The Auschwitz concentration camp complex was the largest one established by the Nazi regime. It included three main camps, all of which used prisoners for forced labor. One camp also functioned as a killing center. Construction began at Auschwitz (approximately 37 miles west of Krakow, Poland) in May 1940. It is estimated that the SS and German police deported at minimum 1.3 million people to the Auschwitz complex between 1940 and 1945. Of these, the camp authorities murdered 1.1 million people.
Construction of Auschwitz II, or Auschwitz-Birkenau, began in October 1941. Of the three camps, Auschwitz-Birkenau had the largest total prisoner population and also contained the facilities for a killing center. It played a central role in the German plan to kill the Jews of Europe, using Zyklon B gas for mass murder. Eventually, four large crematorium buildings were built from March-June 1943. Each had three components: a disrobing area, a large gas chamber, and crematorium ovens. The SS continued gassing operations at Auschwitz-Birkenau until November 1944.
From 1942 to the end of summer 1944, trains arrived at Auschwitz-Birkenau with transports of Jews from virtually every country in Europe occupied by or allied to Germany. In total, approximately 1.1 million Jews were deported to Auschwitz. SS and police authorities deported approximately 200,000 other victims to Auschwitz, including 140,000-150,000 non-Jewish Poles, 23,000 Roma (Gypsies), and 15,000 Soviet prisoners of war.
New arrivals at Auschwitz-Birkenau underwent selection. The SS staff determined the majority to be unfit for forced labor and sent them immediately to the gas chambers, which were disguised as shower installations. At least 960,000 Jews were killed in Auschwitz. Also murdered were approximately 74,000 Poles, 21,000 Roma (Gypsies), 15,000 Soviet prisoners of war, and 10,000-15,000 of other nationalities (Czech, Yugoslav, French, German, and Austrian).
Auschwitz III, also called Buna or Monowitz, was established in October 1942 to house prisoners assigned to forced labor at rubber works owned by the German conglomerate I.G. Farben. Between 1942 and 1944, the SS authorities at Auschwitz established 39 subcamps. Inmates were forced to work in coal mines and in armaments industries. Some were tattooed with identification numbers on their left arms. If the SS judged prisoners too weak to continue with forced labor, they were transported to Auschwitz-Birkenau and killed.
In mid-January 1945, as Soviet forces approached, the SS destroyed the remaining gassing installations and began evacuating Auschwitz. SS guards forced nearly 60,000 prisoners to march west and shot anyone who fell behind. Prisoners also suffered from starvation and exposure and as many as 15,000 prisoners died during the evacuation marches from Auschwitz. Thousands were also killed in the camps in the days before the evacuations. On January 27, 1945, the Soviet army entered Auschwitz and liberated around 7,000 prisoners, most of whom were ill and dying.