German operational theories were revised after the First World War. The Treaty of Versailles limited the Reichswehr to a maximum of 100,000 men, making impossible the deployment of mass armies. The German General Staff was abolished by the treaty but continued covertly as the Truppenamt (Troop Office), disguised as an administrative body. Committees of veteran staff officers were formed within the Truppenamt to evaluate 57 issues of the war.[29] By the time of the Second World War, their reports had led to doctrinal and training publications, including H. Dv. 487, Führung und Gefecht der verbundenen Waffen (Command and Battle of the Combined Arms), known as das Fug (1921–23) and Truppenführung (1933–34), containing standard procedures for combined-arms warfare. The Reichswehr was influenced by its analysis of pre-war German military thought, in particular infiltration tactics, which at the end of the war had seen some breakthroughs on the Western Front and the manoeuvre warfare which dominated the Eastern Front.
Some prisoners kept diaries, recording life inside the camp, so that the world would one day know the story of what happened to them. Others collected evidence of the killings and events within the camp, burying it in the hope that one day someone would find the evidence of the atrocities. Prisoners had to be careful to make sure these form of indirect resistance went undiscovered by the SS guards and kapos.
When Germany invaded Poland in September 1939, it gained control of about 2 million Jews in the occupied territory. The rest of Poland was occupied by the Soviet Union, which had control of the rest of Poland's pre-war population of 3.3–3.5 million Jews.[141] German plans for Poland included expelling gentile Poles from large areas, confining Jews, and settling Germans on the emptied lands.[142] The Germans initiated a policy of sending Jews from all territories they had recently annexed (Austria, Czechoslovakia, and western Poland) to the central section of Poland, which they called the General Government. There, the Jews were concentrated in ghettos in major cities,[143] chosen for their railway lines to facilitate later deportation.[144] Food supplies were restricted, public hygiene was difficult, and the inhabitants were often subjected to forced labor.[145] In the work camps and ghettos, at least half a million Jews died of starvation, disease, and poor living conditions.[146] Jeremy Black writes that the ghettos were not intended, in 1939, as a step towards the extermination of the Jews. Instead, they were viewed as part of a policy of creating a territorial reservation to contain them.[147][l]

In Autumn 1943, the camp administration was reorganized following a corruption scandal. By the end of 1943, the prisoner population of Auschwitz main camp, Birkenau, Monowitz and other sub-camps was over 80,000: 18,437 in the main camp, 49,114 in Birkenau, and 13,288 at Monowitz where I G Farben had its synthetic rubber plant. Up to 50,000 prisoners were scattered around 51 sub-camps such as Rajsko, an experimental agricultural station, and Gleiwitz, a coal mine (see The List of the Camps for a complete list of those sub-camps).
During the era of the Holocaust, German authorities also targeted other groups because of their perceived racial and biological inferiority: Roma (Gypsies), people with disabilities, and some of the Slavic peoples (Poles, Russians, and others). Other groups were persecuted on political, ideological, and behavioral grounds, among them Communists, Socialists, Jehovah's Witnesses, and homosexuals.
As Soviet armies advanced in 1944 and early 1945, Auschwitz was gradually abandoned. On January 18, 1945, some 60,000 prisoners were marched to Wodzisław Śląski, where they were put on freight trains (many in open cars) and sent westward to concentration camps away from the front. One in four died en route from starvation, cold, exhaustion, and despair. Many were shot along the way in what became known as the “death marches.” The 7,650 sick or starving prisoners who remained were found by arriving Soviet troops on January 27, 1945.
From 1942 onwards, the camp became the site of one of the greatest mass murders in the history of humanity, committed against the European Jews as part of Hitler's plan for the complete destruction of that people (the Final Solution). An estimated 1.1 million people were killed or died at Auschwitz-Birkenau, the vast majority of whom were Jewish men, women and children deported from their homes all over occupied Europe. They were transported to Auschwitz-Birkenau in overcrowded cattle wagons, and upon arrival sent immediately to their deaths in the Birkenau gas chambers. Their bodies were afterwards cremated in industrial furnaces in the crematoria.
Subject to harsh conditions—including inadequate shelter and sanitation—given minimal food, and worked to exhaustion, those who could no longer work faced transport back to Birkenau for gassing. German corporations invested heavily in the slave-labour industries adjacent to Auschwitz. In 1942 IG Farben alone invested more than 700 million Reichsmarks in its facilities at Auschwitz III.
Germany’s plans to attack the USSR were heavily influenced by Adolf Hitler’s racist, anti-Semitic and anti-Bolshevik postulates, which he had largely formulated much earlier in his agenda-setting book Mein Kampf. Joseph Stalin failed to fully take into account the highly ideological nature of Hitler’s political and military-strategic thinking; this led to mistakes in interpreting the Third Reich’s plans vis-a-vis the Soviet Union.
In the final days of the war, just before the entry of the Russian army into Moravia, Schindler managed to smuggle himself back into Germany, into Allied-controlled territory. The wartime industrial tycoon was by now penniless. Jewish relief organizations and groups of survivors supported him modestly over the years, helping finance his (in the long run, unsuccessful) emigration to South America. When Schindler visited Israel in 1961, the first of seventeen visits, he was treated to an overwhelming welcome from 220 enthusiastic survivors.  He continued to live partly in Israel and partly in Germany. After his death in Hildesheim, Germany, in October 1974, the mournful survivors brought the remains of their rescuer to Israel to be laid to eternal rest in the Catholic Cemetery of Jerusalem. The inscription on his grave says: 'The unforgettable rescuer of 1,200 persecuted Jews".

The Germans conquered large areas of the Soviet Union but their failure to destroy the Red Army before the winter of 1941 was a strategic failure that made German tactical superiority and territorial gains irrelevant.[95] The Red Army had survived enormous losses and regrouped with new formations far to the rear of the front line. During the Battle of Moscow, the Red Army defeated the German Army Group Center and for the first time in the war seized the strategic initiative.[95][96]
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.
Here over an acre of ground lay dead and dying people. You could not see which was which. ... The living lay with their heads against the corpses and around them moved the awful, ghostly procession of emaciated, aimless people, with nothing to do and with no hope of life, unable to move out of your way, unable to look at the terrible sights around them ... Babies had been born here, tiny wizened things that could not live. ... A mother, driven mad, screamed at a British sentry to give her milk for her child, and thrust the tiny mite into his arms. ... He opened the bundle and found the baby had been dead for days. This day at Belsen was the most horrible of my life.

The Holocaust was the systematic annihilation of six million Jews by the Nazis during World War 2. In 1933 nine million Jews lived in the 21 countries of Europe that would be military occupied by Germany during the war. By 1945 two out of every three European Jews had been killed. 1.5 million children were murdered. This figure includes more than 1.2 million Jewish children, tens of thousands of Gypsy children and thousands of handicapped children.
Conventional wisdom traces blitzkrieg, “lightning war,” to the development in Germany between 1918 and 1939 of a body of doctrine using mobility to prevent repetition of the attritional deadlock of World War I. Soldiers such as Hans von Seeckt and Heinz Guderian allegedly perceived more clearly than their counterparts elsewhere in Europe the military potential of the internal-combustion engine combined with modern communications technology. Large formations moving on tracks and wheels, directed by radios, could rupture an enemy’s front and so disorganize its rear that countermeasures would be paralyzed. First tested in Poland, the concept reached perihelion in France and the Low Countries in 1940, when in less than six weeks the German army crushed the combined forces of four nations. Applied a year later against the Soviet Union, blitzkrieg purportedly brought the Wehrmacht to the gates of Moscow in six months. Some accounts insist that only Adolf Hitler’s incompetent interference tipped the war’s balance so far against Germany that even blitzkrieg’s most sophisticated refinements could do no more than stave off the Reich’s collapse.

On November 12, 1938, Field Marshal Hermann Göring convened a meeting of Nazi officials to discuss the damage to the German economy from pogroms. The Jewish community was fined one billion Reichsmarks. Moreover, Jews were made responsible for cleaning up the damage. German Jews, but not foreign Jews, were barred from collecting insurance. In addition, Jews were soon denied entry to theatres, forced to travel in separate compartments on trains, and excluded from German schools. These new restrictions were added to earlier prohibitions, such as those barring Jews from earning university degrees, from owning businesses, or from practicing law or medicine in the service of non-Jews. The Nazis would continue to confiscate Jewish property in a program called “Aryanization.” Göring concluded the November meeting with a note of irony: “I would not like to be a Jew in Germany!”

Hitler’s Wehrmacht suffered its first major defeat outside Moscow in December 1941. This put an end to the blitzkrieg as a phenomenon of that period of history. However, three and a half more years of bloody battles lay ahead as part of World War II, which saw the Soviet Union, the United States, the United Kingdom, China and France act as allies against a most dangerous common enemy.
^ The escapees included 396 Polish men and 10 Polish women; 164 men from the Soviet Union (including 50 prisoners of war), and 15 women; 112 Jewish men and three Jewish women; 36 Romani/Sinti men and two women; 22 German men and nine women; 19 Czech men and four women; two Austrians; one Yugoslav woman and one man; and 15 other men and one woman.[216]
Oskar Schindler (28 April 1908 – 9 October 1974) was a German industrialist and a member of the Nazi Party who is credited with saving the lives of 1,200 Jews during the Holocaust by employing them in his enamelware and ammunitions factories in occupied Poland and the Protectorate of Bohemia and Moravia. He is the subject of the 1982 novel Schindler's Ark and its 1993 film adaptation, Schindler's List, which reflected his life as an opportunist initially motivated by profit, who came to show extraordinary initiative, tenacity, courage, and dedication to save the lives of his Jewish employees.