In September 1939, Germany invaded Poland, starting World War II. Schindler left his wife and traveled to Krakow, hoping to profit from the impending war. Looking for business opportunities, he quickly became involved in the black market. By October, Schindler used his charm and doled out “gifts of gratitude” (contraband goods) to bribe high-ranking German officers. Wanting to expand his business interests, Schindler obtained a former Jewish enamelware factory to produce goods for the German military.

In September 1939, the German army occupied the western half of Poland. German police soon forced tens of thousands of Polish Jews from their homes and into ghettoes, giving their confiscated properties to ethnic Germans (non-Jews outside Germany who identified as German), Germans from the Reich or Polish gentiles. Surrounded by high walls and barbed wire, the Jewish ghettoes in Poland functioned like captive city-states, governed by Jewish Councils. In addition to widespread unemployment, poverty and hunger, overpopulation made the ghettoes breeding grounds for disease such as typhus.

Killing on a mass scale using gas chambers or gas vans was the main difference between the extermination and concentration camps.[269] From the end of 1941, the Germans built six extermination camps in occupied Poland: Auschwitz II-Birkenau, Majdanek, Chełmno, and the three Operation Reinhard camps at Belzec, Sobibor, and Treblinka II.[44][270] Maly Trostenets, a concentration camp in the Reichskommissariat Ostland, became a killing centre in 1942.[44] Gerlach writes that over three million Jews were murdered in 1942, the year that "marked the peak" of the mass murder of Jews.[271] At least 1.4 million of these were in the General Government area of Poland.[272]

 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.
The next blow came a month later. In the early morning darkness of May 10, the Germans unleashed their Blitzkrieg against the Netherlands and Belgium. The attack sent the defending troops reeling. The roads overflowed with refugees fleeing the front. French and British troops rushing to the rescue were caught in the headlong retreat and pushed back. German dive-bombers - the Stukas - filled the sky, strafing the retreating mix of civilians and soldiers with machine gun and bomb. The Allies fought valiantly but in vain - the German war machine advanced unperturbed. In England, the invasion forced Prime Minister Neville Chamberlain to resign, to be replaced by Winston Churchill.
Soviet civilian populations in the occupied areas were heavily persecuted.[438] Villages throughout the Soviet Union were destroyed by German troops.[439] Germans rounded up civilians for forced labor in Germany and caused famine by taking foodstuffs.[440] In Belarus, Germany imposed a regime that deported some 380,000 people for slave labor and killed hundreds of thousands of civilians. Over 600 villages had their entire populations killed, and at least 5,295 Belarusian settlements were destroyed by the Germans. According to Timothy Snyder, of "the nine million people who were in the territory of Soviet Belarus in 1941, some 1.6 million were killed by the Germans in actions away from battlefields, including about 700,000 prisoners of war, 500,000 Jews, and 320,000 people counted as partisans (the vast majority of whom were unarmed civilians)".[441] The United States Holocaust Memorial Museum has estimated that 3.3 million of 5.7 million Soviet POWs died in German custody.[442] The death rates decreased as the POWs were needed to help the German war effort; by 1943, half a million had been deployed as slave labor.[409]

When the Nazi’s rose to power they built facilities to hold and, eventually kill, their enemies. When the first concentration camps were built in 1933, this primarily meant political dissidents and opponents of the Nazi government, such as German Communists, Socialists, Social Democrats but would grow to include asocial groups – Gypsies, Jehovah’s Witnesses, the homeless, the mentally ill and homosexuals.  It was not until Kristallnacht that the prisoners became primarily Jewish.

The origins of blitzkrieg are in some doubt: if it existed, who contributed to it, whether it was part of German war strategy from 1933–1939. There has been a great deal of debate about whether it existed as a coherent military strategy. Many historians[who?] now think that blitzkrieg was not a military theory and the campaigns conducted by the Germans from 1939 to circa 1942 (with the exception of Operation Barbarossa) were improvised, rather than being based on a particular military strategy. Blitzkrieg had been called a Revolution in Military Affairs (RMA) but many writers and historians have concluded that the Germans did not invent a new form of warfare but applied new technologies to traditional ideas of Bewegungskrieg (manoeuvre warfare) to achieve decisive victory.[109]
Rather than repeating the World War One Schlieffen Plan, the Germans in 1940 advanced with their main thrust through the Ardennes Forest, in order to smash the vulnerable flank of the Allies. As 29 German divisions advanced through the Netherlands and Belgium in the north, 45 further divisions, including about 2,400 tanks in 7 divisions, burst through the Allied right flank and drove towards the English Channel.
In 1914, German strategic thinking derived from the writings of Carl von Clausewitz (June 1, 1780 – November 16, 1831), Helmuth von Moltke the Elder (26 October 1800 – 24 April 1891) and Alfred von Schlieffen (28 February 1833 – 4 January 1913), who advocated manoeuvre, mass and envelopment to create the conditions for a decisive battle (Vernichtungsschlacht). During the war, officers such as Willy Rohr developed tactics to restore manoeuvre on the battlefield. Specialist light infantry (Sturmtruppen, "storm troops") were to exploit weak spots to make gaps for larger infantry units to advance with heavier weapons and exploit the success, leaving isolated strong points to troops following up. Infiltration tactics were combined with short hurricane artillery bombardments using massed artillery, devised by Colonel Georg Bruchmüller. Attacks relied on speed and surprise rather than on weight of numbers. These tactics met with great success in Operation Michael, the spring offensive of 1918 and restored temporarily the war of movement, once the Allied trench system had been overrun. The German armies pushed on towards Amiens and then Paris, coming within 120 kilometres (75 mi) before supply deficiencies and Allied reinforcements halted the advance.[27] Historian James Corum criticised the German leadership for failing to understand the technical advances of the First World War, having given tank production the lowest priority and having conducted no studies of the machine gun prior to that war.[28]
On the Eastern Front, the war did not bog down into trench warfare; German and Russian armies fought a war of manoeuvre over thousands of miles, which gave the German leadership unique experience not available to the trench-bound western Allies.[30] Studies of operations in the east led to the conclusion that small and coordinated forces possessed more combat power than large, uncoordinated forces. After the war, the Reichswehr expanded and improved infiltration tactics. The commander in chief, Hans von Seeckt, argued that there had been an excessive focus on encirclement and emphasized speed instead.[31] Seeckt inspired a revision of Bewegungskrieg (maneuver warfare) thinking and its associated Auftragstaktik, in which the commander expressed his goals to subordinates and gave them discretion in how to achieve them; the governing principle was "the higher the authority, the more general the orders were", so it was the responsibility of the lower echelons to fill in the details.[32] Implementation of higher orders remained within limits determined by the training doctrine of an elite officer-corps.[33] Delegation of authority to local commanders increased the tempo of operations, which had great influence on the success of German armies in the early war period. Seeckt, who believed in the Prussian tradition of mobility, developed the German army into a mobile force, advocating technical advances that would lead to a qualitative improvement of its forces and better coordination between motorized infantry, tanks, and planes.[34]
In October 1944, the 'Sonderkommando' crew crematoria IV revolted and destroyed the crematories. In November Himmler ordered gassings to stop, and a 'cleanup' operation was inaugurated to conceal traces of the mass murder. In January 1945, the Germans evacuated 58,000 prisoners who could walk. They left behind in the main camp, Birkenau and in Monowitz about 7,000 sick or incapacitated who they did not expect would live for long.
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]
Schindler's ties with the Abwehr and his connections in the Wehrmacht and its Armaments Inspectorate enabled him to obtain contracts to produce enamel cookware for the military.[31] These connections also later helped him protect his Jewish workers from deportation and death.[32] As time went on, Schindler had to give Nazi officials ever larger bribes and gifts of luxury items obtainable only on the black market to keep his workers safe.[33] Bankier, a key black market connection, obtained goods for bribes as well as extra materials for use in the factory.[34] Schindler himself enjoyed a lavish lifestyle and pursued extramarital relationships with his secretary, Viktoria Klonowska, and Eva Kisch Scheuer, a merchant specialising in enamelware from DEF.[35] Emilie Schindler visited for a few months in 1940 and moved to Kraków to live with Oskar in 1941.[36][37]