600 short pickets, 130 coils of barbed wire and three 3-ton trucks.
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- 9Pillboxes of Britain and Ireland, Mike Osborne, 2008 (2012 reprint)