Reichsführer-SS Heinrich Himmler visited Auschwitz-Birkenau on July 17 and 18, 1942 and watched the gassing of 449 women and children in Bunker No. 1, according to his biographer Peter Padfield. On July 23, 1942, Himmler ordered the quarantine of the Birkenau camp because of a typhus epidemic, but the gassing of the Jews continued. On December 28, 1942, Himmler issued an order that the death rate "must be reduced at all costs" according to document 2172-PS that was introduced at the Nuremberg IMT. He meant the death rate from typhus; the gassing of the Jews did not stop.
Once Germany took over Poland in 1939, it created forced-labor camps. Thousands of prisoners died from working conditions, exhaustion, and starvation. After the outbreak of World War II, the number of concentration camps increased exponentially. The number of prisoners of war camps also rose, but after the first years of the war most were converted into concentration camps. Nazis forcibly relocated Jews from ghettos to concentration camps.
At Auschwitz, a large new camp was already under construction to be known as Auschwitz II (Birkenau). This would become the future site of four large gas chambers to be used for mass extermination. The idea of using gas chambers originated during the Euthanasia Program, the so-called "mercy killing" of sick and disabled persons in Germany and Austria by Nazi doctors.
Hitler believed that before monotheism and the Jewish ethical vision came along, the world operated according to the laws of nature and evolution: survival of the fittest. The strong survived and the weak perished. When the lion hunts the herd the young, the sick and weak are always the first victims. Nature is brutal but nature is balanced. There is no mercy. So too in antiquity-the great empires-the Babylonians, Greeks and Romans conquered, subjugated and destroyed other peoples. They respected no borders and showed no mercy. This too Hitler viewed as natural and correct. But in a world operating according to a Divinely-dictated ethical system—where a God-given standard applies and not anyone’s might—the weak did not need to fear the strong. As Hitler saw it, the strong were emasculated-this was neither normal nor natural and in Hitler’s eyes, the Jews were to blame.
The survey of her manuscripts compared an unabridged transcription of Anne Frank's original notebooks with the entries she expanded and clarified on loose paper in a rewritten form and the final edit as it was prepared for the English translation. The investigation revealed that all of the entries in the published version were accurate transcriptions of manuscript entries in Anne Frank's handwriting, and that they represented approximately a third of the material collected for the initial publication. The magnitude of edits to the text is comparable to other historical diaries such as those of Katherine Mansfield, Anaïs Nin and Leo Tolstoy in that the authors revised their diaries after the initial draft, and the material was posthumously edited into a publishable manuscript by their respective executors, only to be superseded in later decades by unexpurgated editions prepared by scholars.[57]
The Germans invaded the Netherlands, Luxembourg, Belgium, and France in May 1940. In the Netherlands, the Germans installed Arthur Seyss-Inquart as Reichskommissar, who quickly began to persecute the approximately 140,000 Dutch Jews. Jews were forced out of their jobs and had to register with the government. Non-Jewish Dutch citizens protested these measures, and in February 1941 they staged a strike that was quickly crushed.[161] After Belgium's surrender at the end of May 1940, it was ruled by a German military governor, Alexander von Falkenhausen, who enacted anti-Jewish measures against the country's 90,000 Jews, many of whom were refugees from Germany or Eastern Europe.[162]
The Holocaust was the systematic, bureaucratic, state-sponsored persecution and murder of six million Jews by the Nazi regime and its collaborators. Holocaust is a word of Greek origin meaning "sacrifice by fire." The Nazis, who came to power in Germany in January 1933, believed that Germans were "racially superior" and that the Jews, deemed "inferior," were an alien threat to the so-called German racial community.

In 1935, Mengele earned a PhD in anthropology from the University of Munich.[7] In January 1937, he joined the Institute for Hereditary Biology and Racial Hygiene in Frankfurt, where he worked for Dr. Otmar Freiherr von Verschuer, a German geneticist with a particular interest in researching twins.[7] As von Verschuer's assistant, Mengele focused on the genetic factors that result in a cleft lip and palate, or a cleft chin.[10] His thesis on the subject earned him a cum laude doctorate in medicine (MD) from the University of Frankfurt in 1938.[11] (Both of his degrees were revoked by the issuing universities in the 1960s.)[12] In a letter of recommendation, von Verschuer praised Mengele's reliability and his ability to verbally present complex material in a clear manner.[13] The American author Robert Jay Lifton notes that Mengele's published works were in keeping with the scientific mainstream of the time, and would probably have been viewed as valid scientific efforts even outside Nazi Germany.[13]