According to the Yad Vashem Holocaust Martyrs' and Heroes' Remembrance Authority in Jerusalem, "[a]ll the serious research" confirms that between five and six million Jews died.[391] Early postwar calculations were 4.2 to 4.5 million from Gerald Reitlinger;[392] 5.1 million from Raul Hilberg; and 5.95 million from Jacob Lestschinsky.[393] In 1986 Lucy S. Dawidowicz used the pre-war census figures to estimate 5.934 million.[394] Yehuda Bauer and Robert Rozett in the Encyclopedia of the Holocaust (1990) estimated 5.59–5.86 million.[395] A 1996 study led by Wolfgang Benz suggested 5.29 to 6.2 million, based on comparing pre- and post-war census records and surviving German documentation on deportations and killings.[391] Martin Gilbert arrived at a minimum of 5.75 million.[396] The figures include over one million children.[397]
Remarkably, there were instances of individual resistance and collective efforts at fighting back inside Auschwitz. Poles, Communists and other national groups established networks in the main camp. Some Jews assaulted Nazi guards, even at the entrance to the gas chambers. In October 1944, the Sonderkommando crew at crematoria IV revolted and destroyed the crematoria. It was never used again.

After attending a series of trade schools in Brno and marrying Emilie Pelzl in 1928, Schindler held a variety of jobs, including working in his father's farm machinery business in Svitavy, opening a driving school in Sumperk, and selling government property in Brno. He also served in the Czechoslovak army and in 1938 attained the rank of lance corporal in the reserves. Schindler began working with the Amt Auslands/Abwehr (Office of the Military Foreign Intelligence) of the German Armed Forces in 1936. In February 1939, five months after the German annexation of the Sudetenland, he joined the Nazi Party. An opportunist businessman with a taste for the finer things in life, he seemed an unlikely candidate to become a wartime rescuer. During World War II, Schindler would rescue more than 1,000 Jews from deportation to Auschwitz, Nazi Germany's largest camp complex.

Aware that as witnesses to the killings they would eventually be killed themselves, the Sonderkommandos of Birkenau Kommando III staged an uprising on 7 October 1944, following an announcement that some of them would be selected to be "transferred to another camp"—a common Nazi ruse for the murder of prisoners.[228][229] They attacked the SS guards with stones, axes, and makeshift hand grenades, which they also used to damage Crematorium IV and set it on fire. As the SS set up machine guns to attack the prisoners in Crematorium IV, the Sonderkommandos in Crematorium II also revolted, some of them managing to escape the compound.[229][230] The rebellion was suppressed by nightfall.[231]
Overy wrote that blitzkrieg as a "coherent military and economic concept has proven a difficult strategy to defend in light of the evidence".[127] Milward's theory was contrary to Hitler's and German planners' intentions. The Germans, aware of the errors of the First World War, rejected the concept of organising its economy to fight only a short war. Therefore, focus was given to the development of armament in depth for a long war, instead of armament in breadth for a short war. Hitler claimed that relying on surprise alone was "criminal" and that "we have to prepare for a long war along with surprise attack". During the winter of 1939–40, Hitler demobilised many troops from the army to return as skilled workers to factories because the war would be decided by production, not a quick "Panzer operation".[128]
On 1 August 1940, Governor-General Hans Frank issued a decree requiring all Kraków Jews to leave the city within two weeks. Only those who had jobs directly related to the German war effort would be allowed to stay. Of the 60,000 to 80,000 Jews then living in the city, only 15,000 remained by March 1941. These Jews were then forced to leave their traditional neighbourhood of Kazimierz and relocate to the walled Kraków Ghetto, established in the industrial Podgórze district.[41][42] Schindler's workers travelled on foot to and from the ghetto each day to their jobs at the factory.[43] Enlargements to the facility in the four years Schindler was in charge included the addition of an outpatient clinic, co-op, kitchen, and dining room for the workers, in addition to expansion of the factory and its related office space.[44]
Initially, Schindler was mostly interested in the money-making potential of the business and hired Jews because they were cheaper than Poles—the wages were set by the occupying Nazi regime.[38] Later he began shielding his workers without regard for cost.[39] The status of his factory as a business essential to the war effort became a decisive factor enabling him to help his Jewish workers. Whenever Schindlerjuden (Schindler Jews) were threatened with deportation, he claimed exemptions for them. He claimed wives, children, and even people with disabilities were necessary mechanics and metalworkers.[39] On one occasion, the Gestapo came to Schindler demanding that he hand over a family that possessed forged identity papers. "Three hours after they walked in," Schindler said, "two drunk Gestapo men reeled out of my office without their prisoners and without the incriminating documents they had demanded."[40]
By July 1944, Germany was losing the war; the SS began closing down the easternmost concentration camps and deporting the remaining prisoners westward. Many were killed in Auschwitz and the Gross-Rosen concentration camp. Schindler convinced SS-Hauptsturmführer Amon Göth, commandant of the nearby Kraków-Płaszów concentration camp, to allow him to move his factory to Brněnec in the Protectorate of Bohemia and Moravia, thus sparing his workers from almost certain death in the gas chambers. Using names provided by Jewish Ghetto Police officer Marcel Goldberg, Göth's secretary Mietek Pemper compiled and typed the list of 1,200 Jews who travelled to Brünnlitz in October 1944. Schindler continued to bribe SS officials to prevent the execution of his workers until the end of World War II in Europe in May 1945, by which time he had spent his entire fortune on bribes and black market purchases of supplies for his workers.