The Ruck machine gun post or Ruck pillbox is a type of hardened field fortification built in Britain during the
invasion crisis of 1940–1941. It was designed by James Ruck and was made from
prefabricated concrete sections and
paving slabs,
sandbag
A sandbag or dirtbag is a bag or sack made of hessian (burlap), polypropylene or other sturdy materials that is filled with sand or soil and used for such purposes as flood control, military fortification in trenches and bunkers, shielding gl ...
s and
rammed earth
Rammed earth is a technique for constructing foundations, floors, and walls using compacted natural raw materials such as earth, chalk, lime, or gravel. It is an ancient method that has been revived recently as a sustainable building method ...
.
[Machine gun posts constructed from hollow concrete blocks ]
HO 197/8
The National Archives
National archives are central archive, archives maintained by countries. This article contains a list of national archives.
Among its more important tasks are to ensure the accessibility and preservation of the information produced by government ...
The Ruck machine gun post was relatively widely used in Lincolnshire and along the east coast of England, but is now extremely rare with just a handful of extant examples. Today, just five Ruck machine gun post sites are recorded in the Defence of Britain database.
Design
James Ruck was the north midlands regional works adviser to the
Ministry of Home Security
The Ministry of Home Security was a British government department established in 1939 to direct national civil defence, primarily tasked with organising air raid precautions, during the Second World War. The Ministry for Home Security was headed ...
. His principal duties related to the provision of air-raid shelters. In June 1940, he offered the military a design for a machine gun post:
Ruck's design was based on precast half-arch concrete sections produced by Hydroprest Concrete Ltd at
Scunthorpe
Scunthorpe () is an Industrial city, industrial town and unparished area in the Unitary authorities of England, unitary authority of North Lincolnshire in Lincolnshire, England of which it is the main administrative centre. Scunthorpe had an es ...
.
Four sections formed an arch with inside dimensions wide, high and long. Any number of the arches could be assembled together to form a structure of a desired length, but for Ruck's design 20-inch gaps between the arches would be left to serve as
embrasure
An embrasure (or crenel or crenelle; sometimes called gunhole in the domain of gunpowder-era architecture) is the opening in a battlement between two raised solid portions ( merlons). Alternatively, an embrasure can be a space hollowed ou ...
s, with an inside length of . The arches were clad with two layers of mortar and concrete paving slabs; this filled in the gaps except where an embrasure was required and gave a wall thickness that varied between . The ends were walled up with hollow concrete blocks filled with bricks; the wall at one end had an embrasure, the other end had an entrance. The concrete offered only limited protection, so the structure would be partly buried and then surrounded by an outer wall of sandbags to the level of the embrasures and the gap between the wall and the concrete filled with rammed earth.
According to Ruck, who enthusiastically promoted his design, the principal advantages of the machine gun post were that it could be quickly constructed by unskilled labour and made economical use of materials. The precast components could be produced at the rate of 70 posts per day and Ruck claimed that six unskilled men could complete three precast units in a day.
Ruck also emphasised that his design made use of "some hundreds of thousands of tons of this material lying in stocks in makers yards throughout the country requiring no fresh drain on cement or steel".
Ruck estimated the cost of a post to be just £40
quivalent to £ in
Construction

In July 1940, instructions were issued for the order of 1,600 posts,
by September 1940 some 4,000 posts had been constructed and there were orders for a further 2,000.
Today, the Ruck machine gun post presents something of a mystery. Despite the substantial numbers constructed, traces of them are rare – just 5 were recorded by the Defence of Britain project.
Of all the pillbox designs, the Ruck machine gun post is one of the most readily disassembled and this may have been the fate of many of these posts. Because the post had to be partially buried, it was best employed on rising ground;
it may be that many were deployed in soft cliffs and dunes along an ever-changing coastline and have been lost to erosion.
Finally, there may be extant examples that are simply unrecognised for what they are.
See also
*
British anti-invasion preparations of World War II
British anti-invasion preparations of the Second World War entailed a large-scale division of military and civilian mobilisation in response to the threat of invasion ( Operation Sea Lion) by German armed forces in 1940 and 1941. The British A ...
*
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'', a reference to their shape.
Design and development
In M ...
Notes
References
*
External links
*
*
{{Use British English, date=October 2010
World War II military equipment of the United Kingdom
20th-century forts in England