In the immediate postwar period, Mengele was in US custody. Unaware that Mengele's name already stood on a list of wanted war criminals, US officials quickly released him. From the summer of 1945 until spring 1949, using false papers, Mengele worked as a farmhand near Rosenheim, Bavaria. His prosperous family then aided his emigration to South America. He settled in Argentina.
In the autumn of 1941, SS chief Heinrich Himmler assigned German General Odilo Globocnik (SS and police leader for the Lublin District) with the implementation of a plan to systematically murder the Jews of the Generalgouvernement. The code name Operation Reinhard was eventually given to this plan, named after Heydrich (who was assassinated by Czech partisans in May 1942). As part of Operation Reinhard, Nazi leaders established three killing centers in Poland—Belzec, Sobibor, and Treblinka—with the sole purpose of the mass murder of Jews.
Britain's attitude to Jewish refugees from Nazi-controlled areas was strongly influenced by its role as the mandatory power in Palestine, where it had to mediate between Jewish and Arab interests. In December 1941, the Struma, a ship carrying 769 Jewish refugees, left the Romanian port of Constantsa hoping to reach Palestine. Towed into Istanbul harbour when its engines failed, it became the subject of diplomatic discussions between Britain and Turkey. Britain's chief concern was to discourage what it regarded as an undesirable traffic, and it proposed that the ship be returned to Romania. After ten weeks of wrangling the Struma was towed out to sea, its engines still disabled, where it was sunk by a Soviet submarine. There was one survivor.
Himmler ordered the closure of ghettos in Poland in mid-July 1942; most inhabitants were sent to extermination camps. Those Jews needed for war production would be confined in concentration camps. The deportations from the Warsaw Ghetto began on 22 July; over the almost two months of the Aktion, until 12 September, the population was reduced from 350,000 to 65,000. Those deported were transported in freight trains to the Treblinka extermination camp. Similar deportations happened in other ghettos, with many ghettos totally emptied. The first ghetto uprisings occurred in mid-1942 in small community ghettos. Although there were armed resistance attempts in both the larger and smaller ghettos in 1943, in every case they failed against the overwhelming German military force, and the remaining Jews were either killed or deported to the death camps.
Olga Lengyel, a prisoner at the Birkenau camp, wrote in her book entitled "Five Chimneys" that she had heard about Dr. Mengele from the other inmates before she saw him. Lengyel wrote that she had heard that Dr. Mengele was "good-looking" but she was surprised by how "really handsome" he was. Lengyel wrote, regarding Dr. Mengele: "Though he was making decisions that meant extermination, he was as pleasantly smug as any man could be."
The unstoppable Allied military advance continued and on July 24, 1944, Soviet troops liberated the first camp, Majdanek in eastern Poland, where over 360,000 had died. As the Soviet Army neared Auschwitz, Himmler ordered the complete destruction of the gas chambers. Throughout Hitler's crumbling Reich, the SS now began conducting death marches of surviving concentration camp inmates away from outlying areas, including some 66,000 from Auschwitz. Most of the inmates on these marches either dropped dead from exertion or were shot by the SS when they failed to keep up with the column.
The ideology of Nazism brought together elements of antisemitism, racial hygiene, and eugenics, and combined them with pan-Germanism and territorial expansionism with the goal of obtaining more Lebensraum (living space) for the Germanic people. Nazi Germany attempted to obtain this new territory by attacking Poland and the Soviet Union, intending to deport or kill the Jews and Slavs living there, who were considered by the Nazis to be inferior to the Aryan master race.