At Auschwitz, after the chambers were filled, the doors were shut and pellets of Zyklon-B were dropped into the chambers through vents,[293] releasing toxic prussic acid, or hydrogen cyanide.[294] Those inside died within 20 minutes; the speed of death depended on how close the inmate was standing to a gas vent, according to the commandant Rudolf Höss, who estimated that about one-third of the victims died immediately.[295] Johann Kremer, an SS doctor who oversaw the gassings, testified that: "Shouting and screaming of the victims could be heard through the opening and it was clear that they fought for their lives."[296] The gas was then pumped out, the bodies were removed, gold fillings in their teeth were extracted, and women's hair was cut.[297] The work was done by the Sonderkommando, work groups of mostly Jewish prisoners.[298] At Auschwitz, the bodies were at first buried in deep pits and covered with lime, but between September and November 1942, on the orders of Himmler, they were dug up and burned. In early 1943, new gas chambers and crematoria were built to accommodate the numbers.[299]
After Germany invaded Poland in September 1939, sparking World War II, the Germans converted Auschwitz I from an army barracks to hold Polish political prisoners.[3] The first prisoners, German criminals brought to the camp as functionaries, arrived in May 1940,[4] and the first gassing of prisoners took place in block 11 of Auschwitz I in September 1941. Auschwitz II–Birkenau went on to become a major site of the Nazis' Final Solution to the Jewish Question. From early 1942 until late 1944, transport trains delivered Jews from all over German-occupied Europe to the camp's gas chambers. Of the estimated 1.3 million people sent to Auschwitz, at least 1.1 million died,[5] around 90 percent of them Jews.[6] Approximately one in six Jews killed in the Holocaust died at the camp.[7] Others deported to Auschwitz included 150,000 non-Jewish Poles, 23,000 Roma, 15,000 Soviet prisoners of war, 400 Jehovah's Witnesses, tens of thousands of others of diverse nationalities, and an unknown number of gay men. Many of those not killed in the gas chambers died because of starvation, forced labor, infectious diseases, individual executions, and medical experiments.
The Maginot Line: the Allies expected a protracted, defensive war  © Across the English Channel, a stunned British military establishment struggled to determine how it was that events had so quickly gone so horribly wrong. The BEF had sailed for France believing that they and their French ally were well equipped and well trained to fight a modern war. In truth, as events proved, they were completely unprepared to face Hitler's Wehrmacht.
When a train carrying Jewish prisoners arrived “selections” would be conducted on the railroad platform, or ramp. Newly arrived persons classified by the SS physicians as unfit for labor were sent to the gas chambers: these included the ill, the elderly, pregnant women and children. In most cases, 70-75% of each transport was sent to immediate death. These people were not entered in the camp records; that is, they received no serial numbers and were not registered, and this is why it is possible only to estimate the total number of victims.
Before the outbreak of war, Poland had been a relative haven for European Jews - Krakow's Jewish population numbered over 50,000. But when Germany invaded, destruction began immediately and it was merciless. Jews were herded into crowded ghettos, randomly beaten and humiliated, capriciously killed. Jewish property and businesses were summarily destroyed, or appropriated by the SS and 'sold' to Nazi 'investors', one of whom was the fast talking, womanizing, money hungry Schindler.
 In October 1944, after the SS transferred the Emalia Jews to Plaszow, Schindler sought and obtained authorization to relocate his plant to Brünnlitz (Brnenec) in Moravia, and reopen it exclusively as an armaments factory. One of his assistants drew several versions of a list of up to 1,200 Jewish prisoners needed to work in the new factory. These lists came to be known collectively as “Schindler's List.” Schindler met the specifications required by the SS to classify Brünnlitz as a subcamp of Gross-Rosen concentration camp and thereby facilitated the survival of around 800 Jewish men whom the SS deported from Plaszow via Gross-Rosen to Brünnlitz and between 300 and 400 Jewish women from Plaszow via Auschwitz.
Starting out with 45 employees, the company grew to more than 1,700 at its peak in 1944. Initially, Schindler hired Jewish workers because they were a less expensive Polish workforce. But as Nazi atrocities against the Jewish community increased, Schindler’s attitude changed. With the help of Stern, he found reasons to hire more Jewish workers, regardless of their abilities. By 1942, nearly half of his employees were Jewish and were known as Schindlerjuden (Schindler Jews). When the Nazis began to relocate Krakow’s Jews to labor camps, Itzhak Stern and several hundred other employees were among them. Schindler raced to the train station and confronted an SS officer, arguing that his workers were essential to the war effort. After several tense minutes of dropping names and making veiled threats, Schindler was able to free his workers and escort them back to the factory.

Historian Victor Davis Hanson states that Blitzkrieg "played on the myth of German technological superiority and industrial dominance," adding that German successes, particularly that of its Panzer divisions were "instead predicated on the poor preparation and morale of Germany's enemies."[119] Hanson also reports that at a Munich public address in November 1941, Hitler had "disowned" the concept of Blitzkrieg by calling it an "idiotic word."[120] Further, successful Blitzkrieg operations were predicated on superior numbers, air-support, and were only possible for short periods of time without sufficient supply lines.[121] For all intents and purposes, Blitzkrieg ended at the Eastern Front once the German forces gave up Stalingrad, after they faced hundreds of new T-34 tanks, when the Luftwaffe became unable to assure air dominance, and following the stalemate at Kursk—to this end, Hanson concludes that German military success was not accompanied by the adequate provisioning of its troops with food and materiel far from the source of supply, which contributed to its ultimate failures.[122] Despite its later disappointments as German troops extended their lines at too great a distance, the very specter or armored Blitzkrieg forces initially proved victorious against Polish, Dutch, Belgian, and French armies early in the war.[123]
Prisoners received half a liter of coffee substitute or a herbal "tea" in the morning, but no food.[109] A second gong heralded roll call, when inmates had to line up outside in rows of ten to be counted. No matter how cold the weather, prisoners had to wait for the SS to arrive for the count. How long they stood there depended on the officers' mood, and whether there had been escapes or other events attracting punishment.[110] Guards might force the prisoners to squat for an hour with their hands above their heads, or hand out beatings or detention for infractions such as having a missing button or an improperly cleaned food bowl. The inmates were counted and re-counted.[111]

After the war, Albert Speer claimed that the German economy achieved greater armaments output, not because of diversions of capacity from civilian to military industry but through streamlining of the economy. Richard Overy pointed out some 23 percent of German output was military by 1939. Between 1937 and 1939, 70 percent of investment capital went into the rubber, synthetic fuel, aircraft and shipbuilding industries. Hermann Göring had consistently stated that the task of the Four Year Plan was to rearm Germany for total war. Hitler's correspondence with his economists also reveals that his intent was to wage war in 1943–1945, when the resources of central Europe had been absorbed into the Third Reich.[132]
The British army took lessons from the successful infantry and artillery offensives on the Western Front in late 1918. To obtain the best co-operation between all arms, emphasis was placed on detailed planning, rigid control and adherence to orders. Mechanization of the army was considered a means to avoid mass casualties and indecisive nature of offensives, as part of a combined-arms theory of war.[35][36] The four editions of Field Service Regulations published after 1918 held that only combined-arms operations could create enough fire power to enable mobility on a battlefield. This theory of war also emphasized consolidation, recommending caution against overconfidence and ruthless exploitation.[37]
After the Allied landings at Normandy, Germany made attempts to overwhelm the landing force with armored attacks, but these failed for lack of co-ordination and Allied air superiority. The most notable attempt to use deep penetration operations in Normandy was at Mortain, which exacerbated the German position in the already-forming Falaise Pocket and assisted in the ultimate destruction of German forces in Normandy. The Mortain counter-attack was effectively destroyed by U.S. 12th Army Group with little effect on its own offensive operations.
Sometimes the mere presence of German troops in the vicinity was sufficient to spur a massacre. One example is what happened in the Polish village of Jedwabne, where neighbours murdered their Jewish neighbours. For years the massacre was blamed on the Germans, though many Poles likely knew that the local population had turned against its own Jews. In the Baltics, where the Germans were greeted as liberators by some segments of the population, the lure of political independence and the desire to erase any collaboration with the previous Soviet occupiers led nationalist bands to murder local Jews.
The Roma refer to the genocide of the Romani people as the Pořajmos.[414] Because they are traditionally a private people with a culture based on oral history, less is known about their experience than that of any other group.[415] Bauer writes that this can be attributed to the Roma's distrust and suspicion, and to their humiliation because some of the taboos in Romani culture regarding hygiene and sex were violated at Auschwitz.[416] In May 1942, the Roma were placed under similar laws to the Jews. On 16 December 1942, Himmler issued a decree that "Gypsy Mischlinge [mixed breeds], Roma Gypsies, and members of the clans of Balkan origins who are not of German blood" should be sent to Auschwitz, unless they had served in the Wehrmacht.[417] He adjusted the order on 15 November 1943; in the occupied Soviet areas, "sedentary Gypsies and part-Gypsies are to be treated as citizens of the country. Nomadic Gypsies and part-Gypsies are to be placed on the same level as Jews and placed in concentration camps."[418] Bauer argues that this adjustment reflected Nazi ideology that the Roma, originally an Aryan population, had been "spoiled" by non-Romani blood.[419]
British theorists J.F.C. Fuller and Captain B. H. Liddell Hart have often been associated with blitzkrieg's development, though this is a matter of controversy. The British War Office did permit an Experimental Mechanised Force, formed on 1 May 1927, that was wholly motorized including self propelled artillery and motorised engineers. It is argued that Guderian, a critical figure in blitzkrieg's conception, drew some of his inspiration from Liddell Hart. This was based on a paragraph in the English edition of Guderian's autobiography in which he credits Liddell Hart. In opposition, it is argued that Liddell Hart, as editor of the autobiography's English edition, wrote that paragraph himself or, more broadly, that his influence on Guderian was not as significant as held. Fuller's influence is less clear. During the war, he developed plans for massive, independent tank operations and was subsequently studied by the German leadership. It is variously argued that Fuller's wartime plans and post-war writings were an inspiration, or that his readership was low and German experiences during the war received more attention.
Guderian's leadership was supported, fostered and institutionalised by his supporters in the Reichswehr General Staff system, which worked the Army to greater and greater levels of capability through massive and systematic Movement Warfare war games in the 1930s. Guderian's book incorporated the work of theorists such as Ludwig Ritter von Eimannsberger, whose book, The Tank War (Der Kampfwagenkrieg) (1934) gained a wide audience in the German army. Another German theorist, Ernst Volckheim, wrote a huge amount on tank and combined arms tactics and was influential to German thinking on the use of armoured formations but his work was not acknowledged in Guderian's writings.[155]
Płaszów concentration camp opened in March 1943 on the former site of two Jewish cemeteries on Jerozilimska Street, about 2.5 kilometres (1.6 mi) from the DEF factory.[49] In charge of the camp was SS-Hauptsturmführer Amon Göth, a sadist who would shoot inmates of the camp at random.[48] Inmates at Płaszów lived in constant fear for their lives.[50] Emilie Schindler called Göth "the most despicable man I have ever met."[51]