Auschwitz concentration camp was a network of German Nazi concentration camps and extermination camps built and operated by the Third Reich in Polish areas annexed by Nazi Germany during World War II. It consisted of Auschwitz I, Auschwitz II–Birkenau, Auschwitz III–Monowitz, Auschwitz I was first constructed to hold Polish political prisoners, who began to arrive in May 1940. The first extermination of prisoners took place in September 1941, from early 1942 until late 1944, transport trains delivered Jews to the camps gas chambers from all over German-occupied Europe, where they were killed with the pesticide Zyklon B. An estimated 1.3 million people were sent to the camp, around 90 percent of those killed were Jewish, approximately 1 in 6 Jews killed in the Holocaust died at the camp. Many of those not killed in the gas chambers died of starvation, forced labor, infectious diseases, individual executions, and medical experiments. In the course of the war, the camp was staffed by 7,000 members of the German Schutzstaffel, some, including camp commandant Rudolf Höss, were executed. The Allied Powers refused to believe reports of the atrocities at the camp. As Soviet troops approached Auschwitz in January 1945, most of its population was sent west on a death march, the prisoners remaining at the camp were liberated on 27 January 1945, a day now commemorated as International Holocaust Remembrance Day. In the following decades, survivors, such as Primo Levi, Viktor Frankl, and Elie Wiesel, wrote memoirs of their experiences in Auschwitz, and the camp became a dominant symbol of the Holocaust. In 1947, Poland founded the Auschwitz-Birkenau State Museum on the site of Auschwitz I and II, immediately after the Nazi seizure of power in Germany, acts of violence perpetrated against Jews became ubiquitous. The Law for the Restoration of the Professional Civil Service, passed on 7 April 1933 excluded most Jews from the legal profession, similar legislation soon deprived Jewish members of other professions of the right to practise. Harassment and economic pressure were used by the regime to encourage Jews to leave the country voluntarily and their businesses were denied access to markets, forbidden to advertise in newspapers, and deprived of government contracts. German Jews were subjected to violent attacks and boycotts, in September 1935 the Nuremberg Laws were enacted. The Reich Citizenship Law stated that only those of Germanic or related blood were defined as citizens, thus Jews and other minority groups were stripped of their German citizenship. The laws were expanded on 26 November 1935 to include Romani people and this supplementary decree defined Gypsies as enemies of the race-based state, the same category as Jews. By the start of World War II in 1939, around 250,000 of Germanys 437,000 Jews had emigrated to the United States, Palestine, the United Kingdom, Nazi Germany invaded Poland in September 1939. German dictator Adolf Hitler ordered that the Polish leadership and intelligentsia be destroyed, approximately 65,000 civilians, who were viewed as being inferior to the Aryan master race, were killed by the end of 1939. In addition to leaders of Polish society, the Nazis killed Jews, prostitutes, Romani, sS-Obergruppenführer Reinhard Heydrich, then head of the Gestapo, ordered on 21 September that Polish Jews should be rounded up and concentrated into cities with good rail links
Image: Auschwitz birkenau main track
Map showing the location of the three main camps (1944). Prisoners: yellow; facilities: blue-gray
American surveillance photo of Birkenau (1944). South is at the top in this photo.