At the end of 1944, the SS began to evacuate the inmates of Auschwitz and Gross-Rosen before the advancing Red Army. Many of them were transported to the Mittelbau. Through March 1945, up to 16,000 prisoners arrived, including women and children. Although many died in transit, this raised the number of Jews at Mittelbau. Those who survived were often extremely weak or sick. Once again, the death rate rose: Between January and early April 1945, around 6,000 inmates died, around 3,000 of them at the "Boelcke-Kaserne" (a former Luftwaffe barracks) at Nordhausen, which had been used by the SS after January 1945 as the main "Sterbelager" (camp for the dying) for the Mittelbau system. Also from January to April 1945, at least 1,700 V-2 and over 6,000 V-1 rockets were built.