The first gassings at Auschwitz took place in early September 1941, when around 850 inmates—Soviet prisoners of war and sick Polish inmates—were killed with Zyklon B in the basement of block 11 in Auschwitz I. The building proved unsuitable, so gassings were conducted instead in crematorium I, also in at Auschwitz I, which operated until December 1942. There, more than 700 victims could be killed at once.[157] Tens of thousands were killed in crematorium I.[158] To keep the victims calm, they were told they were to undergo disinfection and de-lousing; they were ordered to undress outside, then were locked in the building and gassed. After its decommissioning as a gas chamber, the building was converted to a storage facility and later served as an SS air raid shelter.[159] The gas chamber and crematorium were reconstructed after the war. Dwork and van Pelt write that a chimney was recreated; four openings in the roof were installed to show where the Zyklon B had entered; and two of the three furnaces were rebuilt with the original components.[160]
In the final months of the war, SS guards moved camp inmates by train or on forced marches, often called “death marches,” in an attempt to prevent the Allied liberation of large numbers of prisoners. As Allied forces moved across Europe in a series of offensives against Germany, they began to encounter and liberate concentration camp prisoners, as well as prisoners en route by forced march from one camp to another. The marches continued until May 7, 1945, the day the German armed forces surrendered unconditionally to the Allies.
At the three Reinhard camps the victims were killed by the exhaust fumes of stationary diesel engines.[279] Gold fillings were pulled from the corpses before burial, but the women's hair was cut before death. At Treblinka, to calm the victims, the arrival platform was made to look like a train station, complete with fake clock.[300] Majdanek used Zyklon-B gas in its gas chambers.[301] In contrast to Auschwitz, the three Reinhard camps were quite small.[302] Most of the victims at these camps were buried in pits at first. Sobibór and Bełżec began exhuming and burning bodies in late 1942, to hide the evidence, as did Treblinka in March 1943. The bodies were burned in open fireplaces and the remaining bones crushed into powder.[303]
[t]hroughout the Polish Campaign, the employment of the mechanised units revealed the idea that they were intended solely to ease the advance and to support the activities of the infantry....Thus, any strategic exploitation of the armoured idea was still-born. The paralysis of command and the breakdown of morale were not made the ultimate aim of the ... German ground and air forces, and were only incidental by-products of the traditional maneuvers of rapid encirclement and of the supporting activities of the flying artillery of the Luftwaffe, both of which had as their purpose the physical destruction of the enemy troops. Such was the Vernichtungsgedanke of the Polish campaign.[82]
In early 1942, mass exterminations were moved to two provisional gas chambers (the "red house" and "white house", known as bunkers 1 and 2) in Auschwitz II, while the larger crematoria (II, III, IV, and V) were under construction. Bunker 2 was temporarily reactivated from May to November 1944, when large numbers of Hungarian Jews were gassed.[161] In summer 1944 the combined capacity of the crematoria and outdoor incineration pits was 20,000 bodies per day.[162] A planned sixth facility—crematorium VI—was never built.[163] Prisoners were transported from all over German-occupied Europe by rail, arriving in daily convoys.[164] By July 1942, the SS were conducting "selections". Incoming Jews were segregated; those deemed able to work were sent to the selection officer's right and admitted into the camp, and those deemed unfit for labor were sent to the left and immediately gassed.[165] The group selected to die, about three-quarters of the total,[c] included almost all children, women with small children, the elderly, and all those who appeared on brief and superficial inspection by an SS doctor not to be fit for work.[167]
In the last months of Hitler’s Reich, as the German armies retreated, the Nazis began marching the prisoners still alive in the concentration camps to the territory they still controlled. The Germans forced the starving and sick Jews to walk hundreds of miles. Most died or were shot along the way. About a quarter of a million Jews died on the death marches.
^ Some of the military historians who consider Operation Citadel, or at least the southern pincer, as envisioning a blitzkrieg attack or state it was intended as such are: Lloyd Clark (Clark 2012, p. 187), Roger Moorhouse (Moorhouse 2011, p. 342), Mary Kathryn Barbier (Barbier 2002, p. 10), David Glantz (; Glantz & House 2004, pp. 63, 78, 149, 269, 272, 280), Jonathan House (Glantz & House 2004, pp. 63, 78, 149, 269, 272, 280), Hedley Paul Willmott (Willmott 1990, p. 300), Oscar Pinkus (Pinkus 2005, p. 35) and others.
Similarly, in Ordinary Men (1992), Christopher Browning examined the deeds of German Reserve Police Battalion 101 of the Ordnungspolizei ("order police"), used to commit massacres and round-ups of Jews, as well as mass deportations to the death camps. The members of the battalion were middle-aged men of working-class background from Hamburg, who were too old for regular military duty. They were given no special training. During the murder of 1,500 Jews from Józefów in Poland, their commander allowed them to opt out of direct participation. Fewer than 12 men out of a battalion of 500 did so. Influenced by the Milgram experiment on obedience, Browning argued that the men killed out of peer pressure, not bloodlust.[471]
The first prisoners at Auschwitz included German prisoners transferred from Sachsenhausen concentration camp in Germany, where they had been incarcerated as repeat criminal offenders, and Polish political prisoners from Lodz via Dachau concentration camp and from Tarnow in Krakow District of the Generalgouvernement (that part of German-occupied Poland not annexed to Nazi Germany, linked administratively to German East Prussia, or incorporated into the German-occupied Soviet Union).

His tasks for the Abwehr included collecting information on railways, military installations, and troop movements, as well as recruiting other spies within Czechoslovakia, in advance of a planned invasion of the country by Nazi Germany.[9] He was arrested by the Czech government for espionage on 18 July 1938 and immediately imprisoned, but was released as a political prisoner under the terms of the Munich Agreement, the instrument under which the Czech Sudetenland was annexed into Germany on 1 October.[10][11] Schindler applied for membership in the Nazi Party on 1 November and was accepted the following year.[12]