It had seven gas chambers, two wooden gallows, and some 227 structures in all, placing it among the largest of Nazi-run concentration camps.[2] Although initially purposed for forced labor rather than extermination, the camp was used to kill people on an industrial scale during Operation Reinhard, the German plan to murder all Jews within their own General Government territory of Poland.[3] The camp, which operated from October 1, 1941, until July 22, 1944, was captured nearly intact, because the rapid advance of the Soviet Red Army during Operation Bagration prevented the SS from destroying most of its infrastructure, and the inept Deputy Camp Commandant Anton Thernes failed in his task of removing incriminating evidence of war crimes. Therefore, Majdanek became the first concentration camp discovered by Allied forces.[4] Also known to the SS as Konzentrationslager (KL) Lublin, Majdanek remains the best-preserved Nazi concentration camp of the Holocaust.[5]