Between March 1944 and April 1945, there was a Neuengamme satellite camp in Barkhausen (Porta Westfalica), called Porta. This camp was housed in a banquet hall of Hotel Kaiserhof. About 1500 prisoners lived here who had to perform forced labor in underground factories.

And living and working here at the end of the Second World War was hell for more than 1500 concentration camp prisoners from all over Europe. From the spring of 1944 until the Allied advance at the beginning of April 1945, Russians, Poles, Italians, French, Belgians, Dutch and Danes toiled relentlessly here on orders from the SS, twelve hours a day. For many it was death.  400 to 500 died - here or in the "Kaiserhof", the former posh hotel on the other side of the Weser. The prisoners were crammed together in what used to be the ballroom, under strict guard and in the most miserable hygienic conditions. There were even executions in front of the assembled crew.

Hölle 1 was the name the prisoners gave to the Jakobsberg complex. It was called “Badger 1” in Nazi jargon, a code name for the relocation of wartime armaments production underground to avoid Allied bombing. According to the first plans from March 1944, the production of fighter pilots should be established in Porta. But shortly thereafter, after the bombing of the refinery in Hanover, the production of fuel and lubricating oil became important for the operation of machine tools in armaments production.

Most of the prisoners only wore wooden shoes. In addition, coarse, worn prisoner clothing, inadequate for the environment. And the food was even worse. The body needs 4800 kilocalories every day for heavy work. The SS allowed 3,600 – on paper. In fact, there were just 1200 kilocalories, mostly in the form of cabbage and vegetable soup, hardly any meat and protein. The result was wasting. One of the prisoners, the Danish medical student Jørgen Kieler, later analyzed and scientifically described the sequence of physical deterioration caused by the hunger syndrome with diarrhea and dysentery. Destruction through work – and malnutrition.

In order to extend and widen the existing tunnels to 150 meters, 60,000 cubic meters of rock had to be blasted and removed from the mountain. The latter was the task of the SS slaves - with shovels, manual work, wheelbarrows and carts. They then had to bring building materials into the tunnels. German masons built huge tanks there to hold the later lubricating oil products. None of the tanks saw a single liter of oil. Five weeks before the planned start of operations in May 1945,