Valentin submarine pens

The Valentin submarine factory is a protective shelter on the Weser River between the Bremen suburbs Rekum and Farge, built to construct German U-boats during World War II. The factory was under construction from 1943 to March 1945 using forced labour, but was damaged by air-raids and unfinished by the end of the war. The Valentin factory was the largest fortified U-boat facility in Germany, and was second only to those built at Brest in France.

As a manufacturing facility, it differed from conventional U-boat pens, which were designed to house and service operational U-boats.

Construction
Production of U-boats by German shipyards had been dramatically reduced by bombing by the Royal Air Force and the United States Army Air Forces. So many bomb-proof production sites were in 1944 already in use; for example the U-boat pen Nordsee III on the German island of Heligoland, Fink II and Elbe II in Hamburg and Kilian in Kiel, under construction or planned as Hornisse in Bremen, Elbe XVII and Wenzel in Hamburg, Wespe in Wilhelmshaven, Kaspar in Kiel and others in Germany and in occupied countries. Under the codename Valentin a submarine factory was to be built directly on the Weser river between the Bremen suburbs Rekum and Farge. It was intended the facility would be used for the final assembly of Type XXI submarines, starting in April 1945 with three boats and from August 1945 a monthly delivery of a minimum of 14 boats. Besides this, a further bunker called Valentin II was already planned.

The bunker is around 426 m long and 97 m wide at its widest point; the walls are 4.5 m thick. The height of the structure is between 22.5 and 27 m. The roof was constructed using dozens of large, reinforced concrete arches, manufactured on-site and individually lifted into place. Most of the roof is around 4.5 m thick but part of it is 7 m thick as the Germans began adding to its thickness before the bunker was even completed. Construction required 650000 cuyd of concrete.

After completion, the bunker would have had a work–force of around 4,500 slave workers. Under the management of the Bremer Vulkan shipyard, each U-boat would have been assembled from eight, large, pre-fabricated sections manufactured in other shipyards such as Bremer Vulkan, Deschimag AG Weser with its bunker Hornisse, Kriegsmarinewerft Wilhelmshaven with bunker Wespe and Deschimag Seebeckwerft in Bremerhaven, and then shipped to Valentin on barges.



Use
The bunker was to house 13 assembly bays (called Takt 1–13 in German), each carrying out one part of the assembly process. Two bays, (Takt 9/10), were underneath box-like structures on the roof that allowed the extra height needed for the installation of periscopes, snorkels (an underwater engine functioning and crew breathing device) and antennas. The two last bays, (Takt 12/13), were separated by high walls from the others and could be closed by water-tight floodgates. The final bay, (Takt 13), was a dry dock with an 8 m deep pool of water. The two separated bays could be flooded to altogether about 20 metres height from the bottom of the dock to the water-surface. When the floodgates were closed the boats would be launched from Takt 12 to Takt 13 and leak–tests of the completed U-boats as well as engine starts and several other tests were carried out in the dock Takt 13. Besides these assembly bays, there were several workshops and store-rooms for the prefabricated sections, diesel-engines and batteries, and tanks for fuel and lubricants.

The gateway in the western wall could be closed by means of a sliding bomb-proof door which opened to a small canal, a creek and then directly onto the Weser river. Through this, sections of submarine would be delivered by barges and completed submarines could leave.

It was intended that Valentin would commence production in late 1944, but this was postponed to mid-1945. However, if Valentin had been commissioned, it is likely that production would have been limited, unless severe quality control problems with the prefabricated sections could have been solved. (Albert Speer [the Reich armaments minister] had directed the sections should be made by inland companies with little experience in shipbuilding). The Type XXI submarines assembled in other shipyards required lengthy re-working to fix flaws in the sections; out of the 118 boats completed, only four were rated fit for combat before the war ended in Europe. The design and oversight of the Valentin's construction was carried out by the Organisation Todt. Marineoberbaurat Edo Meiners was in charge overall; the on-site supervising engineer was Erich Lackner. He had a lengthy post-war career, becoming one of Germany's most important civil engineers.

Labour force
Most of the 10,000–12,000 people who built Valentin were slave workers, who lived in seven camps located between 3 and 8 km from the bunker. Some were housed in the nearby Bremen-Farge concentration camp, a satellite of the Neuengamme concentration camp complex. The camp was sited at a large naval fuel oil storage facility; some prisoners were accommodated in an empty underground fuel tank.

The camp was initially run by the SS, but the expansion of the camp network in the area led to a shortage of personnel. By the summer of 1944, the camp was commanded by an army captain, Ulrich Wahl, and the prisoners were guarded by a detachment of naval infantry. Only a handful of SS men remained involved in the running of the camp.

The prisoners included German criminals and political prisoners, non–German civilian workers (Fremdarbeiter) as well as Russian, Polish, and French prisoners of war.

Work on the bunker took place around the clock, with personnel forced to work 12-hour shifts from 7am to 7pm. This resulted in a high death rate amongst the prisoners. However, the identity of only 553 victims, mostly Frenchmen, has been confirmed. The total number of deaths may be as high as 6,000 as the names of the Polish and Russian dead were not recorded. The worst work on the site was that of the so-called iron detachments (Eisenkommandos), responsible for the movement of iron and steel girders. A French survivor, Raymond Portefaix, stated that a prisoner's life expectancy fell dramatically on being assigned to one of these detachments. He described the Eisenkommandos as suicide squads. By March 1945, the facility was 90% completed and the most of the necessary machine tools had been installed. Production of U-boats was due to begin within two months.

Bombing
The Valentin factory was attacked by the RAF on 27 March 1945. The attacking force consisted of twenty Avro Lancaster heavy bombers of 617 Squadron which had, after the "Dambusters" raid, developed precision bombing methods. Simultaneously, a force of 115 Lancasters bombed the nearby fuel oil storage depot in the village of Schwanewede. The bombers were escorted by ninety RAF North American Mustang fighters of 11 Group

The Lancasters attacking Valentin each carried a single, large earthquake bomb – seven carried the 5 ton 'Tallboy', thirteen carried the 10 ton 'Grand Slam'. Two 'Grand Slam's hit the target and penetrated about half-way through the 15 ft thick ferrous concrete roof before exploding. The explosions blew large holes in the remaining thickness of the roof and brought down around 1,000 tons of debris into the chamber below. Workers who were inside the bunker at the time survived, as the bombs did not penetrate the roof before detonating. Another bomb caused damage to a nearby a electricity plant, workshops and a concrete mixing plant.

Fortunately for the British, the two bombs struck and penetrated the 4.5 m thick west section of the roof. Post–war, American analysis suggested the 7 m thick, east section would have been able to resist even the Grand Slams, although not without significant damage, and it is unlikely that it would have survived repeated hits.

Three days later, on 30 March, the US Eighth Air Force attacked Valentin with Disney bombs. These were large (4500 lb) weapons with hard steel casings, rocket-assisted to increase their penetrating power. Sixty were launched but only one hit the target, causing little damage. However, considerable damage was done to installations surrounding the bunker.

The factory was abandoned, and four weeks after the bombing, the area was occupied by the British Army's XXX Corps, which captured Bremen after a five-day battle.

The prisoners held at the Neuengamme concentration camp and its subcamps were evacuated before the arrival of the British. Many were placed on board the SS Cap Arcona. This German ship was heavily laden with around 5,000 concentration–camp prisoners when she was attacked and sunk by the RAF on 3 May 1945; only 350 prisoners survived.

It is estimated that more than 6,000 workers died during the building of Valentin.



Post war
After the war, when the already installed machine tools had been removed, further bombing of Valentin was carried out. Beginning in March 1946, Project Ruby was a joint Anglo-American affair to investigate the use of penetration bombs against heavily protected, concrete targets.

The U-boat pen Nordsee III and subterranean bunkers on the island of Heligoland were also selected as targets for this testing. Bombs were carried by Avro Lancasters from No. 15 Squadron RAF and US Boeing B-29 Superfortress and Boeing B-17 Flying Fortress aircraft operating from RAF Marham. Around 140 sorties were flown, testing a range of different bombs.

Because it seemed impossible to destroy Valentin by bombing it, the decision was made to destroy it by blasting. This idea was later given up because the blasting would have caused severe damage in the nearby villages of Rekum and Farge and the power-station in Farge. In the following years, there were several ideas for the further utilization of the bunker, for example the creation of an artificial hill using rubble from the bombed cities, or using it as an atomic power station, but in 1960 the bunker was taken over by the German Navy, for use as a storage depot.

In 1983, a memorial to the workers who built Valentin was erected. Titled Vernichtung durch Arbeit (Extermination through labour), it was by Bremen artist Fritz Stein.

High maintenance costs forced the German Defence Ministry to offer the bunker for sale in 2008. Military use finally came to an end on 31 December 2010. Its custodianship was passed to a group called Denkort Bunker Valentin with the intention of developing it as a museum and a memorial. The group currently offers guided tours of the bunker to the public.