Mittelbau-Dora (also Dora-Mittelbau and Nordhausen-Dora) was a Nazi concentration camp located near Nordhausen in Thuringia, Germany. It was established in late summer 1943 as a subcamp of Buchenwald concentration camp, supplying slave labour from many Eastern countries occupied by Germany (including evacuated survivors of eastern extermination camps), for extending the nearby tunnels in the Kohnstein and for manufacturing the V-2 rocket and the V-1 flying bomb. In the summer of 1944, "Mittelbau" became an independent concentration camp with numerous subcamps of its own. In 1945, most of the surviving inmates were sent on death marches or crammed in ox train-cars by the SS. On 11 April 1945, US troops freed the remaining prisoners.