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80-709: Today Moyecques is best known as the site of the Fortress of Mimoyecques , the modern name for an underground base built by Nazi Germany during the Second World War to house the V-3 cannon that was intended to bombard London . 50°50′53″N 1°46′05″E  /  50.848°N 1.768°E  / 50.848; 1.768 This Pas-de-Calais geographical article is a stub . You can help Misplaced Pages by expanding it . Fortress of Mimoyecques The Fortress of Mimoyecques ( French pronunciation: [mimɔjɛk] )

160-536: A 97-kilogram (214 lb) finned shell (known as the Sprenggranate 4481 ) would be accelerated by numerous small low-pressure detonations from charges in branches off the barrel, each fired electrically in sequence. Each barrel would be 15 cm (5.9 in) in diameter. The gun was still in its prototype stages, but Hitler was an enthusiastic supporter of the idea and ordered that maximum support be given to its development and deployment. In August 1943 he approved

240-562: A German technician who could be interrogated for information. The suggestion was approved, but was never put into effect. In the end the Chiefs of Staff instructed General Eisenhower to begin intensive attacks on the so-called "Heavy Crossbow" sites, including Mimoyecques, which was still believed to be intended for use as a rocket-launching site. The Allied air forces carried out several bombing raids on Mimoyecques between November 1943 and June 1944 but caused little damage. The bombing disrupted

320-434: A few inches off would cause a great variance in the velocity, and with it, the range. Then, with the variance determined, the additional quantity of propellant was calculated, and its measure taken from a special car and added to the regular charge. After 65 rounds had been fired, each of progressively larger caliber to allow for wear, the barrel was sent back to Krupp and rebored with a new set of shells. The shell's explosive

400-400: A high velocity that each successive shot wore away a considerable amount of steel from the rifled bore. Each shell was sequentially numbered according to its increasing diameter, and had to be fired in numeric order, lest the projectile lodge in the bore and the gun explode. Also, when the shell was rammed into the gun, the chamber was precisely measured to determine the difference in its length:

480-463: A longer range, and with a substantially higher rate of fire. The unfinished Iraqi super gun would also have been substantially bigger. The Paris Gun shells weighed 106 kg (234 lb). The shells initially used had a diameter of 216 mm (8.5 in) and a length of 960 mm (38 in). The main body of the shell was composed of thick steel, containing 7 kg (15 lb) of TNT . The small amount of explosive—around 6.6% of

560-479: A man-made object, so high that gunners, in calculating where the shells would land, had to take into account the rotation of the Earth. For the first time in warfare, deadly projectiles rained down on civilians from the stratosphere". This reduced drag from air resistance, allowing the shell to achieve a range of over 130 kilometres (81 mi). The unfinished V-3 cannon would have been able to fire larger projectiles to

640-533: A minute – 600 rounds every hour – into the British capital, which Winston Churchill later commented would have constituted "the most devastating attack of all". The Allies knew nothing about the V-3 but identified the site as a possible launching base for V-2 ballistic missiles, based on reconnaissance photographs and fragmentary intelligence from French sources. Mimoyecques was targeted for intensive bombardment by

720-503: A mushroom farm. 30 metres (98 ft) of the southern tunnel had to be removed to clear the blockage; the entrance now visible is not the original one built by the Germans. The southern entrance had been bricked up again by the 1970s. Moved to discover this forgotten construction, Vasseur, helped by family and friends, cleared the tunnels and installed an electricity supply. The société à responsabilité limitée "La Forteresse de Mimoyecques"

800-471: A new long-range gun, although there was initial press speculation on the origin of the shells. This included the theory they were being fired by German agents close by Paris, or even within the city itself, so abandoned quarries close to the city were searched for a hidden gun. Another possibility was that German forces had penetrated the front line, but authorities realized that such heavy artillery could not be moved and emplaced so quickly. The press reported

880-677: A replacement for the Paris Gun—which was specifically banned under the Versailles Treaty . This work eventually led to the V-2 rocket that was used in World War II . Despite the ban, Krupp continued theoretical work on long-range guns. They started experimental work after the Nazi government began funding the project upon coming to power in 1933. This research led to the 21 cm K 12 (E) , a refinement of

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960-441: A second passageway, designated Gallery No. 1, running parallel to the main tunnel at a distance of 24.5 metres (80 ft). Further workings existed at depths of 62 m (203 ft), 47 m (154 ft) and 30 m (98 ft), each serving different purposes associated with the drifts and the guns. The 62 m workings were constructed to facilitate the removal of spoil from the drifts, while those at 47 m were connected with

1040-462: A stacked cluster of five HDP gun tubes, for a total of 25 guns. The smoothbore design of the HDP would enable a much higher rate of fire than was possible with conventional guns. The entire battery would be able to fire up to 10 shots a minute, capable in theory of hitting London with 600 projectiles every hour. Both facilities were to be served by an underground railway tunnel of standard gauge, connected to

1120-424: A streamlined, lightweight, ballistic cap and the side had grooves that engaged with the rifling of the gun barrel, spinning the shell as it was fired so its flight was stable. Two copper driving bands provided a gas-tight seal against the gun barrel during firing. The Paris gun was used to shell Paris at a range of 120 km (75 mi). The gun was fired from a wooded hill (Le mont de Joie) near Crépy , and

1200-528: A turntable. The original breech of the old 38 cm (15 in) gun did not require modification or reinforcement. Since it was based on a naval weapon, the gun was manned by a crew of 80 Imperial Navy sailors under the command of Vice-Admiral Maximilian Rogge, chief of the Ordnance branch of the Admiralty. It was surrounded by several batteries of standard army artillery to create a "noise-screen" chorus around

1280-509: A vast underground museum complex. In May 1943 Albert Speer , the Reich's Minister of Armaments and War Production, informed Adolf Hitler of work that was being carried out to produce a large-calibre gun capable of firing hundreds of shells an hour over long distances. The newly designed gun, codenamed the Hochdruckpumpe ("High Pressure Pump", HDP for short) and later designated as the V-3 ,

1360-411: Is the modern name for a Second World War underground military complex built by the forces of Nazi Germany between 1943 and 1944. It was intended to house a battery of fixed V-3 cannons permanently aimed at London, 165 kilometres (103 mi) away. Originally codenamed Wiese ("Meadow") or Bauvorhaben 711 ("Construction Project 711"), it is located in the commune of Landrethun-le-Nord in

1440-584: The Pas-de-Calais region of northern France, near the hamlet of Mimoyecques about 20 kilometres (12 mi) from Boulogne-sur-Mer . It was constructed by a mostly German workforce recruited from major engineering and mining concerns, augmented by prisoner-of-war slave labour. The complex consists of a network of tunnels dug under a chalk hill, linked to five inclined shafts in which 25 V-3 guns would have been installed, all aimed at London . The guns would have been able to fire ten dart-like explosive projectiles

1520-465: The Ruhr and Soviet prisoners of war who were used as slave labourers. The intensive Allied bombing campaign caused delays, but construction work continued nonetheless at a high pace underground. The original plans had envisaged having the first battery of five guns ready by March 1944 and the full complement of 25 guns by 1 October 1944, but these target dates were not met. In 1943 French agents reported that

1600-502: The Allied air forces from late 1943 onwards. Construction work was seriously disrupted, forcing the Germans to abandon work on part of the complex. The rest was partly destroyed on 6 July 1944 by No. 617 Squadron RAF , who used ground-penetrating 5,400-kilogram (12,000 lb) " Tallboy " earthquake bombs to collapse tunnels and shafts. This also entombed hundreds of slave workers underground. Though attempts were made to continue construction,

1680-519: The Allies as the "Heavy Crossbow" sites. Sanders' report was submitted to the War Cabinet on 19 March 1945. Even at this stage the true purpose of the site was unclear. Claims that it had been intended to be used for "electro-magnetic projectors" ( railguns ), firing huge shells at London, were debunked by Lord Cherwell , Winston Churchill 's scientific adviser, who calculated that it would take sixty times

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1760-469: The Calais–Boulogne main line, and underground ammunition storage galleries which were tunneled at a depth of about 33 m (108 ft). The western site was abandoned at an early stage after being disrupted by Allied bombing, and only the eastern complex was built. The drifts were angled at 50 degrees, reaching a depth of 105 m (344 ft). Owing to technical problems with the gun prototype,

1840-612: The German howitzer used against Belgian forts in the Battle of Liège in 1914; indeed, the French called them by this name as well. They were also confused with the smaller " Langer Max " (Long Max) cannon, from which they were derived. Although the famous Krupp -family artillery makers produced all these guns, the resemblance ended there. As military weapons, the Paris Guns were not a great success:

1920-572: The German bombardment. Between 320 and 367 shells were fired, at a maximum rate of around 20 per day. The shells killed 250 people and wounded 620, and caused considerable damage to property. The worst incident was on 29 March 1918, when a shell hit the roof of the St-Gervais-et-St-Protais Church , collapsing the roof onto the congregation then hearing the Good Friday service. A total of 91 people were killed and 68 were wounded. There

2000-409: The German gun's range as about 62 miles (100 km), which amazed American ordnance officers, and the shells as 240 millimetres (9.4 in), compared to the 17 inches (430 mm) caliber of heavy German siege shells. The previous world distance record was German bombardment of Dunkirk from 22 miles (35 km), while the best American gun had a range of 19 miles (31 km). Experts thought that

2080-472: The German weapon might be a product of the Škoda Works . Three emplacements for the gun were located within days by the French reconnaissance pilot Didier Daurat , the path of the shells which landed in Paris having revealed the direction from which they were being fired. The closest emplacement was engaged by a 34 cm railway gun while the other two sites were bombed by aircraft, although this failed to interrupt

2160-413: The Germans found that a design fault caused the projectiles to begin "tumbling" in flight at speeds above 1,000 m/s (3,300 ft/s), causing them to fall well short of the target. This was not discovered until over 20,000 projectiles had already been manufactured. After the devastating raid of 6 July, the Germans held a high-level meeting on the site's future at which Hitler ordered major changes to

2240-523: The Germans soon halted work at Mimoyecques entirely as the Allies advanced up the coast following the Normandy landings . It fell to the Canadian 3rd Infantry Division on 5 September 1944 without resistance, a few days after the Germans withdrew from the area. The complex was partly demolished just after the war on Churchill's direct orders (and to the great annoyance of the French, who were not consulted), as it

2320-607: The Germans were planning to mount an offensive against the United Kingdom that would involve the use of secret weapons resembling giant mortars sunk in the ground and served by rail links. The first signs of abnormal activity at Mimoyecques were spotted by analysts at the Allied Central Interpretation Unit in September 1943, when aerial reconnaissance revealed that the Germans were building railway loops leading to

2400-610: The Germans. One spare mounting was captured by American troops in Bruyères-sur-Fère, near Château-Thierry , but the gun was never found; the construction plans seem to have been destroyed as well. Under the terms of the Treaty of Versailles , the Germans were required to turn over a complete Paris Gun to the Allies, but they never complied with this. In the 1930s, the German Army became interested in rockets for long-range artillery as

2480-552: The HDP gun. The tunnels also house memorials to Joseph Kennedy, the other bomber crew members killed during raids on the site, and the forced labourers who lost their lives during construction. In 2011, the museum had about 11,000 visitors, of whom 53% were French, 18% Belgian and 16% British. Paris gun The Paris Gun ( German : Paris-Geschütz / Pariser Kanone ) was a type of German long-range siege gun , several of which were used to bombard Paris during World War I . They were in service from March to August 1918. When

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2560-682: The Nord-Pas-de-Calais regional council, the European Union and a private benefactor. The Conservatory's interest was due to the presence on the site of a large bat colony that included rare species, such as the Greater Horseshoe Bat , Geoffroy's Bat and the Pond Bat . The intercommunality of the Terre des Deux Caps and the authorities in nearby Landrethun set up a partnership to operate

2640-691: The Paris Gun design concept. Although it was broadly similar in size and range to its predecessor, Krupp's engineers had significantly reduced the problem of barrel wear. They also improved mobility over the fixed Paris Gun by making the K 12 a railway gun . The first K 12 was delivered to the German Army in 1939 and a second in 1940. During World War II, they were deployed in the Nord-Pas-de-Calais region of France; they were used to shell Kent in Southern England between late 1940 and early 1941. One gun

2720-455: The Paris Gun, was found by advancing US troops at the beginning of August, on the north side of the wooded hill at Coucy-le-Château-Auffrique , some 86 kilometres (53 mi) from Paris. The gun was taken back to Germany in August 1918 as Allied advances threatened its security. No guns were ever captured by the Allies. It is believed that near the end of the war they were completely destroyed by

2800-476: The V-1 and V-2 projects – the V-3 had not been uncovered by Allied intelligence before the war's end. The British scientist and military intelligence expert Reginald Victor Jones later commented that "[intelligence] techniques that had been used against the flying bomb and the rocket appeared to have failed against HDP [V-3], and there had to be a reason. Basically, it was that with our limited effort we had to concentrate on

2880-590: The V-weapons. On 21 March 1944 the British Chiefs of Staff discussed the shortage of intelligence but were told by Reginald Victor Jones , one of the "Crossbow Committee" members, that little information was leaking out because the workforce was predominantly German. The committee's head, Duncan Sandys , pressed for greater efforts and proposed that the Special Operations Executive be tasked to kidnap

2960-530: The attention of Churchill and advised: "Since this installation constitutes a potential threat to London, it would be wise to ensure that it is demolished whilst our forces are still in France." Churchill later commented that the V-3 installation at Mimoyecques "might well have launched the most devastating attack of all on London." The discovery of the site's true purpose produced some recriminations in London, as – unlike

3040-428: The big gun so that it could not be located by French and British spotters. The projectile flew significantly higher than projectiles from previous guns. Writer and journalist Adam Hochschild put it this way: "It took about three minutes for each giant shell to cover the distance to the city, climbing to an altitude of 40 km (25 mi) at the top of its trajectory. This was by far the highest point ever reached by

3120-438: The caliber from 380 mm (15 in) to 210 mm (8 in). The tube was 31 metres (102 ft) long and projected 13.9 m (46 ft) out of the end of the gun, so an extension was bolted to the old gun-muzzle to cover and reinforce the lining tube. A further, 6 m (20 ft) long smooth-bore extension was attached to the end of this, giving a total barrel length of 37 m (121 ft). This smooth section

3200-442: The capital were suspended due to demand. The initial assumption was these were bombs dropped from an airplane or Zeppelin flying too high to be seen or heard, or perhaps an " aerial torpedo ". Within a few hours, sufficient casing fragments had been collected to show that the explosions were the result of shells, not bombs. By the end of the day, military authorities were aware the shells were being fired from behind German lines by

3280-407: The chalk layer extends several hundred metres below the surface, providing a deep but easily tunnelled rock layer. The chalk is easy to excavate and strong enough to dig tunnels without using timber supports. Although the site's road links were poor, it was only a few kilometres west of the main railway line between Calais and Boulogne-sur-Mer . The area was already heavily militarised; as well as

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3360-401: The completion of the actual battery. To reach England, the weapon needed barrels 127 metres (417 ft) long, so it could not be moved; it would have to be deployed from a fixed site. A study carried out in early 1943 had shown that the optimal location for its deployment would be within a hill with a rock core into which inclined drifts could be tunneled to support the barrels. The site

3440-521: The construction of a battery of HDP guns in France to supplement the planned V-1 and V-2 missile campaigns against London and the south-east of England. Speer noted afterwards: On my suggestion, the Führer has decided that the risk must be stood to award contracts at once for the "high-pressure pump," without waiting for the results of firing trials. Maximum support is to be accorded to the experimental ranges at Hillersleben and Misdroy , and especially to

3520-493: The construction project and the initial raids of 5 and 8 November 1943 caused work to be delayed for about a month. The Germans subsequently decided to abandon the western site, where work had not progressed very far, and concentrated on the eastern site. On 6 July 1944 the Royal Air Force began bombing the site with ground-penetrating Tallboy "earthquake" bombs . One Tallboy hit the concrete slab on top of Drift IV, collapsing

3600-437: The drift. Three others penetrated the tunnels below and substantially damaged the facility, causing several of the galleries to collapse in places. Around 300 Germans and forced labourers were buried alive by the collapses. Adding to the Germans' difficulties, major technical problems were discovered with the HDP gun projectiles. They had been designed to exit the barrels at a speed of about 1,500 m/s (4,900 ft/s), but

3680-601: The explosion of the launching charge." The Allies were unaware of the HDP gun and therefore of the Mimoyecques site's true purpose. Allied intelligence believed at the time that the V-2 rocket had to be launched from tubes or "projectors", so it was assumed that the inclined shafts at Mimoyecques were intended to house such devices. The lack of intelligence on Mimoyecques was frustrating for those involved in Crossbow operations to counter

3760-594: The first shell landed at 7:18 a.m. on 23 March 1918 on the Quai de la Seine , the explosion being heard across the city. Shells continued to land at 15-minute intervals, with 21 counted on the first day. On the first day, fifteen people were killed and thirty-six wounded. The effect on morale in Paris was immediate: by 27 March, queues of thousands had started at the Gare d'Orsay and, at the Gare Montparnasse, ticket sales out of

3840-660: The fortifications of the Atlantic Wall on the cliffs of Cap Gris Nez to the northwest, there was a firing base for at least one conventional Krupp K5 railway gun about 5 kilometres (3.1 mi) to the south in the nearby quarries of Hidrequent-Rinxent . Construction began in September 1943 with the building of railway lines to support the work, and excavation of the gun shafts began in October. The initial layout comprised two parallel complexes approximately 1,000 metres (3,300 ft) apart, each with five drifts which were to hold

3920-443: The garrison. Trains would have entered the facility and unloaded shells and propellant for the guns. Galleries 6–10, the central group, gave access to the guns, while galleries 3–5 and 11–13 were intended for use as access tunnels and perhaps also storage areas. They were all connected by Gallery No. 2, which ran parallel to the main railway tunnel at a distance of 100 metres (330 ft). Galleries 6–10 were additionally connected by

4000-441: The gradual acceleration of the shell by a series of small charges spread over the length of the barrel might be the solution to the problem of designing very long-range guns. Coenders proposed the use of electrically activated charges to eliminate the problem of the premature ignition of the subsidiary charges experienced by previous multi-chamber guns. The HDP would have a smooth barrel over 100 metres (330 ft) long, along which

4080-434: The guns were first employed, Parisians believed they had been bombed by a high-altitude Zeppelin , as the sound of neither an airplane nor a gun could be heard. They were the largest pieces of artillery used during the war by barrel length, and qualify under the (later) formal definition of large-calibre artillery . Also called the " Kaiser Wilhelm Geschütz " (" Kaiser Wilhelm Gun"), they were often confused with Big Bertha ,

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4160-530: The handling of exhaust gases from the guns and those at 30 m gave access to the breeches of the guns. The lower levels of the workings were accessed via lift shafts, and mining cages were used during construction. The construction work was carried out by over 5,000 workers, mostly German engineers drafted in from several companies including Mannesmann , Gute Hoffnungshütte , Krupp and the Vereinigte Stahlwerke , supplemented by 430 miners recruited from

4240-463: The most urgent problem, and thus on catching weapons not so much at the research stage (although we sometimes achieved this) as in the development stage – which usually meant when trials were showing promise." He concluded at the time, in April 1945, that the intelligence failure had not made much practical difference given the fact that the Germans had failed to develop the HDP into an effective weapon: "there

4320-527: The north and south entrances to the railway tunnel into the site. A subsequent investigation by the British Bombing Research Mission concluded that the entrances had been heavily blocked and that it would be a very difficult and lengthy engineering task to reinstate them. The British action was taken without informing the French beforehand and infuriated Charles de Gaulle , who considered it a violation of France's national sovereignty. After

4400-410: The output of Battersea Power Station to fire a one-ton shell. Sanders' investigation brought to light the V-3 project for the first time, to the alarm of the British government. He concluded that although the site had been damaged it "could be completed or adapted for offensive action against this country at some future date, and [its] destruction is a matter of importance." Sandys brought the matter to

4480-494: The payload was small, the barrel required frequent replacement, and the guns' accuracy was good enough for only city-sized targets. The German objective was to build a psychological weapon to attack the morale of the Parisians, not to destroy the city itself. Due to the weapon's apparent total destruction by the Germans in the face of the final Entente offensives, its capabilities are not known with full certainty. Figures stated for

4560-406: The quarries until 2010, when the surviving plates were returned to Mimoyecques, where they are now on display. Despite the closure of the railway tunnel entrances it was still possible for many years to get into the complex by climbing down one of the inclined drifts. In 1969, Marie-Madeleine Vasseur, a farmer from Landrethun, had the southern entrance excavated so that the tunnels could be used as

4640-482: The scope of the project was reduced; drifts I and II were abandoned at an early date and only III, IV and V were taken forward. They came to the surface at a concrete slab or Platte 30 m (98 ft) wide and 5.5 m (18 ft) thick, in which there were narrow openings to allow the projectiles to pass through. The openings in the slab were protected by large steel plates, and the railway tunnel entrances were further protected by armoured steel doors. Each drift

4720-412: The second such attack, on 12 August, Lt Joseph P. Kennedy, Jr.  – the elder brother of future US President John F. Kennedy  – was killed when the drone aircraft exploded prematurely. By the end of the bombing campaign, over 4,100 tons of bombs had been dropped on Mimoyecques, more than on any other V-weapons site. The Mimoyecques site was never formally abandoned, but German forces left it at

4800-408: The site under the management of the existing museum of La Coupole near Saint-Omer. The director of the latter, historian Yves le Maner, designed the contents of a new museum that was constructed at a cost of €360,000. The site reopened to the public on 1 July 2010. As well as presenting a history of the V-weapons and of the site, the museum enables visitors to see some of the tunnels and a mock-up of

4880-400: The site was unclear, but it was thought to be some kind of shelter for launching rockets or flying bombs. An MI6 agent reported that "a concrete chamber was to be built near one of the tunnels for the installation of a tube, 40 to 50 metres long, which he referred to as a 'rocket launching cannon ' ". The shafts were interpreted as "air holes to allow for the expansion of the gases released by

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4960-427: The site's development. On 12 July 1944 he signed an order instructing that only five HDP guns were to be installed in a single drift. The two other drifts were to be reused to house a pair of Krupp K5 artillery pieces, reamed out to a smooth bore with a diameter of 310 millimetres (12 in), which were to use a new type of long-range rocket-propelled shell. A pair of Rheinbote missile launchers were to be installed at

5040-537: The start of September 1944 as the Allies advanced northeast from Normandy towards the Pas de Calais. It was captured on 5 September by the Canadian 3rd Infantry Division. In September 1944, Duncan Sandys ordered the constitution of a Technical Inter-Services Mission under Colonel T.R.B. Sanders . It was given the task of investigating the V-weapons sites at Mimoyecques, Siracourt , Watten , and Wizernes , collectively known to

5120-596: The tunnel entrances. These plans were soon abandoned as Allied ground forces advanced towards Mimoyecques, and on 30 July the Organisation Todt engineers were ordered to end construction work. The Allies were unaware of this and mounted further attacks on the site as part of the United States Army Air Forces experimental Operation Aphrodite , involving radio-controlled B-24 Liberators packed with explosives. Two such attacks were mounted but failed; in

5200-419: The tunnels into the eastern and western sites. Further reconnaissance flights in October 1943 photographed large-scale activity around the tunnels. An analyst named André Kenny discovered a series of shafts when he saw from a reconnaissance photograph that a haystack concealing one of them had disintegrated, perhaps through the effects of a gale, revealing the entrance, a windlass and pulley . The purpose of

5280-468: The war, the Mimoyecques site lay abandoned. Much of the equipment left by the Germans was disposed of as scrap metal. A complete set of four steel plates, weighing 60 tons, that were intended to protect the entrances to the drifts were bought by the manager of the Hidrequent-Rixent quarries to be cut up for use in rock-crushing machinery. Rediscovered by local historians in the 1990s, they remained at

5360-543: The weapon's size, range, and performance varied widely depending on the source—not even the number of shells fired is certain. In the 1980s, a long note on the gun was discovered and published. This was written by Dr. Fritz Rausenberger (in German), the Krupp engineer in charge of the gun's development, shortly before his death in 1926. Thanks to this, the details of the gun's design and capabilities were considerably clarified. The gun

5440-563: The weight of the shell—meant that the effect of its shellburst was small for the shell's size. The thickness of the shell casing, to withstand the forces of firing, meant that shells would explode into a comparatively small number of large fragments, limiting their destructive effect. A crater produced by a shell falling in the Tuileries Garden was described by an eyewitness as being 10 to 12 ft (3.0 to 3.7 m) across and 4 ft (1.2 m) deep. The shells were propelled at such

5520-453: Was an unloading platform which gave access to ten cross galleries (numbered 3–13 by the Germans), driven at right angles to the main tunnel at intervals of 24 metres (79 ft). Each gallery was fitted with a 600 mm ( 1 ft  11 + 5 ⁄ 8  in ) gauge railway track. On the east side of the tunnel were chambers intended to be used as store rooms, offices and quarters for

5600-451: Was capable of firing a 106-kilogram (234 lb) shell to a range of 130 kilometres (81 mi) and a maximum altitude of 42.3 km (26.3 mi) —the greatest height reached by a human-made projectile until the first successful V-2 flight test in October 1942. At the start of its 182-second flight, each shell from the Paris Gun reached a speed of 1,640 m/s (5,904 km/h; 5,381 ft/s; 3,669 mph). The distance

5680-486: Was constituted in 1984 to operate the site as a museum under the name of Forteresse de Mimoyecques – Un Mémorial International . The museum closed at the end of the 2008 season when the owner retired. Subsequently, the nonprofit organisation Conservatoire d'espaces naturels du Nord et Pas-de-Calais (Conservatory of natural sites of the Nord and Pas-de-Calais) purchased it at a cost of € 330,000, with funding provided by

5760-408: Was contained in two compartments, separated by a wall. This strengthened the shell and supported the explosive charge under the acceleration of firing. One of the shell's two fuzes was mounted in the wall, with the other in the base of the shell. The fuzes proved very reliable as every single one of the 303 shells that landed in and around Paris successfully detonated. The shell's nose was fitted with

5840-615: Was identified by a fortification expert, Major Bock of the Festungs-Pionier-Stab 27 of the Fifteenth Army LVII Corps based in the Dieppe area. A limestone hill near the hamlet of Mimoyecques , 158 metres (518 ft) high and 165 kilometres (103 mi) from London, was chosen to house the gun. It had been selected with care; the hill in which the facility was built is primarily chalk with very little topsoil cover, and

5920-414: Was intended to improve accuracy and reduce the dispersion of the shells, as it reduced the slight yaw a shell might have immediately after leaving the gun barrel produced by the gun's rifling . The barrel was braced to counteract barrel drop due to its length and weight, and vibrations while firing; it was mounted on a special rail-transportable carriage and fired from a prepared, concrete emplacement with

6000-468: Was little warning; [but] there was little danger." Following the recommendation that the site should be destroyed, the Royal Engineers stacked ten tons of British 500 lb (230 kg) bombs and captured German plastic explosive in the tunnels at Mimoyecques and detonated them on 9 May. This failed to achieve the desired effect, and on 14 May, a further 25 tons of explosives were used to bring down

6080-442: Was no firing between 25 and 29 March, when the first barrel was being replaced; an unconfirmed intelligence report claimed that it had exploded. Barrels were probably changed again between 7–11 April and again between 21–24 April. The diameter of the later shells increased from 21 to 24 cm (8.3 to 9.4 in), indicating that the used barrels had been re-bored. A further emplacement, later identified as specifically designed for

6160-562: Was one of the V-weapons  – Vergeltungswaffen ("retaliation or vengeance weapons") – developed by Nazi Germany in the later stages of the war to attack Allied targets. Long-range guns were not a new development, but the high-pressure detonations used to fire shells from previous such weapons, including the Paris gun , rapidly wore out their barrels. In 1942, August Coenders , inspired by previous designs of multi-chamber guns, suggested that

6240-441: Was oriented on a bearing of 299°, to the nearest degree – a direct line on Westminster Bridge . Although the elevation and direction of the guns could not be changed, it would have been possible to alter the range by varying the amount of propellant used in each shot. This would have brought much of London within range. The railway tunnel ran in a straight line for a distance of about 630 m (2,070 ft) . Along its west side

6320-525: Was so far that the Coriolis effect —the rotation of the Earth—was substantial enough to affect trajectory calculations. The gun was fired at an azimuth of 232 degrees (southwest) from Crépy-en-Laon , which was at a latitude of 49.5 degrees north. Seven barrels were constructed. They used worn-out 38 cm SK L/45 "Max" 17,130 mm (674 in) long gun barrels that were fitted with an internal tube that reduced

6400-450: Was still seen as a threat to the United Kingdom. It was later reopened by private owners, first in 1969 to serve as a mushroom farm and subsequently as a museum in 1984. A nature conservation organisation acquired the Fortress of Mimoyecques in 2010, and La Coupole , a museum near Saint-Omer housing a former V-2 rocket base, took over its management. It continues to be open to the public as

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