British anti-invasion preparations of World War II

British anti-invasion preparations of World War II entailed a large-scale division of military and civilian mobilization in response to the threat of invasion by German armed forces in 1940 and 1941. The army needed to recover from the defeat of the British Expeditionary Force in France, and 1.5 million men were enrolled as part-time soldiers in the Home Guard. The rapid construction of field fortifications transformed much of Britain, especially southern England, into a prepared battlefield. Short of heavy weapons and equipment, the British had to make the best use of whatever was available.

The German invasion plan, Operation Sealion, was never taken beyond the preliminary assembly of forces. Today, little remains of Britain's anti-invasion preparations. Only reinforced concrete structures such as pillboxes are common, and until recently, even these have been unappreciated as historical monuments.

Political and military background

On 1 September 1939, Germany invaded Poland; two days later, Britain and France declared war on Germany, launching World War II. Within three weeks, the Red Army of the Soviet Union invaded the eastern regions of Poland in fulfillment of the secret Molotov-Ribbentrop Pact with Germany. A British Expeditionary Force (BEF) was sent to the Franco-Belgian border, but Britain and France did not take any direct action in support of the Poles. By 1 October, Poland had been completely overrun.

There was little fighting over the months that followed. In a period known as the Phoney War, French and British soldiers trained for war and constructed and manned defences on the eastern borders of France.

On 9 April 1940, Germany invaded Denmark and Norway. This operation preempted the perceived British plan to invade Norway for protective purposes. [ [http://www.yale.edu/lawweb/avalon/imt/proc/juddenma.htm War crimes trial judgement on the invasion of Norway] , via the Avalon Project- accessed 2008-01-14] Denmark surrendered immediately, and after fierce fighting, Norway also fell. The invasion of Norway was a combined forces operation in which the German war machine projected its power across the sea; this German success would come to be seen by the British as a dire portent. [MacKenzie, 1995, p20.]

On 7 May and 8 May 1940, in the British House of Commons, the Norway Debate revealed intense dissatisfaction with and outright hostility toward the government of Prime Minister Neville Chamberlain. Two days later, with events moving swiftly, Chamberlain resigned and was succeeded by Winston Churchill.

On 10 May 1940, Germany invaded France. By that time, the BEF consisted of 10 infantry divisions in three corps, a tank brigade and a Royal Air Force detachment of around 500 aircraft. The BEF was pinned by a German diversionary attack through Belgium and then isolated by the main attack that came through the Ardennes forest. Well-equipped and highly mobile "Panzer" divisions of the "Wehrmacht" easily overran the prepared defences, another painful lesson. There was some fierce fighting, but most of the BEF withdrew to a small area around the French port of Dunkirk.

As things had gone badly for the allies in France, it became evident that some thought needed to be given to the possibility of having to resist an attempted invasion of Britain by German forces.

British armed forces

British Army

The evacuation of British and French forces (Operation Dynamo) began on 26 May with air cover provided by the RAF at heavy cost. Over the following ten days, 338,226 French and British soldiers were evacuated to Britain. Most of the personnel were brought back to Britain, but many of the army's vehicles, tanks, guns, ammunition and heavy equipment and the RAF's ground equipment and stores were left behind in France. [cite web | title=On This Day: June 4th 1940 | work=BBC | url=http://news.bbc.co.uk/onthisday/hi/dates/stories/june/4/newsid_3500000/3500865.stm | accessdate=2006-07-28] Some soldiers returned even without their rifles.

In June 1940 the British Army had 22 infantry divisions and one armoured division. The infantry divisions were, on average, at half strength, had only one-sixth of their normal artillery, [Lowery, 2004, p11.] and were almost totally lacking in transport. There was a critical shortage of ammunition such that none could be spared for practice. [MacKenzie, 1995, p52.] VII Corps was formed to control the Home Forces' general reserve, and included the 1st Armoured Division.

Home Guard

On 14 May 1940, Secretary of State for War Anthony Eden announced the creation of the Local Defence Volunteers (LDV)—later to become known as the Home Guard. The announcement was met with enthusiasm and far more men volunteered than the government expected; by the end of June, there were nearly 1.5 million volunteers. There were plenty of personnel for the defence of the country, but there were no uniforms (a simple armband had to suffice) and equipment was in critically short supply. At first, the Home Guard was armed with whatever was available: guns in private ownership, a knife or bayonet on a pole, Molotov cocktails and improvised flamethrowers. [cite web | title=Nuttall Flame Thrower | work=The History of Wolverhampton - The City and its People | url=http://www.wolverhamptonhistory.org.uk/people/at_war/ww2/fighting3 | accessdate=2006-07-28] [cite web | title=Colour movie of Home Guard training including an improvised flamethrower | work=Britons at War | url=http://www.nationalmediamuseum.org.uk/Learning/britonsatwar/detail.asp?id=37&topicnum=1 | accessdate=2006-07-28]

By July 1940 the situation had improved somewhat with uniforms, a modicum of training and the arrival of hundreds of thousands of rifles and millions of rounds of ammunition from the USA.Evans, 2004, p68.] New weapons were developed that could be produced cheaply without consuming materials that were needed to produce armaments for the regular units. An early example was the No 76 Special Incendiary Grenade (a glass bottle filled with highly flammable material of which more than six million were made), [MacKenzie, 1995, p92.] and the No. 73 Grenade (an anti-tank grenade resembling a Thermos flask).

The sticky bomb was a glass flask filled with nitroglycerin and given an adhesive coating allowing it to be glued to a passing vehicle. In theory, it could be thrown, but in practice it would most likely need to be placed—thumped against the target with sufficient force to stick—requiring courage and good fortune to be used effectively. An order for one million sticky bombs was placed in June 1940, but various problems delayed their distribution in large numbers until early 1941, and it is likely that fewer than 250,000 were produced. [National Archive, WO 185/1, Anti-tank measures Sticky Bomb adoption and production.]

A measure of mobility was provided by bicycles, motorcycles, private vehicles and horses. A small number of units were equipped with armoured cars, some of which were of standard design, but many were improvised locally from commercially available vehicles by the attachment of steel plates. [Mace, 2001, p92.]

Later in 1941, more sophisticated weapons were made available such as the Blacker Bombard anti-tank weapon, the Northover Projector (a black powder powered mortar), and the Smith Gun (a small artillery gun that could be towed by a private motorcar).

Royal Air Force

In mid-1940, the principal concern of the Royal Air Force, together with elements of the Fleet Air Arm, was to contest the control of British airspace with the German Luftwaffe. For the Germans, achieving at least local air superiority was an essential prerequisite to any invasion.

If the German air force had prevailed and attempted a landing, a much-reduced Royal Air Force would have been obliged to operate from airfields well away from the south east of England. Any airfield that was in danger of being captured would have been made inoperable and there were plans to remove all portable equipment from vulnerable radar bases and completely destroy anything that could not be moved. Whatever was left of the RAF would have been committed to intercepting the invasion fleet in concert with the Royal Navy—to fly in the presence of an enemy that enjoys air superiority is very dangerous. However, the RAF would have kept several advantages, such as being able to operate largely over friendly territory, as well as having the ability to fly for longer as, until the Germans were able to operate from airfields in England, "Luftwaffe" pilots would still have to fly significant distances to reach their operational area.

Every available aircraft was to be committed to the defence. In the event of invasion almost anything that was not a fighter would be converted to a bomber—student pilots, some in the very earliest stages of training, would use around 350 Tiger Moth and Magister trainers to drop convert|20|lb|abbr=on bombs from rudimentary bomb racks. [Cox, 1974, p149.]

Shortly before the outbreak of World War II the Chain Home radar system began to be installed in the south of England, with three radar stations being operational by 1937. [cite web| url=http://www.undiscoveredscotland.co.uk/usbiography/vwxy/robertwatsonwatt.html |title=Undiscovered Scotland - Robert Watson-Watt | work= | accessdate=2007-04-16] [cite web| url=http://www.undergroundkent.co.uk/swingate_chain_home_station.htm | title=Undergroundkent.co.uk - Swingate Chain Home Station | work= | accessdate=2007-04-16] Although the German High Command suspected that the British may have been developing these systems, Zeppelin test flights had proved inconclusive. As a result the expanding Chain Home radar system, and aircraft-based radar first fielded in 1940, became a vital piece of Britain's defensive capabilities during the Battle of Britain.

Royal Navy

The British Home Fleet was a force that dwarfed anything the Kriegsmarine could put to sea. On 1 July, one cruiser and 23 destroyers were committed to escort duties in the Western Approaches, plus 12 destroyers and one cruiser on the Tyne and the aircraft carrier "Argus". More immediately available were ten destroyers at the south coast ports of Dover and Portsmouth, a cruiser and three destroyers at Sheerness on the River Thames, three cruisers and seven destroyers at the Humber, 9 destroyers at Harwich, and two cruisers at Rosyth. The rest of the Home Fleet—five battleships, three cruisers and nine destroyers—was based far to the north at Scapa Flow. There were, in addition, many corvettes, minesweepers, and other small vessels. [James, 2006, p39. Brian James notes that while the Germans had four minelayers in their western fleet, the British had 52 minesweepers and 16 minesweeping trawlers.] By the end of July, a dozen additional destroyers were transferred from escort duties to the defence of the homeland, and more would join the Home Fleet shortly after. [Evans, 2004, p69.]

Field fortifications

The British engaged upon an extensive programme of field fortification.

On 27 May 1940 a Home Defence Executive was formed under General Sir Edmund Ironside, Commander-in-Chief Home Forces, to organise the defence of Britain. At first defence arrangements were largely static and focused on the coastline (the coastal crust) and, in a classic example of defence in depth, on a series of inland anti-tank 'stop' lines. The were designated Command, Corp and Divisional according to their status. The longest and most heavily fortified was the General Headquarters anti-tank line, GHQ Line, which ran across southern England, wrapped around London and then ran north to Yorkshire. It was intended to protect the capital and the industrial heartland of England. Another major line was the Taunton Stop Line, which defended against an advance from England's south-west peninsula. London and other major cities were ringed with inner and outer stop lines. Some 50 stop lines were constructed, but not all were completed.

Military thinking shifted rapidly. Given the lack of equipment and properly trained men, Ironside had had little choice but to adopt a strategy of static warfare, but it was soon perceived that this would not be sufficient. Ironside has been criticised for having a siege mentality, but some consider this unfair as he is believed to have understood the limits of the stop lines and never expected them to hold out indefinitely. [Foot, 2006, p12–13.] [Churchill, 2005, p155.]

However, Prime Minister Churchill was not satisfied with Ironside's progress especially with regard to the creation of a mobile reserve. Anthony Eden, the Secretary of State for War, suggested that Ironside should be replaced by General Brooke (later Lord Alanbrooke). On 17 July 1940 Churchill spent an afternoon with Brooke [Alanbrooke, 2001. Entry 17 July 1940.] and was soon convinced that they were in close agreement as to how best to defend the nation. On 19 July Brooke replaced Ironside. [Churchill, 2005, p233–234. Churchill's account suggests that the afternoon meeting and Brooke's promotion occurred on the same day, but, Brooke's diary entry indicates a two-day delay.]

Brooke's appointment coincided with more trained men and better equipment becoming available. Under Brooke new strategies and tactics were devised. More concentration was placed on defending the coastal crust and inland a hedgehog defence strategy of defended localities and anti-tank islands was established, each having all-round defence. Many of these anti-tank islands were established along the already constructed stop lines where existing defences could be integrated into the new strategy and, especially, at towns and villages where there was a Home Guard to provide personnel.

Coastal crust

Any German invasion of Britain would have to involve the landing of troops and equipment somewhere on the coast, and the most vulnerable areas were the south and east coasts of England. Here, Emergency Coastal Batteries were constructed to protect ports and likely landing places. They were fitted with whatever guns were available which mainly came from naval vessels scrapped since the end of the First World War. These included 6 inch (152 mm), 5.5 inch (140 mm), 4.7 inch (120 mm) and 4 inch (102 mm) guns. These had little ammunition, sometimes as few as ten rounds apiece. At Dover, two 14 inch (356 mm) guns known as Winnie and Pooh were employed. [Evans, 2004, p59.] Dover Castle had been a naval fort since World War I and had two convert|9.2|in|mm|sing=on guns and four convert|6|in|mm|sing=on guns after modernisation in the late 1920s.Fact|date=June 2007 There were also a small number of land based torpedo launching sites. [cite web| url=http://www.nci-frowardpoint.org.uk/sitehistory.htm | title=Froward Point Team, Kingswear, Devon - site history | work=National Coastwatch | accessdate=2007-02-19]

Beaches were blocked with entanglements of barbed wire, usually in the form of three coils of concertina wire fixed by metal posts, or a simple fence of straight wires supported on waist-high posts. [Ruddy, 2003, p24.] The wire would also demarcate extensive minefields, with both anti-tank and anti-personnel mines on and behind the beaches. On many of the more remote beaches this combination of wire and mines represented the full extent of the passive defences.

Portions of the Romney Marsh, which was the planned invasion site of Operation Sealion, were flooded [Gowdin & Ingrams, "Romney Marsh", p107.] and there were plans to flood more of the Marsh if the invasion were to materialise. [ [http://www.bbc.co.uk/ww2peopleswar/stories/83/a4967283.shtml BBC - WW2 People's War - Improvisation Sir ] ]

Piers, ideal for landing of troops, and situated in large numbers along the south coast of England, were disassembled, blocked or otherwise destroyed. Many piers were not repaired until the late 1940s or early 1950s. [cite web| url=http://www.guardian.co.uk/uk_news/story/0,3604,953927,00.html | title= Arson fear as Brighton pier burns again | work=www.guardian.co.uk |caccessdate=2007-04-16]

Where a barrier to tanks was required, beach scaffolding (also known as Admiralty Scaffolding or obstacle Z1 [Some sources refer to obstacle 2.1, but this is probably a misprint] ) was constructed. Essentially, this was a fence of scaffolding tubes 9 feet (3 m) high and was placed at low water so that tanks could not get a good run at it. [Ruddy, 2003, p25.] Beach scaffolding was deployed along hundreds of miles of vulnerable beaches. [cite web| url=http://s134542708.websitehome.co.uk/pillboxes/html/beach_scaffolding_0.html | title=Extant beach scaffolding, Lunan bay, Angus | work=Pillbox UK, Photograph by Anne Burgess | accessdate=2006-06-22]

An even more robust barrier to tanks was provided by long lines of anti-tank cubes. The cubes were made of reinforced concrete 5 feet (1.5 m) to a side. Thousands were cast "in situ" in rows sometimes two or three deep.

The beaches themselves were overlooked by pillboxes of various types (see British hardened field defences of World War II). These were sometimes placed low down to get maximum advantage from enfilading fire whereas others were placed high up making them much harder to capture. Searchlights were installed at the coast to illuminate the sea surface and the beaches for artillery fire. [Ruddy, 2003, p22, Beach Light.] [cite web| url=http://s134542708.websitehome.co.uk/pillboxes/html/beach_defence_light.html | title=Beach Defence Light | work=Pillboxes UK | accessdate=2006-07-09] [cite web| url=http://www.users.globalnet.co.uk/~rwbarnes/defence/guest/casl-.htm | title=Restored Coastal Artillery Searchlight, Weymouth | work= | accessdate=2006-07-16]

Many small islands and peninsulas were fortified to protect inlets and other strategic targets. In the Firth of Forth in east central Scotland, Inchgarvie Island was heavily fortified with several gun emplacements, which can still be seen. This provided invaluable defence from seaborne attacks on the Forth Bridge and Rosyth Dockyard, [cite web| url=http://www.geo.ed.ac.uk/scotgaz/features/featurefirst1302.html | title=Overview of Inchgarvie Island from Edinburgh University Geography Department's Gazetteer for Scotland | work= | accessdate=2007-04-13] approximately a mile upstream from the bridge. Further out to sea, Inchmickery Island, convert|1.6|mi|km north of Edinburgh, was similarly fortified. The remnants of gun emplacements on the coast to the north, in North Queensferry, and south, in Dalmeny, of Inchmickery Island also remain. [cite web| url=http://local.live.com/default.aspx?v=2&cp=55.989455~-3.382531&style=h&lvl=19&tilt=-90&dir=0&alt=-1000&encType=1 | title=Satellite link to gun emplacements on the south bank of the Firth of Forth | work= | accessdate=2007-04-13]

Lines and islands

The primary purpose of the stop lines and the anti-tank islands that followed was to hold up the enemy, slowing progress and restricting the route of an attack. The need to prevent tanks from breaking through was of key importance. Consequently, the defences generally ran along pre-existing barriers to tanks such as rivers and canals; railway embankments and cuttings; thick woods; and other natural obstacles. Where possible, usually well-drained land was allowed to flood making the ground too soft to support even tracked vehicles. [Wills, 1985, p57.]

Thousands of miles of anti-tank ditches were dug, usually by mechanical excavators, but occasionally by hand. They were typically convert|18|ft|m wide and convert|11|ft|m deep and could be either trapezoidal or triangular in section with the defended side being especially steep and revetted with whatever material was available.Ruddy, 2003, p29.] [cite web| url=http://www.southsomersetmuseums.org.uk/heritage/chard-tankditch.htm | title=Location of anti-tank ditch | work=South Somerset Museums and Heritage Services | accessdate=2007-02-22 A rare extant example.]

Elsewhere, anti-tank barriers were made of massive reinforced concrete obstacles, either cubic, pyramidal or cylindrical. The cubes generally came in two sizes: 5 feet (1.5 m) or 3.5 feet (1 m) high.Ruddy, 2003, p26.] [cite web| url=http://s134542708.websitehome.co.uk/pillboxes/html/cubes_0.html | title=Images of anti-tank cubes.| work=Pillboxes UK | accessdate=2006-07-08] In a few places, anti-tank walls were constructed—essentially continuously abutted cubes [Foot, 2006, p45.]

Large cylinders were made from a section of sewer pipe 3–4 feet (90–120 cm) in diameter filled with concrete typically to a height of 4 to convert|5|ft|m, frequently with a dome at the top. Smaller cylinders cast from concrete are also frequently found. [Ruddy, 2003, p28.] [cite web| url=http://s134542708.websitehome.co.uk/pillboxes/html/cylinders_0.html| title=Images of Anti-tank cylinders | work=Pillboxes UK | accessdate=2006-07-08]

Pimples, popularly known as Dragon's teeth, were pyramids of concrete designed specifically to counter tanks which, attempting to pass them, would climb up exposing vulnerable parts of the vehicle and possibly slip down with the tracks between the points. They ranged in size somewhat, but were typically 2 feet (600 mm) high and about 3 feet (900 mm) square at the base. There was also a conical form. [cite web| url=http://s134542708.websitehome.co.uk/pillboxes/html/dragons_teeth_0.html | title=Images of Anti-tank pimples | work=Pillboxes UK | accessdate=2006-07-08]

Cubes, cylinders and pimples were deployed in long rows, often several rows deep, to form anti-tank barriers at beaches and inland. They were also used in smaller numbers to block roads. They frequently sported loops at the top for the attachment of barbed wire. There was also a tetrahedral or caltrop-shaped obstacle, although it seems these were rare. [cite web| url=http://www.britarch.ac.uk/projects/dob/crom1b.html| title=The 'Caltrop' as Anti-Tank Obstacle | accessdate=2006-03-04]

Where natural anti-tank barriers needed only to be augmented, concrete or wooden posts sufficed. [.]

Roads offered the enemy fast routes to their objectives and consequently they were blocked at strategic points. Many of the roadblocks formed by Ironside were semi-permanent. In many cases, Brooke had these removed altogether, as experience had shown they could be as much of an impediment to friends as to foes. Brooke favoured removable blocks. [Ruddy, 2003, p27.]

The simplest of the removable roadblocks consisted of concrete cylinders of various sizes but typically about 2 feet (600 mm) in diameter and 3 feet (1 m) high; these could be manhandled into position as required. [Lowry, 2004, p25.] However, these would be insufficient to stop armoured vehicles. One common type of removable anti-tank roadblock comprised massive concrete posts permanently installed at the roadside; these posts had holes and/or slots to accept horizontal railway lines or rolled steel joists (RSJs). Similar blocks were placed across railway tracks [.] because tanks can move along tracks almost as easily as they can along roads. These blocks would be placed strategically where it was difficult for a vehicle to go around—anti-tank obstacles and mines being positioned as required—and they could be opened or closed within a matter of minutes. [cite web | title=Imperial War Museum Online Collection | work=Photograph number H 7330, Home Guards erecting a road barrier | url=http://www.iwmcollections.org.uk/qryPhotoImg.asp | accessdate=2006-05-29]

There were two types of socket roadblocks. The first comprised vertical lengths of railway line placed in sockets in the road, was known as "hedgehog". [cite web| url=http://s134542708.websitehome.co.uk/pillboxes/html/hedgehog.html| title=Images of Hedgehog obstacles | work=Pillboxes UK | accessdate=2006-05-24] [cite web | title=Imperial War Museum Online Collection | work=Photograph number H 15191, Home Guard soldiers prepare a roadblock by inserting metal girders into pre-dug holes in the road (image) | url=http://www.iwmcollections.org.uk/qryPhotoImg.asp | accessdate=2007-03-14] The second type comprised railway lines or RSJs bent or welded at around a 60° angle, known as "hairpins".Lowry, 2004, p20.] [cite web| url=http://s134542708.websitehome.co.uk/pillboxes/html/hairpin.html| title=Images of Hairpin obstacles | work=Pillboxes UK | accessdate=2006-06-22] In both cases, prepared sockets about 6 inches (150 mm) square were placed in the road, closed by covers when not in use, allowing traffic to pass normally.

Bridges and other key points were prepared for demolition at short notice by preparing chambers filled with explosives. A Depth Charge Crater was a site in a road (usually at a junction) prepared with buried explosives that could be detonated to instantly form a deep crater as an anti-tank obstacle. The Canadian Pipe Mine (later known as the McNaughton Tube after General Andrew McNaughton) was a horizontally bored pipe packed with explosives—once in place this could be used to instantly ruin a road or runway. [Cameron, 2000, p156.] [cite web| url=http://news.bbc.co.uk/1/hi/england/hampshire/4934102.stm | title=Large bomb found at ex-Navy base | work=BBC News | accessdate=2006-09-03] Prepared demolitions had the advantage of being undetectable from the air—the enemy could not take any precautions against them, or plot a route of attack around them.

Crossing points in the defence network—bridges, tunnels and other weak spots—were called nodes or points of resistance. These were fortified with removable road blocks, barbed wire entanglements, and mines. These passive defences were overlooked by trench works, gun and mortar emplacements, and pillboxes. In places entire villages were fortified using barriers of scaffolding, sandbagged positions and loopholes in existing buildings. [Foot, 2006, p11.]

Nodes were designated 'A', 'B' or 'C' depending upon how long they were expected to hold out. [Foot, 2006, p10.] Home Guard troops were largely responsible for the defence of nodal points and other centres of resistance such as towns and defended villages. Category 'A' nodal points and anti-tank islands usually had a garrison of regular troops.

The rate of construction was frenetic: by the end of September 1940, 18,000 pillboxes and countless other preparations had been completed. [Cruickshank, 2001, p166.]

Airfields and open areas

Open areas were considered vulnerable to invasion from the air: a landing by paratroops, glider-borne troops or even powered aircraft which could land and take off again. Open areas with a straight length of 500 yards (450 m) or more within five miles (8 km) of the coast or an airfield were considered vulnerable. These were blocked by trenches or, more usually, by wooden or concrete obstacles, as well as old cars. [cite web | title=Imperial War Museum Online Collection | work=Photograph number D 4282. Obstacles in a field (image) | url=http://www.iwmcollections.org.uk/qryPhotoImg.asp | accessdate=2006-05-31]

Securing an airstrip would be an important objective for the invader. [Ward, 1997, p65.] Airfields, considered extremely vulnerable, were protected by trench works and pillboxes which face inwards towards the runway, rather than outwards. Many of these fortifications were specified by the Air Ministry and defensive designs were unique to airfields—these would not be expected to face heavy weapons so the degree of protection was less and there was more emphasis on all-round visibility and sweeping fields of fire. It was difficult to defend large open areas without creating impediments to the movement of friendly aircraft. Solutions to this problem included the pop-up Picket Hamilton fort—a light pillbox that could be lowered to ground level when the airfield was in use. [cite web| url=http://www.users.globalnet.co.uk/~rwbarnes/defence/silloth_/phfort-.htm| title=Pickett-Hamilton Fort | accessdate=2006-06-11] [cite web| url=http://s134542708.websitehome.co.uk/pillboxes/html/pickett_hamilton_pillbox.html | title=Picket-Hamilton fort | work=Pillboxes UK | accessdate=2007-03-14]

Another innovation was a mobile pillbox that could be driven out onto the airfield, this was known as the Bison and consisted of a lorry with a concrete armoured cabin and a small concrete pillbox on the flat bed. [cite web| url=http://s134542708.websitehome.co.uk/pillboxes/html/bison_pillbox.html | title=Bison mobile pillbox | work=Pillboxes UK | accessdate=2007-03-14] [cite web| url=http://www.warwheels.net/ThorneycroftBisonBovingtonTROWBRIDGE.html | title=Thorneycroft Bison | work=War Wheels.net | accessdate=2007-03-14] Constructed in Canada, a 'runway plough', assembled in Scotland, survives at Eglinton Country Park. It was purchased by the army in WWII to rip up aerodrome runways and railway lines if an invasion took place. It was used at the old Eglinton Estate, which had been commandeered by the army, to provide its army operators with the necessary experience. It was hauled by a powerful Foden Trucks tractor, possibly via a pulley and cable system.Eglinton Country Park archive.]

Hardened field defences

The field fortifications constructed throughout Britain included large numbers of hardened field defences: mostly in the form of pillboxes. [cite web| url=http://www.britarch.ac.uk/projects/dob/map.html | title=Map of anti-invasion defences | work=Defence of Britain Project | accessdate=2007-04-18]

In May 1940, the Directorate of Fortifications and Works (FW3) was set up at the War Office. 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 pillboxes, 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. [Some commentators make reference to the Ordnance QF 6 pounder rather than the older Hotchkiss 6pdr, but this is an error.]

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.

A small number of pillboxes had been constructed in the First World War and where possible these were integrated into the defence plans. Some pillboxes may predate the publication of the FW3 designs, but in any case some local commanders introduced modifications to the standard FW3 designs or introduced designs of their own. These non-standard design pillboxes may be produced in some numbers or completely "ad hoc" designs suited to local conditions. Other designs were produced as commercial ventures.

Other defensive measures

Other basic defensive measures included the removal of signposts, milestones (some had the carved details obscured with cement) and railway station signs making it more likely that an enemy would become confused. [cite web | title=Imperial War Museum Online Collection | work=Photograph number HU 49250, A signpost in Surrey being dismantled (image) | url=http://www.iwmcollections.org.uk/qryPhotoImg.asp | accessdate=2006-05-29] Pumps were removed from service stations near the coast and there were careful preparations for the destruction of those that were left lest they prove useful to the invader.Evans, 2004, p64.] Detailed plans were made for the destruction of anything that might prove useful to the invader such as port facilities, key roads and rolling stock. [Churchill, 2005, p156.]

In certain areas non-essential citizens were evacuated. In the county of Kent, 40% of the population was relocated; in East Anglia, the figure was 50%.

Perhaps most importantly, the population was told what was expected from them. In June 1940, the Ministry of Information published "If the Invader Comes, what to do—and how to do it", [Lowry, 2004, p43.] [cite web| url=http://www.swanseaheritage.net/article/gat.asp?ARTICLE_ID=1865&PRIMARY_THEME_ID=3| title=If the Invader Comes, leaflet | accessdate=2006-05-15] it began:

The first instruction given quite emphatically is that, unless ordered to evacuate, "THE ORDER IS 'STAY PUT' " [capitalisation as in original] . The roads were not to be blocked by refugees. Further warnings were given not to believe rumours and not to spread them, to be distrustful of orders that might be faked and even to check that an officer giving orders really is British. Further: keep calm and report anything suspicious quickly and accurately; deny useful things to the enemy such as food, fuel, maps or transport; be ready to block roads—when ordered to do so—"by felling trees, wiring them together or blocking the roads with cars"; to organise resistance at shops and factories; and, finally:

:"THINK BEFORE YOU ACT. BUT THINK ALWAYS OF YOUR COUNTRY BEFORE YOU THINK OF YOURSELF."
[Capitalisation as in original]

On 13 June 1940 the ringing of church bells was banned; henceforth they would only be rung by the military or the police to warn that an invasion—generally meaning by parachutists—was in progress. [Fleming, 1957, p96.]

In 1941, in towns and villages invasion committees were formed to cooperate with the military and plan for the worst should their communities be isolated or occupied. [cite web | title=Imperial War Museum Online Collection | work=Photograph number D 4847, Village Invasion Committee meeting (image) | url=http://www.iwmcollections.org.uk/qryPhotoImg.asp | accessdate=2006-05-29] The members of committees typically included representatives of the local council, the Air Raid Precautions service, the fire service, the police, the Women’s Voluntary Service and the Home Guard, as well as officers for medicine, sanitation and food. Plans of these committees were kept in secret "War Books" although few remain. Detailed inventories of anything useful were kept: vehicles, animals and basic tools, and lists were made of contact details for key personnel. Plans were made for a wide range of emergencies, including improvised mortuaries and places to bury the dead. [cite web| url=http://www.britannia.com/lympstone/warbook.html | title=The History of WWII Invasion Committee "War Books" | author=Ian F Angus | accessdate=2006-07-29] Instructions to the Invasion Committees stated: "...every citizen will regard it as his duty to hinder and frustrate the enemy and help our own forces by every means that ingenuity can devise and common sense suggest." [Consolidated Instructions to Invasion Committees, 1942, p19.]

It is clear that more than merely passive resistance was expected—or at least hoped for—from the population. Churchill considered the formation of a Home Guard Reserve, given only an armband and basic training on the use of simple weapons such as Molotov cocktails. The reserve would only have been expected to report for duty in an invasion. [Churchill, 2005, p582.] Later, Churchill wrote how he envisaged the use of the sticky bomb: "We had the picture in mind that devoted soldiers "or civilians" would run close up to the tank and even thrust the bomb upon it, though its explosion cost them their lives [Italics added for emphasis] ." [Churchill, 2005, p149.] He also later recorded how he intended to use the slogan "You can always take one with you." [Churchill, 2005, p246.]

Guns, petroleum and poison

In 1940, weapons were critically short; there was a particular scarcity of anti-tank weapons, many of which had been left in France. Ironside had only 170 2-pounder anti-tank guns, but these were supplemented by 100 Hotchkiss 6-pounder guns dating from World War I, [Foot, 2006, p7.] improvised into the anti-tank role by the provision of solid shot. By the end of July 1940, an additional 900 75 mm field guns had been received from the USA, [Churchill, 2005, p238.] —the British were desperate for any means of stopping armoured vehicles.

One of the few resources not in short supply was petroleum oil; supplies intended for Europe were filling British storage facilities. [Banks, 1946, p27.] Considerable effort and enthusiasm was put into making use of petroleum products as a weapon of war. The Army had not had flame throwers since the First World War, but a significant number were improvised from pressure greasing equipment acquired from automotive repair garages. Although limited in range, they were reasonably effective. [White, 1955, p16.]

There were many ideas for using petroleum on a larger scale and although many proved fruitless a number of practical weapons were developed.

A mobile flame trap comprised surplus bulk storage tanks on trucks, the contents of which could be hosed into a sunken road and ignited. A static flame trap was prepared with perforated pipes running down the side of a road connected to a convert|600|impgal|L USgal|-1|sing=on|lk=on elevated tank. Usually gravity sufficed but in a few cases a pump assisted in spraying the mixture of oil and petrol. [Hayward, 2001, p15–17.]

A flame fougasse comprised a 40 gallon light steel drum [Although the standard capacity is 44 imperial gallons, historical records generally refer to 40-gallon drums.] filled with petroleum mixture and a small, electrically detonated explosive. This was dug into the roadside with a substantial overburden and camouflaged. Ammonal provided the propellant charge, it was placed behind the barrel and, when triggered, caused the barrel to rupture and shoot a flame 10 feet (3 m) wide and 30 yards (30 m) long. [Barrel Flame Traps, 1942.] [cite web | title=WW2 People's War (BBC) | work=Recollections of Fred Lord Hilton MM - witness to a flame fougasse demonstration | url=http://www.bbc.co.uk/ww2peopleswar/stories/71/a8090471.shtml | accessdate=2006-06-01] They were usually deployed in batteries of four barrels [Evans, 2004, p62.] and would be placed at a location such as a corner, steep incline or roadblock where vehicles would be obliged to slow. [cite web | title=Flame Fougasse (surviving remains) | work=Pillbox Study Group | author = Adrian Armishaw | url=http://www.pillbox-study-group.org.uk/poyningsflametrappage.htm | accessdate=2008-01-15]

Variants of the flame fougasse included the demigasse, a barrel on its side and left in the open with explosive buried underneath; and the hedge hopper: a barrel on end with explosive buried underneath a few inches deep and slightly off centre. On firing, the hedge hopper barrel was projected ten feet (3 m) into the air and over a hedge or wall behind which it had been hidden. [Hayward, 2001, p19.] [cite web | title=Memoirs of William Leslie Frost, a member of the Home Guard who recalled the hedge hopper weapon in action | work=South Staffordshire Home Guard website | url=http://www.staffshomeguard.co.uk/DotherReminiscences3staffshg.htm | accessdate=2006-07-16] 50,000 flame fougasse barrels were installed at 7,000 sites mostly in southern England and at a further 2,000 sites in Scotland. [Banks, 1946, p38.]

Early experiments with floating petroleum on the sea and igniting it were not entirely successful: the fuel was difficult to ignite, large quantities were required to cover even modest areas and the weapon was easily disrupted by waves. However, the potential was clear. By early 1941 a flame barrage technique was developed. Rather than attempting to ignite oil floating on water, nozzles were placed above high-water mark with pumps producing sufficient pressure to spray fuel which produced a roaring wall of flame over, rather than on, the water. [Cameron, 2000, pp163–164.] Such installations consumed considerable resources and although this weapon was impressive, its network of pipes was vulnerable to pre-landing bombardment; General Brooke did not consider it effective. [Alanbrooke, 2001. Entry 24 February 1941.] Initially ambitious plans were cut back to cover just a few miles of beaches. [Hayward, 2001, p19–25.] [cite web | title=Imperial War Museum Online Collection | work=Images of petroleum warfare, search for "Fougasse" | url=http://www.iwmcollections.org.uk/qryPhotoImg.asp | accessdate=2006-05-29]

It seems likely the British would have used poison gas against troops on beaches. General Brooke, in an annotation to his published war diaries, stated that he "...had every intention of using sprayed mustard gas on the beaches". [Alanbrooke, 2001. Entry 22 July 1940.] Mustard gas was manufactured as well as chlorine, phosgene and Paris Green. Poison gases were stored at key points for use by Bomber Command and in smaller quantities at many more airfields for use against the beaches. Bombers and crop sprayers would spray landing craft and beaches with mustard gas and Paris Green. [cite web| url=http://www.bpears.org.uk/Misc/War_NE/w_section_05.html | title=Rowlandds Gill and the North-East, 1939–1945 | work=Chapter 5: Invasion | author=Brian Pears | accessdate=2006-07-28] [Ward, 1997, p83.] [cite web| url=http://www.rafmuseum.org/london/collections/aircraft/de-havilland-tiger-moth-ii.cfm | title=de Havilland Tiger Moth II | work= RAF Museum, London | author= | accessdate=2008-06-18]

Deception and disinformation

In addition to hiding real weapons and fortifications, steps were taken to create the impression of the existence of defences that were not real. Drain pipes stood in place of real guns, [cite web | title=WW2 People's War (BBC) | work=Recollections of Mike Stapleton | url=http://www.bbc.co.uk/ww2peopleswar/stories/33/a4038833.shtml | accessdate=2006-06-01] dummy pillboxes were constructed, [Wills, 1985, p63.] [cite web | title=Imperial War Museum Online Collection | work=Photograph number F 4022, Dummy pillbox constructed in France | url=http://www.iwmcollections.org.uk/qryPhotoImg.asp | accessdate=2006-05-29] and uniformed mannequins kept an unblinking wict|vigil. [Cox, 1974, plate p 94.]

Volunteers were encouraged to use anything that would delay the enemy. A young member of the Home Guard (LDV) recalled:

In 1938, a section funded by MI6 was created for propaganda, headed by Sir Campbell Stuart. It was allocated premises at Electra House and was dubbed Department EH. On 25 September 1939 the unit was mobilised to Woburn Abbey [cite web | title=The Major Developments In Political Warfare Through The War, 1938–1945 (typeset from National Archive CAB 101/131) | year = 1949 | author = Y. M. Streatfield | work=PsyWar.org | url=http://www.psywar.org/psywar/reproductions/pwe_report.pdf | accessdate=2007-07-14|format=PDF] where it joined a subversion team from MI6, known as Section D, and by July these teams became a part of the newly created Special Operations Executive (SOE). [Hayward, 2001, p40–45.] These SOE elements went on to form the core of the Political Warfare Executive in 1941. Their task was to spread false rumours and conduct psychological warfare. Inspired by a demonstration of petroleum warfare, one false rumour stated that the British had a new bomb: dropped from an aircraft, it caused a thin film of volatile liquid to spread over the surface of the water which it then ignited. [White, 1955, chapter 1.] Such rumours were credible and rapidly spread. American broadcaster William Shirer recorded large numbers of burns victims in Berlin; though it is not clear what he personally saw, it seems likely his reports were influenced by rumours. The interrogation of a Luftwaffe pilot revealed the existence of such weapons was common knowledge, [cite web | title=Whispers of War - The British World War II rumour campaign | work=Lee Richards | url=http://www.psywar.org/sibs.php | accessdate=2006-05-31] and documents found after the war showed the German high command were deceived. [cite web | title=Deception and Disinformation | work=Herb Friedman | url=http://www.psywarrior.com/DeceptionH.html | accessdate=2006-05-31] The rumour seemed to take on a life of its own on both sides leading to persistent stories of a thwarted German invasion, in spite of official British denials. [Churchill, 2005, p275.] [Hayward, 2001.] [Gillies, 2006, p293–294.] On 15 December 1940, "The New York Times" ran a story claiming that tens of thousands of German troops had been 'consumed by fire' in two failed invasion attempts. [cite web | title=NAZI INVADERS HELD 'CONSUMED BY FIRE' | work=New York Times 15 December 1940 | url=http://pqasb.pqarchiver.com/nytimes/95789986.html?did=95789986&FMT=ABS&FMTS=AI&date=Dec+15%2C+1940&author=By+BORIS+NIKOLAYEVSKY+North+American+Newspaper+Alliance&pub=New+York+Times++(1857-Current&desc=NAZI+INVADERS+HELD+%27CONSUMED+BY+FIRE%27 | accessdate=2006-05-31]

Planned resistance

Auxiliary Units were a specially trained and secret organisation that, in an invasion, would provide resistance behind enemy lines. [Ward, 1997, Chapter 2.] Selected for aptitude and local knowledge, men were mostly recruited from the Home Guard—which also provided a cover for their existence. Organised into patrols of 4 to 8 men: each patrol was a self-contained cell, expected to be self-sufficient. Each patrol was provided with a concealed underground operational base, usually built in woodland and camouflaged. [cite web | title=Parham Airfield Museum | work=The Museum of the British Resistance Organisation | url=http://www.btinternet.com/~david.waller/BROmuseum.htm | accessdate=2006-06-11] [cite web | title=The British Resistance Movement, 1940–44 | work=Geoffrey Bradford | url=http://www.btinternet.com/~david.waller/gbradfordintro.htm | accessdate=2006-06-11]

Auxiliary Units were well-equipped and supplied with food for 14 days.

In addition, a network of civilian Special Duties personnel was recruited to provide an intelligence gathering service, spying on enemy formations and troop movements. Reports were to be collected from dead letter drops and relayed by radio operators of the Royal Signals from secret locations. [cite web | title=The Auxiliary Units | work=Special Duties | url=http://www.warlinks.com/pages/auxiliary.html#special | accessdate=2006-06-11]

The threat recedes

After the evacuation of Dunkirk, people believed that the threatened invasion could come at almost any time. German preparations would require at least a few weeks, but all defensive precautions were made with an extreme sense of urgency. In the summer of 1940, an invasion attempt could occur any time, but some times were rather more likely than others: the phase of the moon, the tides and, most of all, the weather were considerations. The weather deteriorates significantly after September, but an October landing was not out of the question. On 3 October, General Brooke wrote in his diary:

:"Still no invasion! I am beginning to think that the Germans may after all not attempt it. And yet! I have the horrid thought that he may still bring off some surprise on us." [Alanbrooke, 2001. Entry 3 October 1940.]

The Battle of Britain had been won and on 12 October 1940, unknown to the British, Hitler rescheduled Sealion for the spring of 1941. By that spring, the state of Britain’s defences had much improved, with many more trained and equipped men becoming available and field fortifications reaching a high state of readiness. With national confidence rising, the Prime Minister, Churchill, was able to say:

:"We are waiting for the long promised invasion. So are the fishes..." [cite web | title=Dieu Protege la France, Broadcast 21 October 1940 | work=The Churchill Society, London | url=http://www.churchill-society-london.org.uk/LaFrance.html | accessdate=2006-08-07]

When Germany invaded the Soviet Union, on 22 June 1941, it became unlikely that there would be any attempted landing as long as that conflict was undecided—from the British point of view at the time the matter hung in the balance. In July 1941, construction of field fortifications was greatly reduced and concentration given to the possibility of a raid in force rather than a full-scale invasion.

On 7 December 1941, a Japanese carrier fleet launched a surprise air attack on the American fleet at Pearl Harbor; by way of the German declaration of war this brought the USA into the war on Britain’s side and, given America's "Germany first" strategic policy, resources flooded into the UK. After nearly two years of waiting for the enemy, the danger of invasion was finally past.

Would the preparations have been effective?

General Brooke frequently confided his concerns to his private diary. When published, he included additional annotations written many years later:

The question of whether the defences would have been effective in invasion is vexed. In mid-1940, the preparations relied heavily upon field fortifications. The First World War made it clear that assaulting prepared defences with infantry was deadly difficult, but similar preparations in Belgium had been overrun by well-equipped German Panzer divisions in the early weeks of 1940 and with so many armaments left at Dunkirk, British forces were woefully ill-equipped to take on German armour. On the other hand, while British preparations for defence were "ad hoc", so were the German invasion plans: a fleet of 2,000 converted barges and other vessels had been hurriedly made available and their fitness was debatable; in any case, the Germans could not land troops with all their heavy equipment. Until the Germans captured a port, "both" armies would have been short of tanks and heavy guns. [MacKenzie, 1995, p180.]

The later experiences of American forces on Omaha Beach on D-day and taking on Japanese defenders on Pacific Islands showed that under the right conditions, a defender could exact a terrible price from assaulting forces, significantly depleting and delaying enemy forces until reinforcements could be deployed to appropriate places via the sea, and inland.

In the event of invasion, the Royal Navy would have sailed to the landing places, possibly taking several days. It is now known that the Germans planned to land on the southern coast of England; one reason for this site was that the narrow seas of the English Channel could be blocked with mines, U-boats and torpedo boats. While German naval forces and the Luftwaffe could have extracted a high price from the Royal Navy, they could not have hoped to prevent interference with attempts to land a second wave of troops and supplies that would have been essential to German success—even if, by then, the Germans had captured a port essential for bringing in significant heavy equipment. In this scenario, British land forces would have faced the Germans on more equal terms than otherwise and it was only necessary to delay the German advance, preventing a collapse until the German land forces were, at least temporarily, isolated by the Royal Navy and then mounting a counter attack. [James, 2006, pp38–40.]

Scholarly consideration of the likely outcome of invasion, including war games at Royal Military Academy Sandhurst in 1974, [cite web | title=Operation Sealion - summary of an exercise held at the Staff College | work=Sandhurst in 1974 | url=http://homepage.mac.com/a.biermann/Sealion/Personal7.html|accessdate=2006-06-01] agrees that while German forces would have been able to land and gain a significant beachhead, intervention of the Royal Navy would have been decisive and, even with the most optimistic assumptions, the German army would not have penetrated further than GHQ Line and would have been defeated. [cite web | title=Why Sealion is not an option for Hitler to win the war | work=essay | url=http://www.flin.demon.co.uk/althist/seal1.htm | accessdate=2006-06-01] [cite web | title=Why Operation Sealion Wouldn't Work | work=essay | url=http://gateway.alternatehistory.com/essays/Sealion.html | accessdate=2006-06-01] [cite web | title=Sea Lion vs. Overlord | work= | url=http://www.militaryhistoryonline.com/wwii/articles/sealionvsoverlord.aspx | accessdate=2006-06-01] [Evans, 2004, the outcome is a major theme of this work, Evans gives emphasis to German logistical problems.]

Following the failure to gain even local air superiority in the Battle of Britain, Operation Sealion was postponed indefinitely. Hitler and his generals were aware of the problems of an invasion. Hitler was not ideologically committed to a long war with Britain and many commentators suggest that German invasion plans were a feint never to be put into action. [Liddell Hart, 1958, pp126–127.]

While Britain may have been militarily secure in 1940, both sides were aware of the possibility of a political collapse. If the Germans had won the Battle of Britain, the Luftwaffe would have been able to strike anywhere in southern England and with the prospect of an invasion, the British government would have come under pressure to come to terms: the extensive anti-invasion preparations demonstrated to Germany and to the people of Britain that whatever happened in the air, the United Kingdom was both able and willing to defend itself. [MacKenzie, 1995, p180–184.]

ee also

*Eastbourne Redoubt home of the Combined Service Museum
*Dymchurch Redoubt

References

Notes

General references

*cite book
last = Alanbrooke
first = Field Marshal Lord
authorlink = Alan Brooke, 1st Viscount Alanbrooke
title = War Diaries 1939–1945
publisher = Phoenix Press
series =
year = 2001
isbn = 1-84212-526-5
*cite book
last = Banks
first = Sir Donald
title = Flame Over Britain
publisher = Sampson Low, Marston and Co
series =
year = 1946
isbn =
*cite book
last = Cameron
first = A Bryce
title = Under Sand, Ice & Sea
publisher = Trafford Publishing
year = 2000
isbn = 1-55212-319-7
*cite book
last = Churchill
first = Winston
authorlink = Winston Churchill
title = Their Finest Hour
publisher = Penguin
series = The Second World War, Volume II
origdate = 1949
year = 2005
isbn = 0-141-44173-9
*cite book
last = Cox
first = Richard
title = Operation Sea Lion
publisher = Thornton Cox
year = 1975
isbn = 0-902726-17-X
*cite book
last = Cruickshank
first = Dan
authorlink = Dan Cruickshank
title = Invasion — Defending Britain from Attack
publisher = Boxtree
year = 2001
isbn = 0-7522-2029-2
*cite book
last = Evans
first = Martin Marix
title = Invasion! Operation Sealion 1940
publisher = Longman
year = 2004
isbn = 0-582-77294-X
*cite book
last = Fleming
first = Peter
title = Invasion 1940
publisher = Rupert Hart-Davis
year = 1957
*cite book
last = Foot
first = William
title = Beaches, fields, streets, and hills ... the anti-invasion landscapes of England, 1940
publisher = Council for British Archaeology
year = 2006
isbn = 1-902771-53-2
*cite book
last = Gillies
first = Midge
authorlink = Midge Gillies
title = Waiting for Hitler — Voices from Britain on the Brink of Invasion
publisher = Hodder & Stoughton
year = 2006
isbn = 0-340-83798-5
*cite book
last = Hayward
first = James
authorlink = James Hayward
title = The Bodies On The Beach — Sealion, Shingle Street and the Burning Sea Myth of 1940
publisher = CD41 Publishing
series =
year = 2001
isbn = 0-9540549-0-3
*cite journal
quotes= no
last= James
first= Brian
year= 2006
month= September
title= Pie in the Sky
journal= History Today
*cite book
last = Lampe
first = David
title = The Last Ditch: Britain's Resistance Plans Against the Nazis
publisher = Greenhill Books
foreword by = Gary Sheffield
year = 2007
*cite book
last = Liddell Hart
first = Basil
authorlink = Basil Liddell Hart
title = The German Generals Talk
publisher = Berkley Publishing
origdate = 1948
year = 1958
*cite book
last = Longmate
first = Norman
authorlink = Norman Longmate
title = If Britain Had Fallen
publisher = Greenhill Books
origdate = 1972
year = 2004
isbn = 978-1853675997
*cite book
last = Lowry
first = Bernard
title = British Home Defences 1940–45
publisher = Osprey Publishing
series =
year = 2004
isbn = 1-84176-767-0
*cite book
last = Mace
first = Martin
title = Vehicles of the Home Guard
publisher = Historic Military Press
year = 2001
month = July
isbn = 1-901313-08-5
*cite book
last = MacKenzie
first = S. P.
title = The Home Guard — A Military and Political History
publisher = Oxford University Press
year = 1995
isbn = 0-19-820577-5
*cite book
last = Macksey
first = Kenneth
authorlink = Kenneth Macksey
title = Invasion: Alternative History of the German Invasion of England, July 1940
publisher = Greenhill Books
origyear = 1980
year = 1999
isbn = 978-1853673610
*cite book
last = Osborne
first = Mike
title = Defending Britain ... twentieth century military structures in the landscape
publisher = Tempus Publishing
year = 2004
isbn = 0-7524-3134-X
*cite book
last = Ruddy
first = Austin
title = British Anti-Invasion Defences 1940–1945
publisher = Historic Military Press
year = 2003
isbn = 1-901313-20-4
*cite book
last = Ward
first = Arthur
title = Resisting the Nazi Invader
publisher = Constable and Co
year = 1997
isbn = 0-09-476750-5
*cite book
last = White
first = John Baker
title = The Big Lie
publisher = Evans Brothers
year = 1955
*cite book
last = Wills
first = Henry
authorlink = Henry Wills
title = Pillboxes: A Study of UK Defences
publisher = Leo Cooper
year = 1985
isbn = 0-436-57360-1

Official documents

*"Consolidated Instructions to Invasion Committees in England and Wales" (July 1942) HM Government.
*cite book
last =
first =
title = Barrel Flame Traps, Flame Warfare
publisher = War Office
series = Military Training Pamphlet No. 53. Part 1
month = July | year = 1942
isbn =

Collections

*cite web
url = http://www.nationalarchives.gov.uk
title = The National Archives
accessdate = 2007-02-19
work = Repository of UK government records
*cite web
url = http://www.bbc.co.uk/ww2peopleswar/
title = WW2 People's War
accessdate = 2007-02-19
work =
publisher = BBC - '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 bbc.co.uk/ww2peopleswar'

Further reading

*"William Foot" - "The Battlefields That Nearly Were. Defended England 1940" (Stroud: Tempus Publishing 2006) ISBN 9780752438498
*"Mike Osborne" - "20th Century Defences in Britain" (Stroud: Tempus Publishing 2003) ISBN 0-9540378-1-2
*"C Bird " -"Silent Sentinels - A study of the fixed defences constructed in Norfolk during WWI and WWII" (Dereham: The Larks Press 1999) ISBN 0-948400-81-1
*"Stewart Ross" - "World War II Britain. History from Buildings" (London: Franklin Watts 2006) ISBN 0-7496-6468-1

External links

* [http://www.bbc.co.uk/history/worldwars/wwtwo/invasion_ww2_01.shtml The German Threat to Britain in World War Two.] By Dan Cruickshank. BBC website.
* [http://www.diverse.tv/programme.aspx?id=110 The Real Dad's Army] - TV Documentary.
* [http://news.bbc.co.uk/1/hi/england/kent/4982116.stm Churchill's mysterious map.]
* [http://www.pillboxesuk.co.uk/html/defence_types.html Pillboxesuk.co.uk.]
* [http://ads.ahds.ac.uk/catalogue/specColl/dob/index.cfm Defence of Britain database.]