The German view of the Roma as hereditary criminals and "asocials" was reflected in their classification in the concentration camps, where they were usually counted among the asocials and given black triangles to wear.[420] According to Niewyk and Nicosia, at least 130,000 died out of nearly one million in German-occupied Europe.[415] The United States Holocaust Memorial Museum calculates at least 220,000.[421] Ian Hancock, who specializes in Romani history and culture, argues for between 500,000 and 1,500,000.[422] The treatment of the Roma was not consistent across German-occupied territories. Those in France and the Low Countries were subject to restrictions on movement and some confinement to collection camps, while those in Central and Eastern Europe were sent to concentration camps and murdered by soldiers and execution squads.[423] Before being sent to the camps, the Roma were herded into ghettos, including several hundred into the Warsaw Ghetto.[219] Further east, teams of Einsatzgruppen tracked down Romani encampments and murdered the inhabitants on the spot, leaving no records of the victims.[423] After the Germans occupied Hungary, 1,000 Roma were deported to Auschwitz.[424][x]
On January 20, 1942, several top officials of the German government met to officially coordinate the military and civilian administrative branches of the Nazi system to organize a system of mass murder of the Jews. This meeting, called the Wannsee Conference, "marked the beinning of the full-scale, comprehensive extermination operation [of the Jews] and laid the foundations for its organization, which started immediately after the conference ended" (Yahil, The Holocaust, p. 318).
The twin pairs of gas chambers were numbered II and III, and IV and V. The first opened on March 31, 1943, the last on April 4, 1943. The total area of the gas chambers was 2,255 square meters; the capacity of these crematoria was 4,420 people. Those selected to die were undressed in the undressing room and then pushed into the gas chambers. It took about 20 minutes for all the people to death. In II and III, the killings took place in underground rooms, and the corpses were carried to the five ovens by an electrically operated lift. Before cremation gold teeth and any other valuables, such as rings, were removed from the corpses. In IV and V the gas chambers and ovens were on the same level, but the ovens were so poorly built and the usage was so great that they repeatedly malfunctioned and had to be abandoned. The corpses were finally burned outside, in the open, as in 1943. Jewish sonderkommandos worked the crematoria under SS supervision.
Blitzkrieg, as practiced by the Wehrmacht during World War II, was a tactical action executed with extreme competence. It involved the coordination of all forces and it had a very small margin of error. But this coordination that made it such a successful tactic is the main thing missed when Blitzkrieg is referenced in day-to-day conversations that focus only on the speed by which a certain position is secured. All the other items we discussed (initiative, focus and tempo) fall apart without this synchronization.
The Luftwaffe did end up with an air force consisting mainly of relatively short-range aircraft, but this does not prove that the German air force was solely interested in ’tactical’ bombing. It happened because the German aircraft industry lacked the experience to build a long-range bomber fleet quickly, and because Hitler was insistent on the very rapid creation of a numerically large force. It is also significant that Germany's position in the centre of Europe to a large extent obviated the need to make a clear distinction between bombers suitable only for ’tactical’ and those necessary for strategic purposes in the early stages of a likely future war.[141]
The Theresienstadt family camp, which existed between September 1943 and July 1944, served a different purpose. A group of around 5,000 Jews had arrived in Auschwitz in September 1943 from the Theresienstadt ghetto in Czechoslovakia. The families were allowed to stay together, their heads were not shaved, and they could wear their own clothes. Correspondence between Adolf Eichmann's office and the International Red Cross suggests that the Germans set up the camp to cast doubt on reports, in time for a planned Red Cross visit to Auschwitz, that mass murder was taking place in Auschwitz. A second group of 5,000 arrived from Theresienstadt in December 1943. On 7 March 1944, the first group was sent to the gas chamber at crematorium III; before they died, they were asked to send postcards to relatives, postdated to 25 March.[148] This was the largest massacre of Czechoslovak citizens in history. News of the liquidation reached the Czechoslovak government-in-exile, which initiated diplomatic manoeuvers to save the remaining Jews. After the Red Cross visited Theresienstadt in June 1944 and were persuaded by the SS that no deportations were taking place from there, about 3,500 Jews were removed from the family camp to other sections of Auschwitz. The remaining 6,500 were murdered in the gas chambers between 10 and 12 July 1944.[149][150]
Almost all Jews within areas occupied by the Germans were killed. There were 3,020,000 Jews in the Soviet Union in 1939, and the losses were 1–1.1 million.[400] Around one million Jews were killed by the Einsatzgruppen in the occupied Soviet territories.[401][402] Of Poland's 3.3 million Jews, about 90 percent were killed.[369] Many more died in the ghettos of Poland before they could be deported.[403] The death camps accounted for half the number of Jews killed; 80–90 percent of death-camp victims are estimated to have been Jews.[394] At Auschwitz-Birkenau the Jewish death toll was 1.1 million;[286][404] Treblinka 870,000–925,000;[405] Bełżec 434,000–600,000;[406][287] Chełmno 152,000–320,000;[407][288] Sobibór 170,000–250,000;[408][291] and Majdanek 79,000.[289]
Victims usually arrived at the camps by freight train.[278] Almost all arrivals at the Operation Reinhard camps of Treblinka, Sobibór, and Bełżec were sent directly to the gas chambers,[279] with individuals occasionally selected to replace dead workers.[280] At Auschwitz, camp officials usually subjected individuals to selections;[281] about 25%[282] of the new arrivals were selected to work.[281] Those selected for death at all camps were told to undress and hand their valuables to camp workers.[283] They were then herded naked into the gas chambers. To prevent panic, they were told the gas chambers were showers or delousing chambers.[284] The procedure at Chełmno was slightly different. Victims there were placed in a mobile gas van and asphyxiated, while being driven to prepared burial pits in the nearby forests. There the corpses were unloaded and buried.[285]
More than 40 sub-camps, exploiting the prisoners as slave laborers, were also founded, mainly as various sorts of German industrial plants and farms, between 1942 and 1944. The largest of them was called Buna (Monowitz, with ten thousand prisoners) and was opened by the camp administration in 1942 on the grounds of the Buna-Werke synthetic rubber and fuel plant, six kilometers from the Auschwitz camp. The factory was built during the war by the German IG Farbenindustrie cartel, and the SS supplied prisoner labor. On November 1943, the Buna sub-camp became the seat of the commandant of the third part of the camp, Auschwitz III, to which some other Auschwitz sub-camps were subordinated.
A German term for “lightning war,” blitzkrieg is a military tactic designed to create disorganization among enemy forces through the use of mobile forces and locally concentrated firepower. Its successful execution results in short military campaigns, which preserves human lives and limits the expenditure of artillery. German forces tried out the blitzkrieg in Poland in 1939 before successfully employing the tactic with invasions of Belgium, the Netherlands and France in 1940. The blitzkrieg was also used by German commander Erwin Rommel during the North African campaign of World War II, and adopted by U.S. General George Patton for his army’s European operations.
Inmates at Birkenau numbered around 100,000 at their peak. They were of many different nationalities, but the vast majority of those that entered the camp were unregistered Jews, many of whom were immediately sent to their deaths in the gas chambers. Women and children stood the least chance of survival, and many died even before arriving at Birkenau due to the appalling conditions of the railway journeys. The unloading platform, where the brisk selection process was conducted, remains. Apart from physically fit men (who often perished later from the rigours of the camp) it was often only an accident of birth that merited a possibility of survival. Large numbers of twins survived until liberation as they were objects of interest to the research of Dr. Josef Mengele - a man disliked even by his Nazi peers.
Auschwitz, perhaps the most notorious and lethal of the concentration camps, was actually three camps in one: a prison camp (Auschwitz I), an extermination camp (Auschwitz II–Birkenau), and a slave labour camp (Auschwitz III–Buna-Monowitz). Upon arrival, Jewish prisoners faced what was called a Selektion. A German doctor presided over the selection of pregnant women, young children, the elderly, handicapped, sick, and infirm for immediate death in the gas chambers. As necessary, the Germans selected able-bodied prisoners for forced labour in the factories adjacent to Auschwitz, where one German company, IG Farben, invested 700 million Reichsmarks in 1942 alone to take advantage of forced labour, a capital investment. The conglomerate presumed that slave labour would be a permanent part of the German economy. Deprived of adequate food, shelter, clothing, and medical care, these prisoners were literally worked to death. Periodically, they would face another Selektion. The Nazis would transfer those unable to work to the gas chambers of Birkenau.

Treatment inside the concentration camps were horrible. Prisoners were given tiny rations of food and forced into physical labor. They often slept more than three to a bed without pillows or blankets, even in the winter months. In many concentration camps, Nazi doctors conducted medical experiments on prisoners against their will, in many cases killing the prisoners in the process.
The Sturmabteilung (S.A., Storm Troopers), a grassroots organization, helped Hitler undermine the German democracy. The Gestapo (Geheime Staatspolizei, Secret State Police), a force recruited from professional police officers, was given complete freedom to arrest anyone after February 28. The Schutzstaffel (SS, Protection Squad) served as Hitler’s personal bodyguard and eventually controlled the concentration camps and the Gestapo. The Sicherheitsdienst des Reichsführers­SS (S.D., Security Service of the SS) functioned as the Nazis' intelligence service, uncovering enemies and keeping them under surveillance.
In March 1943, the Krakow ghetto was being liquidated, and all the remaining Jews were being moved to the forced-labor camp of Plaszow, outside Krakow.  Schindler prevailed upon SS-Haupsturmführer Amon Goeth, the brutal camp commandant and a personal drinking companion, to allow him to set up a special sub-camp for his own Jewish workers at the factory site in Zablocie. There he was better able to keep the Jews under relatively tolerable conditions, augmenting their below-subsistence diet with food bought on the black market with his own money. The factory compound was declared out of bounds for the SS guards who kept watch over the sub-camp.

Use of bunkers I and 2 stopped in spring 1943 when the new crematoria were built, although bunker 2 became operational again in May 1944 for the murder of the Hungarian Jews.[47] Crematorium II, which had been designed as a mortuary with morgues in the basement and ground-level incinerators, was converted by installing gas-tight doors, vents for the Zyklon B to be dropped into the chamber, and ventilation equipment to remove the gas thereafter.[48] It went into operation in March 1943. Crematorium III was built using the same design. Crematoria IV and V, designed from the start as gassing centers, were also constructed that spring. By June 1943, all four crematoria were operational. Most of the victims were killed using these four structures.[49]
Irena Adamowicz Gino Bartali Archbishop Damaskinos Odoardo Focherini Francis Foley Helen of Greece and Denmark Princess Alice of Battenberg Marianne Golz Jane Haining Feng-Shan Ho Wilm Hosenfeld Constantin Karadja Jan Karski Valdemar Langlet Carl Lutz Aristides de Sousa Mendes Tadeusz Pankiewicz Giorgio Perlasca Marion Pritchard Ángel Sanz Briz Oskar Schindler Anton Schmid Irena Sendler Klymentiy Sheptytsky Ona Šimaitė Henryk Sławik Tina Strobos Chiune Sugihara Casper ten Boom Corrie ten Boom Johan van Hulst Raimondo Viale Raoul Wallenberg Johan Hendrik Weidner Rudolf Weigl Jan Zwartendijk