While the two massive British air attacks that targeted Nordhausen did not trigger the evacuation of the Mittelbau camps, they substantially accelerated it. The process of evacuating the parent camp Dora began on the evening of April 3, when 4,000 Soviet inmates were sent to Bergen-Belsen by rail. The officers in charge of the other Mittelbau camps must have received the pull-out order from Dora on or around April 4, as most of the camps were vacated on April 4 and 5.
The tortures suffered by the inmates from Auschwitz and Gross-Rosen in the context of those camps’ dissolution in January and February 1945 were now repeated: in a great hurry and with the utmost brutality, the guard details drove the inmates into the freight and cattle cars that had been obtained. By April 6, 1945, several trains, each bearing thousands of inmates, had left the Southern Harz Mountains for Bergen-Belsen, Sachsenhausen and Ravensbrück. Driven by guard details, numerous gangs of exhausted inmates also dragged themselves on foot through the mountains towards the northeast.
On these marches of violence, anyone who could not keep up was simply shot to death from behind by the guards. Most of the Mittelbau subcamps were completely evacuated. The SS left only a few hundred ill and dying persons behind in Dora and the Boelcke Casern; these inmates were liberated by the U.S. Army on 11 April 1945.