page_title: Blockhaus d'Éperlecques
section_title: Design and location
hierarchical_section_title: Blockhaus d'Éperlecques / Design and location
caption_attribution_description: English: Diagrammatic representation of the Watten bunker complex. Fortified train station for missile and supplies delivery. Liquid oxygen storage. Transit halls. Servicing hall where the V-2s would be prepared for launch. Liquid oxygen production plant. Transit halls where V-2s would be transported to the launch pads Launch pads Launch control centre Standard gauge rail link to Calais-Saint-Omer railway line.
context_page_description: The Blockhaus d'Éperlecques is a Second World War bunker, now part of a museum, near Saint-Omer in the northern Pas-de-Calais département of France, and only some 14.4 kilometers north-northwest from the more developed La Coupole V-2 launch facility, in the same general area.
  The bunker, built by Nazi Germany under the codename Kraftwerk Nord West between March 1943 and July 1944, was originally intended to be a launching facility for the V-2 ballistic missile. It was designed to accommodate over 100 missiles at a time and to launch up to 36 daily.
  The facility would have incorporated a liquid oxygen factory and a bomb-proof train station to allow missiles and supplies to be delivered from production facilities in Germany. It was constructed using the labour of thousands of prisoners of war and forcibly conscripted workers used as slave labourers.
  The bunker was never completed as a result of the repeated bombing by the British and United States air forces as part of Operation Crossbow against the German V-weapons programme. The attacks caused substantial damage and rendered the bunker unusable for its original purpose.
context_section_description: In December 1942, Speer ordered Peenemünde officers and engineers (including Colonel Gerhard Stegmair, Dr Ernst Steinhoff and Lieutenant-Colonel Georg Thom) to tour the Artois region in northwest France and locate a suitable site for an A-4 launch facility. The site chosen was just to the west of the small town of Watten, in the Forest of Éperlecques, near Saint-Omer in the Pas-de-Calais department. It was given the cover name of Kraftwerk Nord West (Northwest Power Plant).
  The location was conveniently close to the main railway line between Calais and Saint-Omer, the canalised River Aa, main roads and electric grid lines. Situated 177 kilometres (110 mi) from London, it was far enough inland to be safe from naval guns and it was sheltered to an extent by a ridge that rises to a height of 90 metres (300 ft) to the north.
  At nearby Saint-Omer, there was a major Luftwaffe base which was capable of providing air defence for the area. There were existing gravel and sand quarries as well as cement works in the vicinity, which would help with the enormous amount of material that would be needed for the construction works. The quantities required were very substantial indeed; 200,000 tons of concrete and 20,000 tons of steel would be required to build the facility. When US Army Major General Lewis H. Brereton inspected the site after it had been captured by the Allies, he described the bunker as "more extensive than any concrete constructions we have in the United States, with the possible exception of Boulder Dam."
  The Watten bunker was to be built to a design based on the B.III-2a bunker, though substantially larger. The Germans had originally planned to build a separate LOX plant at Stenay but this option was abandoned in favour of installing a LOX production facility within the Watten bunker.
  The bunker consisted of three main elements. The main part of the building was a giant structure some 92 metres (302 ft) wide and 28 metres (92 ft) high, housing the LOX plant and a vault where missiles would be assembled and prepared. Its walls were up to 7 metres (23 ft) thick and the bunker's working levels descended 6 metres (20 ft) below ground. The plant would house five Heylandt compressors, each capable of producing about 10 tons of LOX per day. About 150 tons of LOX were to be stored in insulated tanks on-site. The facility was intended to store up to 108 missiles and enough fuel to supply three days' worth of launches. The Germans planned to fire up to 36 rockets a day from the site.
  On the north side of the building was a fortified standard gauge railway station, linked to the main Calais-Saint-Omer line at Watten via a 1.2 kilometres (0.75 mi) spur line. Missiles, warheads and other components would be shipped to the station and transported on trucks into the main area of the bunker. Here the rockets were to be assembled, raised into a vertical position and fuelled and armed. From the arming halls, they would be moved to either end of the building through pivoting doors 18 metres (59 ft) high. They would exit through the south face of the building and would be moved on tracks to the launch pads. There were no doors on the exit portals so chicanes were installed in the exit passage to deflect the blast of rockets being launched from outside. Launches would be overseen from a command tower located in the centre of the south side of the bunker, overlooking the launch pads.
  To the north of the bunker, the Germans erected a bomb-proof power station with a 2,000 horsepower (1.5 MW) generating capacity. The site was initially powered from the main electricity grid, but it was intended that it would have its own independent power source to minimise the likelihood of disruption. Also associated with the Watten complex was a radar tracking site at Prédefin, 29 kilometres (18 mi) south of Saint-Omer. A Giant Würzburg radar system was installed there to follow the trajectories of V-2s being launched from Watten. The intention was to follow the trajectory for as long as possible so that the accuracy of the missile launches could be dete
caption: Diagram of the original planned layout of the Watten bunker
   1. Fortified train station for missile and supplies delivery.
   2. Liquid oxygen storage.
   3. Transit halls.
   4. Servicing hall where the missiles would be prepared for launch.
   5. Liquid oxygen production plant.
   6. Transit halls lined with anti-blast chicanes, where missiles would be transported to the launch pads
   7. Launch pads
   8. Launch control centre
   9. Standard gauge rail link to Calais-Saint-Omer railway line.
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