With Germany's quick victory over Poland, there was a division of territory according to an earlier agreement between Hitler and Stalin. The eastern portion of Poland would be given to the Soviet Union. There would be a central buffer zone, and the western portion of the country would become part of Germany.
The SS immediately began looking for a location in which to establish a prison, predominantly for political prisoners. The suggested location featured 22 pre-existing brick barracks buildings on the outskirts of Oswiecim, that had previously served the Polish Army. Walter Eisfeld, former commandant of Sachsenhausen, was sent to inspect the site, and in April, 1940, formal approval was given by Himmler.
Rudolf Hoss was appointed commandant and was sent to oversee development of the new facility. Approximately 17,000 local residents were displaced, some to make room for further expansion plans, and other to make room for German citizens enticed to move to the area.
In May, 1940, 30 prisoners from Sachsenhausen were sent to Auschwitz to become functionaries. By June 14, 1940, the prison was ready to accept 728 Polish political prisoners from a prison in Tarnow.
By its peak in the summer of 1944, the entire Auschwitz complex would cover 40 square kilometres and imprison almost 135,000 people, accounting for about 25% of all people in the entire camp system.
Because of it's vast size, Auschwitz was split into three, largely autonomous camps, Auschwitz I (main camp), Auschwitz II (Birkenau) and Auschwitz III (Monowitz).
In November, 1944, with the approach of the Soviet Red Army, Himmler ordered the evacuation of the prisons directing that not one prisoner would make it alive into the hands of the enemy. As a result, all who were able were subjected to a death march to the Bergen-Belsen concentration camp.
When the Russians entered the camp, they found about 600 corpses, and about 7,500 living who had been left behind as too sick to make the trip. Also found were 370,000 men's suits, 837,000 women's garments, and 7.7 tonnes of human hair.
Auschwitz I became a hospital for liberated prisoners. Polish and Soviet investigators worked here to document SS war crimes. Other parts of the facility were used as a Soviet prison camp, repeating many of the atrocities committed by the SS.
Most of the former staff were tried and executed for war crimes, including the commandant, Rudolf Hoss who was eventually hanged at Auschwitz.