Initially a sub-camp of KL-Buchenwald, the site of Mittelbau-Dora gradually became an independent Konzentrationslager, eventually with its own compliment of approximately 40 sub-camps, following the allied air attacks on the Peenemünde rocket facility during August 1943.
Due to the increased allied air raids, the Nazis chose to move many of their weapons and munitions facilities to underground locations, such as the one at the Kohnstein near Nordhausen. The site had previously been used as a fuel storage facility for the Wehrmacht, but much work was required in order to prepare the tunnel complex for use as a rocket manufacturing plant. Initially, for the first several months, the slave labour prisoners were even housed within the tunnel system, as the construction of the future camp was yet to be deemed important enough to become a priority. The relentless drive towards producing the new wonder weapons was the only concern of the hierarchy.
The Vergeltungswaffen (weapons of retaliation, or vengeance weapons as they are commonly referred to), were constructed within a massive tunnel complex, of which only 3-4% is actually accessible today. The entire system stretches some 20km, with some tunnel sections reaching a height of 30m.
The Konzentrationslager was built later, with the first batches of prisoners finally being housed in external barracks during January 1944, when production of the A4, later known by the propaganda name V2, rockets went into production. Even by late spring of 1944, some inmates were still kept within the tunnel system.
Upon completion of the manufacturing facilities, most of the prisoners were sent to the sub-camps to continue working on numerous underground projects, or were transported to camps in Poland where most were killed soon after. New prisoners, specially selected from throughout the Konzentrationslagers system, were transported to KL-Mittelbau-Dora to begin work on the manufacture of the new rockets.
Of the 60,000 prisoners incarcerated at KL-Mittelbau-Dora, conservative estimates reckon at least 20,000 did not survive. The average population at the main camp was 15,000. By spring 1945, the Mittelbau-Dora camp system held over 40,000 prisoners, mostly from the Soviet Union, Poland and France, although many Jews also arrived at Mittelbau-Dora from May 1944 onwards.
The camps were eventually vacated by the SS in early April 1945. Several thousand prisoners were transported to Bergen-Belsen by rail, with numerous other transports sending many other north to camps such as Ravensbrück and Sachsenhausen. The sub-camp at Aussenlager Boelcke-Kaserne, used from early 1945 as a camp for Mittelbau-Dora's sick and dying, was the site of thousands more victims, many of whom were sadly killed during an allied air attack on the Nordhausen area. The SS left very few prisoners at the main camp, with US troops finding only a few hundred present when they eventually liberated the camp on 11.4.1945. The Boelcke-Kaserne sub-camp however, was a different story, with more than 1,300 bodies found by American forces upon liberation.
KL-Mittelbau-Dora had two Kommandants, initially Otto Förschner and latterly Richard Baer, who replaced Förschner in February 1945, after he and the SS fled KL-Auschwitz. Baer had been the final Kommandant at Auschwitz-I.