The construction work began in May 1944 under the code name Dogger. The underground factory was planned to have an area of 120,000 square metres, as stated by Walter von Linden, director of the "Deutsche Schachtbau" (German Mine Shaft Construction), during one of the post-war trials. Under the guidance of 400 German miners, the prisoners had to work around the clock in shift operation. The companies AEG, Thosti, Tauber, Hochtief AG and Siemens Bau-Union were involved in the construction of the factory. Eight connected galleries were constructed by rock blasting. These contained factory halls five metres high and up to seven metres wide. Before the invasion of the US Army the mines reached a length of 4.03 kilometres. The prisoners had to walk a distance of 5 kilometres from the camp of Hersbruck to the construction site in Happurg every day.
Further reading
Шаблон:In lang G. Faul: Sklavenarbeiter für den Endsieg. Hersbruck 2003. (Published by the documentation center KZ Hersbruck e.V.)
