Text & Pictures: Serge van Oosterzee (other as mentioned) © sbap 2014


The blockhaus of Éperlecques (also known as the "bunker of Watten") is a second world war bunker located in the woods of Éperlecques, property of the town in the Pas-de-Calais department in Northern France. Codenamed Kraftwerk Nord West, it was build by Nazi Germany from 1943 to 1944 to become a launch base for the V2 missiles targeting London and Southern England. Build to accommodate more than 100 missiles at once and to launch about 36 of them per day, the blockhaus is also supposed to have been composed of a liquid oxygen factory and a railway station, protected against bombs, allowing the site to be supplied with rockets and materials from the production factories in Germany. It was build by forced labourers from concentration- and other work camps and by force enlisted Frenchmen.

The blockhaus was never finished due to the repetitive bombing by the British and Americans within the operation Crossbow. These attacks caused important damages and prevented the site to be used in its initial role. Captured by the allies at the beginning of September 1944, its role was only discovered after the end of the war. Since 1986 the bunker of Watten is on the inventory list of historical monuments.


Aerial view of the Eperlecques wood and the blockhaus site (Google Earth)


In December 1942, Albert Speer ordered the officers and engineers of Peenemünde (of which Colonel Gerhard Stegmair, Ernst Steinhoff and Lieutenant-Colonel Georg Thom) to go to Artois in Northern France to find a suitable launch site for A4 missiles. This site was found west of the little town of Watten in the woods of Éperlecques in the Pas-de-Calais department and was codenamed 'Kraftwerk Nord West' (North West Generating Station). Nowadays it is called 'bunker of Watten' or just 'Watten'.
The assets of the site were the proximity of the railroad from Calais to Saint-Omer, the Aa river, important roads and the electricity network. Located at 177 km from London and 21 km from the coast, it was out of range of the guns of battleships and the northern part was partially protected by a 90m ridge. In the neighboring town of Saint-Omer an important Luftwaffe airbase could give air defence over the zone. Several sand- and gravel quarries and cement factories in the vicinity of the site provided the huge amount of necessary materials for the building works. Indeed, the plans projected the use of up to 200.000 tons of concrete and 20.000 tons of steel. When the American Major-General Lewis H. Brereton inspected the site after the war, he described the blockhaus as a 'conrecte construction bigger than anything else in the United States, apart maybe from the Hoover-dam'.

  Air view of the blockhaus  (IGN)


The plans for the site were drawn in January and February 1943 by engineers of the research center of Peenemünde and the Todt-organisation. On March 25, 1943, the plans were submitted to Hitler who approved them immediately. The end of the construction works was foreseen at the end of July and the site fully operational on November 01, 1943.

The blockhaus at Éperlecques was to be build following the B.III-2a concept but at a bigger scale. Initially the Germans had the intention to build a separate liquid oxygen factory at Stenay but this option was abandoned in favour of a factory within the blockhaus.

It was made up of three main sections. The central one of 90m wide and 28m high was to accommodate the liquid oxygen factory, the storage of the missiles and the preparation rooms. The walls were 7m thick and the installations went down to 6m underneath the ground surface. Five Heylandt compressors, capable of each producing 10 tons of liquid oxygen a day of which 150 tons had to be stored on the site. The complex was build to contain up to 108 missiles and enough fuel to organize three consecutive launching days as the Germans intended to launch 36 missiles per day (some sources state even 70 launches per day). The northern part of the construction had to expand over a railway station connected to the Calais - Saint-Omer railroad through a 1,2km junction from Watten. The missiles, warheads and other necessary equipments were to be delivered to the railway station and transported on trolleys into the bunker. There the rockets would be assembled, raised up to vertical, fueled,  armed and transported to one of the extremities of the building through 18m high rotating doors before coming out at the southern part of the structure and deployed onto the launch pad. These passages to the outside had no doors and chicanes were built in to attenuate the blast of the rockets. Launches were to be supervised from a control tower located at the southern part and overlooking the launch site.



6.000 workers of the 434 building battalion started the construction in March 1943 following the plans of Franz Xaver Dorsch, building director of the Todt-organisation. The manpower was made up of German specialists, French civilian recruited by force within the frame of the mandatory labour and Belgian, French, Dutch, Polish, Soviet and Tjechoslovakian prisoners of war. Numerous workers were French political prisoners and Spanish republicans who fled to France after their defeat during the Spanish War. Non German workers lived in two camps officially named 'Organisation Todt Watten Zwangsarbeitslager' (forced labour camp 62) about 2km from the site near the village of Éperlecques. These camps were controlled by the French police supported by Belgian and Dutch Nazis and volunteering Soviet prisoners of war and although escape attempts were punished with their death sentence, up to three persons escaped each day with some external help. More than 35.000 foreign workers worked on the site in groups of 3.000 to 4.000 persons on 12 hours shifts during the six months of its construction. Construction works continued 24 hours a day without any disruption and heavy lighting was used during the night. Those conditions were really harsh for the political prisoners and the workers of Eastern Europe. Getting sick for a non German worker or being unable to work following a heavy injury equaled the death sentence for them as they were or left on their own or sent back to their originating camps.

Construction materials were transported to Watten by barges and trains and unloaded onto a railroad at Decauville before going to the construction site where concrete-mixers turned night and day. A spacious storage facility was erected at Watten near the Aa river and was finally used to store the necessary materials for all the V2 sites in the Saint-Omer region. An electrical line of 90 KV was connected to a transformer in Holque, north of Watten, to supply the whole construction site. Work also started at Wizernes, about 12 km south of Watten, where an ancient quarry was chosen as a storage place for the needed equipments for Watten. A broad sidetrack was laid down to connect the quarry, codenamed “Schotterwerk Nord West” (gravel quarry North West) to the main track.

The site was initially supplied through the electric grid but the Germans built a generating station providing 1,5 MW at the northern part of the site to provide the blockhaus with its own electrical power limiting the risks of interruptions.
A radar site was installed at Prédefin, 35 km to the south, equipped with a Würzburg radar to monitor the trajectories of the launched V2 and evaluate their precision.

The allies discover the site

At the beginning of April 1943, an allied agent reported on the excavation of 'huge trenches' on the Watten site and on May 16, 1943, reconnaissance photography's of the Royal Air Force led allied specialist to conclude non identified activities were on their way at the site. Other big complexes were build in the Pas-de-Calais with unknown roles. Lord Cherwell, scientifical adviser of Winston Churchill, admitted he ignored what these big constructions similar to canon pads were but said that : 'if the enemy takes the trouble to built these construction it then would be useful for us to destroy them'.

At the end of May, the Comittee of British Chiefs of Staff ordered aerial attacks on these sites. On August 06, Duncan Sandys, responsible of the British armament, also recommended the attack on the site at Watten as the works were advancing quickly. The Committee of Chiefs of Staff intended daylight bombing missions with American bombers even though the American Staff considered Watten had nothing to do with missiles and was only a 'secured operations center'.


Desctruction of the site

On August 27, 1943, 187 American bombers B-17 of the 8th USAAF attacked the site with devastating effect. The fortified railway station at the northern part of the blockhaus was heavily damaged as the concrete had just been poured. Later, Walter Dornberger, wrote that the site , after the attack, was just a "devastated heap of concrete, steel, struts and wooden boards. The concrete hardened out and after a few days the structure was beyond repair. All we could do was to put on a roof and use it for another purpose". The bombing killed and wounded hundreds of labour workers. The Allies had tried ti minimize the collateral damage organizing the bombing raid during a shift change over, but the latter had been modified ny the Germans who were willing to obtain the working quotas of the day. The French pilot René Mouchotte, taking part in the escort of the first wave, was killed in aerial combat during this mission.

Only 35% of the blockhaus of Éperlecques was built then but it became evident it could not be used as a launch site anymore. The Germans were although still in need of liquid oxygen factories to supply to other V2 missile sites. After evaluating the damages in September and October 1943, the engineers of Organisation Todt concluded the northern part was damaged beyond repair and decided to concentrate on finishing the southern part of the site and transform it into a liquid oxygen factory. One of the engineers, Werner Flos, proposed to protect the construction by first building the roof which was done with a concrete paving of 5m thickness and weighing 37.000 tons. This paving was then raised by jacks and the new walls built underneath this new roof. The new liquid oxygen factory would be used to supply a launch site, far more important than Watten and mint to replace this latter, under construction at Wizernes. The thickness of the roof paving was calculated in the assumption that no allied bomb could penetrated such a thickness, but the Germans were unaware of the existence of the British seismic bombs.

The German attention turned towards Wizernes but the allies kept on bombing the Watten site. These attacks caused little damage to the blockhaus but railroads and roads were systematically destroyed. On July 03, 1944, the Oberbefehlshaber West authorised the end of the works at Watten and Wizernes sites which by then were heavily damaged. Three days later the interior of the blockhgaus of Éperlecques was devastated by a Tallboy bomb and on July 18, Hitler ended definitevly the construction works on bunker missile launch sites. Gerd Von Rundstedt, commander of the Western front, however decided to continue some works to delude the Allies. As the site had become useless, the Germans ironically named it 'Concrete Clod' and all liquid oxygen production equipment was moved the the V2 factory at Mittelwerk in Germany as the compressors were to vulnerable to the impact of a Tallboy.

The site at Watten was captured by the Candian Forces on September 04, 1944, which the Germans fled a couple of days before. But before fleeing they removed the water evacuating pumps so a great part of the blockhaus was inaccessible to the Allies. The blockhaus was again targeted by the Allies in February 1945 to test the penetration capability of the new Disney-bomb, designed to double the impact velocity and, in doing so, increase the penetration capability of the projectile.
The site had been chosen in October 1944 as it was the biggest accessible target in occupied territory and away from civilian areas. On February 03, 1945, a B-17 of the 8th USAAF dropped a Disney-bomb which slammed into a portion of the roof. The results however were not conclusive as the Royal Air Force was unable to determine the penetration capability into concrete. Although Disney-bombs were sometimes used during combat, their contribution to the war effort was rather minimal. In January 2009, the Disney-bomb was removed from the roof where she embedded herself during the test.
  The site like it was when the Canadian forces took it (Canadian Heritage)

Bombing of the Watten site


August 27, 1943: 187 B-17 of the 8th Bomber Command dropped 368 bombs of 910 kg on the Watten site. As the Allies thought it was a V1 complex, the pilots were ordered to bomb the freshly poured concrete at low altitude. The bombing resulted in the concrete to harden out in a shapeless mass beyond repair. The Allies lost two B-17, one shot down by Bf-109 fighters and the other, damaged by the Flak, crashed in the United Kingdom. Three P-47 were also shot down. 

August 30, 1943: 24 B-25, 18 Ventura and 36 B-26 of the 8th Bomber Command dropped 49 tones of bombs onto, what was described as an ammunition depot at Éperlecques. One bomber was shot down by Flak and fourteen others damaged. 

September 07, 1943: 58 B-17 dropped 116 tons of bombs on Watten. 

February 02, 1944: 95 B-24 escorted by 183 P-47 attacked the sites of Watten and Siracourt. 

February 08, 1944: 110 B-24 dropped 364 tons of bombs on Watten and Siracourt and more than 200 B-26 returned the next day. 

March 19, 1944: 117 B-17 bombed Watten, Wizernes and Mimoyecques and 65 A-20 attacked the sites again in the afternoon. 

March 21, 1944: 56 B-24 bombed Watten but the bad weather prevented the B-26 to participate in this raid. 

March 26, 1944: 500 heavy bombers from the 8th USAAF attacked sixteen German ballistic sites in northern France, including Watten and dropped 1271 tons of bombs. Four B-17 and one B-24 were shot down, 236 others were damaged.

March 29, 1944: 77 B-24 were sent out against Watten but due to mechanical and navigational problems only 31 were able to bomb the target. 

April 06, 1944: Five groups of B-24 from the American 2nd Bombardment Division attacked Watten but due to the bad weather only 12 planes made it to the target. 

April 18, 1944: Bombing of Watten by American airplanes. 

April 19, 1944: 27 B-24 attacked Watten during the afternoon. 

May 01, 1944: More than 500 heavy bombers were sent out to attack the ballistic sites in the Pas-de-Calais but the bad weather permitted only 129 of them to bomb Watten and Mimoyecques. 
May 30, 1944
: Heavy bombers of the USAAF targeted Watten and Siracourt.

June 16/17, 1944: 236 Lancaster and 149 Halifax from the RAF lead by 20 targeting Mosquito attacked the ballistic sites in the Pas-de-Calais, including Watten which was bombed with Tallboys for the first time.
June 18, 1944
: 58 B-17 bombed Watten

June 18/19, 1944: 10 Mosquito attacked Watten despite the bad weather. The results of these attacks are unknown but no aircraft was lost. 

June 19, 1944: 19 Lancaster enlighted by 11 reconnaissance Mosquito attacked Watten. The bad weather hampered the precision and the Tallboy which came the closest to the target missed it by 46m. 

July 06, 1944: 314 Halifax, 210 Lancaster and 26 Mosquito bombed the ballistic sites in the Pas-de-Calais, including Watten. The blockhaus was penetrated and severely damaged by a Tallboy. 

July 25, 1944: 81 Lancaster and 11 Mosquito attacked Watten and two other launch sites with Tallboy bombs. 

August 04, 1944: First mission of operation Aphrodite during which radio-controlled B-17 filled with explosives were used against Watten and other sites in the Pas-de-Calais but none of these aircraft hit the targets. 

August 06, 1944: Two other radio-controlled B-17 were sent to Watten but without great results.



In memoriam

Cdt René Mouchotte (Coll SBAP)

The site visit


The gigantic blockhaus

Damage after bombing missions  

Visit of the site, impressions...


The first thing quite remarkable when arriving on the site is the atmosphere created at the entrance by the arrival of the labour workers by train. The acces to the bunker is done through a little tour with an overview of the fundaments of the Atlantic Wall (beach defences, radar principles, explanations on the V1 and V2,...).

One of the most impressive facts is the change in building tactics designed by the organisation Todt to withstand the bombardments and irreparable damages. Instead of building the walls and than the concrete paving for the roof, they first built the concrete paving and lift it up with jacks to build the walls underneath it. The Germans were so in need of concrete they built a cement factory on site. This factory was mainly manned by young Belgian deported workers and a tablet sits on the remains of the factory to commemorate these Belgian labour workers. Inside the bunker is a full scale V2 putting forward the impressive size of this futuristic craft but created to bring a maximum of death... Observing the bomb wholes and damages done to the bunker, one can very realistically imagine what a hell this must have been during the bombardments. Outside the bunker you will find a launching ramp for the V1. The ramp you see here is partially dismantled regarding renovation works in progress but the presented V1 is complete. Aft of the launching system is a peg used to launch the V1 through a vapor propsulsion system comparable to the catapults found on aircraft carriers. To conclude the visit a couple of anti-aircraft defences are presented on the way out of the site.The feeling that stays within after visiting the site, is the hugeness of the installations, the incredible genius of the German engineers but most of all the feeling this site was a factory where death was omnipresent...


Citroën "Traction Avant"...strange place for a car


V2 rocket

V2 were designed in the experimental station of Peenemünde under the technical direction of the German engineer Werner Von Braun. The letter 'V' normally meaning 'Versuch' (prototype) in this case ment 'Vergeltung' or 'Vergeltungswaffe' (retaliation and retaliation weapon). The V2 were indeed launched as an answer to the allied bomb raids.

The V2 could have been used in Sicily in 1944 to counter the American treath, but the mission was aborted due to the high number of Italian soldiers in the zone.

The first succesful flight of a V2 (still codenamed A4 at that time) was on October 03, 1942 after two failed attemps on June 13 and August 16, 1942.

On this October 03, while the situation was becoming critical to the program, a fourth prototype urgently modified, flew a distance of 1.926km, describing a parabole with the culminating point at an altitude of 85km.

"This day will be, without a doubt, a crucial turning point within the technical evolution. Not only did our rocket enter space, but we used it to connect two terrestrial points. Prove is given that the rocket is a navigational in space. Same as the water, the earth and the air, space will become the theatre of intercontinental laisons and as such will acquire a great political importance. October 03, 1642 is the first of a new era in transportation, that of space travel. As long as the war lasts, our most urgent task can only be the rapid perfection of the rocket as a weapon. The development of capabilities we can not yet envisage will be a peacetime task". Speech of Walter Dornberger on October 03, 1942 in Peenemünde.

In fact the V2 did not reach space as such, but were the first rockets to leave the troposphere and reach the upper limits of the mesosphere. At this altitude gas molecules are no longer submitted to the earth gravitation and this is why it was considered the V2 reached space, although in the lower limits.

This success however remains an achievement completed only 40 years after a 'heavier than air', meaning an aircraft an not a balloon, took to the skies. Dornbergers speech was also prophetic as the knowlegde gathered within the V2 program would some years later allow the development of the American and Soviet space industry and moreover the conquest of the Moon.

The V2's were production built in an underground factory of the Dora Mittelwerke and tested at Blizna. From 1944 on, the V2 were operational as ballistic missiles but did not give the Germans the awaited superiority during the Second World War, meanly due to their lack of precision (sometimes several kilometers) and their rather small devastating effects 'only' carrying 750 kg of regular explosives. In return, due to its velocity and flight altitude, the V2 was only vulnerable during a couple of seconds, the take-off. None was intercepted.

A first launch was planned on September 06, 1944, from the 'Plateau des Tailles' in eastern Belgium not far from Sankt-Vith, but technical problems and the Allies already having passed the Meuse, forced the Germans to move nearer to their borders and so the first V2 launched was on September 08, 1944 from Gouvy (Belgium) towards Paris. In less than 5 minutes it reached Maisons-Alfort, in the suburbs of Paris causing the death of 6 people and injuring 36 more. Paris had the fearsome privilege to become the first target being hit by a military ballistic missile.

Later on the same day the first V2 hit Chiswick in the London area, although on the eve Duncan Sandys, British chairman of the war cabinet Committee for defence against German flying bombs and rockets, stated during a press conference the battle of London was over apart from some last little glitches. It was only two months and more than two hundred explosions later the British Government communicated about the ongoing V2 attacks. The secret was more easily kept as, on the contrary of the V1 with its caracteristic sound, the V2 missiles arrived at speeds of Mach 3.5, well above the speed of sound and so in complete silence before they hit their targets. Explosions were said to have been caused by all kind of things. After the first V2 on London, nobody understood what happened and one thought of an explosion of a building due to a gas leakage untill the discovery of the tailpipe.

In all, some 4.000 missiles were build in harsh condition for the prisoners assigned to these labour works (a.o. underground factory at Dora). The missiles were mend to be launched on the United Kingdom and London. The V2 killed twice more deportees in Germany than civilian in the United Kingdom.

Brought into service quite lately, the V2 were launched from sites which the Germans had to move several times due to the advance of the allied troops. In the Netherlands from the Middelburg region and Den Haag, as to reach London, than to Rijs (Norfolf regions), Hellendorn and Dalsfem (towards Belgium). In Belgium and Rhineland V2 were launched from Sankt-Vith and Mertzig towards Paris, moving to Koblenz, Euskirchen and Hachenburg for launches towards northern France and Belgium. The last launch sites were installed in the Münster region targeting Antwerp and Liège in Belgium.

Despite the damages to the fabrication infrastructures and launch sites 1.560 V2 were launched between September 08, 1944 and the end of 1944, mainly towards London (450) and Antwerp (920) - where 561 people were killed on December 16, 1944 when a V2 hit the movie-theatre Rex. But V2 were also launched towards Norwich (40), Liège (25), Paris (20) as well as on Lille, Tourcoing, Arras, Maastricht, Hasselt, etc...The launch of 1.500 other V2 continued to March 27, 1945, mainly from Den Haag and still towards London and Antwerp and some other military targets. The last launches were onto Kent. In total 1.350 V2 fell on London and more than 1.600 on Antwerp, the victims mainly being civilians.

V2 launch pad at Peenemünde (Bundesarchiev)

Result after the Tallboy impact

  6 tons Tallboy
The massive Tallboy bomb (Courtesy IWM) Drop...(Courtesy IWM)
Different kind of bombs with the Tallboy (Coll SBAP)
The concrete piercing Disney bomb

The incrusted Disney bomb at Eperlecques. This one was removed in 2009!
(Courtesy Le Blockhaus site)

Just launched (RAF archives)  
Oxygen bottles stocking system abandonned by the Germans  
  The forced laborers were transported by train from the camp to the site
Zundapp KS 750 side car Israeli Half-Track M3 type
The Demag crane  
Decauville troley  
Mines-clearing Piglets U-boot "Bieber"
Beach obstacles remaining from the Atlantic wall British QF-25 Pounder
Bedford truck  
German 88mm gun 120mm WZ 1878-09-31, Polish gun but used by the Germans
The Swedish Anti-aircraft gun Bofors 40 mm
was placed along the British coast to shootdown the V1 flying bombs
Ward la France vehicle

Detection means...the radar

  Aircraft relic from the different attacks in the area

Flying bomb V1


The V or Fieseler Fi 103 was mainly designed named FZG 76, of the German Flak Ziel Gerät 76 by Robert Lusser from the Fieseler factory and by Fritz Gosslau from the Argus factory.

In July 1944 an RAF aircraft was able to land in Poland, embark an intact V1 provided by the Armia Krajowa (Polish Resistance) and fly it back to England. Experts than took note the craft corresponded to the descriptions made in 1942. Until the end of 1943, British and American services considered that such a weapon could not exist and even on June 10, 1944 the sceptics still held on to this idea.

From the spring of 1944, a piloted version of the V1, codenamed Reichenberg, is on project and modified examples are largely tested, among others by Hanna Reitsch, but none of these were used in combat. In this version the pilot had to fly the V1 to the target and parachute from the bomb at 1.000m from the target. Due to the shortage of time to eject from the craft, as the ejections were still entirely manual, these type of missions were similmar to suicide. A two-seat version was even foreseen for the training of the pilots. The landings was done on a 'ski' underneath the fuselage.

In February 1944, intelligence networks, such as the Marco Polo network, warned London Germans did some conclusive tests of airborne V1 launched from and aircraft. Heinkel He-111 bombers were used to launch this type of V1. These planes were based in the Netherlands and the launched V1 easely avoided the DCA (Défense Contre Avion - Anti-aircraft Defences). They continued their deathly actions until 1945, the last V1 falling on the village of Datchworth on March 29, 1945.


The engine of the V1 was a pulsejet attached to the aft fuselage by two beams. The fuselage contained the explosive charge, the fuel and an inertial platform providing a crude guidance system. Two little wings and a stabiliser with elevator completed the craft. Yaw was controlled by a rudder installed in the aft engine beam. The craft was catapulted from a ramp after ignitring the pulsejet by a gas-burner or dropped by a carrying-aircraft, after which the bomb was flying on her own. The 'drop-point' was approximately calculated and a primitive screw-device counter, set up before launch and driven by a litlle airscrew on the nose of the V1, cut the elevator cable. Two light explosive charges expanded two airbrakes underneath and on each side of this elevator putting the flying bomb in a dive. This sudden change of attitude often caused the engine to quit and the overflown populations listened to the specific sound of the pulsejet with anxiety, fearing the moment of 'silence' indicating the V1 was diving towards the ground.

The ramp  

The launch tube were the piston was placed.
The high pressure steam was produced by a chemical reaction between
Hydrogen peroxide and Permanganate


The piston

To the launch ramp (Bundesarchiv) Could be launched from a Heinkel He-111 plane (Bundesarchiv)
A mobile launch ramp destructed after  an air attack (courtesy IWM)
Some markings of the Eperlecques V1  
  A view like it was during the second world war (Coll SBAP)
More informations...click on the folder

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