Historians differ on the date of the decision to murder Jews systematically, the so-called “final solution to the Jewish question.” There is debate about whether there was one central decision or a series of regional decisions in response to local conditions. In either case, when Germany attacked the Soviet Union, its former ally, in June of 1941, the Nazis began the systematic killing of Jews.
In 1942, with the Nazis occupying Holland, a thirteen-year-old Jewish girl and her family fled their home in Amsterdam and went into hiding. For the next two years, until their whereabouts were betrayed to the Gestapo, the Franks and another family lived cloistered in the “Secret Annexe” of an old office building. Cut off from the outside world, they faced hunger, boredom, the constant cruelties of living in confined quarters, and the ever-present threat of discovery and death. In her diary Anne Frank recorded vivid impressions of her experiences during this period. By turns thoughtful, moving, and surprisingly humorous, her account offers a fascinating commentary on human courage and frailty and a compelling self-portrait of a sensitive and spirited young woman whose promise was tragically cut short.
The Nazis then combined their racial theories with the evolutionary theories of Charles Darwin to justify their treatment of the Jews. The Germans, as the strongest and fittest, were destined to rule, while the weak and racially adulterated Jews were doomed to extinction. Hitler began to restrict the Jews with legislation and terror, which entailed burning books written by Jews, removing Jews from their professions and public schools, confiscating their businesses and property and excluding them from public events. The most infamous of the anti-Jewish legislation were the Nuremberg Laws, enacted on September 15, 1935. They formed the legal basis for the Jews' exclusion from German society and the progressively restrictive Jewish policies of the Germans.

Its historical significance makes the term Final Solution the most important example of the ability of Nazi language to integrate potentially different if not divergent approaches towards the so-called Jewish question into a conceptual frame of reference that helped facilitate systematic mass murder and to hide the Third Reich's genocidal policies behind technocratic abstractions, thus providing legitimization for perpetrators and enabling bystanders to claim not to know what was going on. Despite its inherent problems, most notably in evoking the illusion of coordinated planning and systematic implementation, the term Final Solution remains crucial for recognizing the process character of the Holocaust as a key element in a broader history of state-sponsored mass murder during the Nazi era.

He was capable of being so kind to the children, to have them become fond of him, to bring them sugar, to think of small details in their daily lives, and to do things we would genuinely admire ... And then, next to that, ... the crematoria smoke, and these children, tomorrow or in a half-hour, he is going to send them there. Well, that is where the anomaly lay.[48]
Walking the grounds of the memorial site, I arrived with Freund at the lip of the pit that had housed the bunker where Zeidel and the other members of the Burning Brigade had lived. The circumference was tremendous, nearly 200 feet in total. On its grassy floor, the Vilna Gaon Museum had erected a model of a double-sided ramp that the Burning Brigade had used to drop bodies onto the pyres.
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."

In 1942, Auschwitz II (Birkenau), originally intended to house slave laborers, began to be used instead as a combined labor camp and extermination camp.[23][24] Prisoners were transported there by rail from all over German-occupied Europe, arriving in daily convoys.[25] By July 1942, SS doctors were conducting "selections" where incoming Jews were segregated, and those considered able to work were admitted into the camp while those deemed unfit for labor were immediately killed in the gas chambers.[26] The arrivals that were selected to die, about three-quarters of the total,[a] included almost all children, women with small children, pregnant women, all the elderly, and all of those who appeared (in a brief and superficial inspection by an SS doctor) to be not completely fit and healthy.[28][29]