The murders were carried out primarily through mass shootings and poison gas in extermination camps, chiefly Auschwitz-Birkenau, Treblinka, Belzec, Sobibor, and Chełmno in occupied Poland.

Meant to force all German Jews to emigrate, regardless of means, the regime passed anti-Jewish laws, encouraged harassment, and orchestrated a nationwide pogrom in November 1938.

[19][20] The turn of the twentieth century saw a major effort to establish a German colonial empire overseas, leading to the Herero and Nama genocide and subsequent racial apartheid regime in South West Africa.

[25][31] The Nazi Party and its leader, Adolf Hitler, were also obsessed with reversing Germany's territorial losses and acquiring additional Lebensraum (living space) in Eastern Europe for colonization.

[44] The Nazi regime cracked down on crime and social outsiders—such as Roma and Sinti, homosexual men, and those perceived as workshy—through a variety of measures, including imprisonment in concentration camps.

[83] The war provided cover for "Aktion T4", the murder of around 70,000 institutionalized Germans with mental or physical disabilities at specialized killing centers using poison gas.

[104] Deportations stopped in early 1940 due to the opposition of Hans Frank, the leader of the General Governorate, who did not want his fiefdom to become a dumping ground for unwanted Jews.

[127][128] A quick victory was expected[129] and was planned to be followed by a massive demographic engineering project to remove 31 million people and replace them with German settlers.

[130] To increase the speed of conquest the Germans planned to feed their army by looting, exporting additional food to Germany, and to terrorize the local inhabitants with preventative killings.

[161] In July and August Heinrich Himmler, the leader of the SS (Schutzstaffel), made several visits to the death squads' zones of operation, relaying orders to kill more Jews.

[186] After the expansion of killings to target the entire Soviet Jewish population, the 3,000 men of the Einsatzgruppen proved insufficient and Himmler mobilized 21 battalions of Order Police to assist them.

[203] The first extermination camp was Chełmno in the Wartheland, established on the initiative of the local civil administrator Arthur Greiser with Himmler's approval; it began operations in December 1941 using gas vans.

[204][205][206] In October 1941, Higher SS and Police Leader of Lublin Odilo Globocnik[207] began work planning Belzec—the first purpose-built extermination camp to feature stationary gas chambers using carbon monoxide based on the previous Aktion T4 programme[208][209]—amid increasing talk among German administrators in Poland of large-scale murder of Jews in the General Governorate.

[210][204] In late 1941 in East Upper Silesia, Jews in forced-labor camps operated by the Schmelt Organization deemed "unfit for work" began to be sent in groups to Auschwitz where they were murdered.

[221] At other extermination camps, nearly everyone on a transport was killed on arrival, but at Auschwitz around 20–25 percent were separated out for labor,[222] although many of these prisoners died later on[223] through starvation, mass shooting, torture,[224] and medical experiments.

[238][239] By mid-1942, Nazi leaders decided to allow only 300,000 Jews to survive in the General Governorate by the end of the year for forced labor;[237] for the most part, only those working in armaments production were spared.

Si Kaddour Benghabrit and Abdelkader Mesli saved hundreds of Jews by hiding them in the basements of the Grand Mosque of Paris and other resistance efforts in France.

[269][270][271] The Independent State of Croatia had already shot or killed in concentration camps the majority of its Jewish population (along with a larger number of Serbs),[272][273] and later deported several thousand Jews in 1942 and 1943.

[287][288][289] German SS, police, and regular army units rarely had trouble finding enough men to shoot Jewish civilians, even though punishment for refusal was absent or light.

[290][291] Non-German perpetrators and collaborators included Dutch, French, and Polish policemen, Romanian soldiers, foreign SS and police auxiliaries, Ukrainian Insurgent Army partisans, and some civilians.

[311][312] Although conditions varied widely between camps, Jewish forced laborers were typically treated worse than non-Jewish prisoners and suffered much higher mortality rates.

[347][348][349] Rescuers' motivations varied on a spectrum from altruism to expecting sex or material gain; it was not uncommon for helpers to betray or murder Jews if their money ran out.

[359] On 26 June 1942, BBC services in all languages publicized a report by the Jewish Social-Democratic Bund and other resistance groups and transmitted by the Polish government-in-exile, documenting the killing of 700,000 Jews in Poland.

This money was spent aiding emigrants and providing direct relief in the form of parcels and other assistance to Jews living under German occupation, and after the war to Holocaust survivors.

[336] At this time, most concentration camp prisoners were Soviet and Polish civilians, either arrested for real or supposed resistance or for attempting to escape forced labor.

Around 1.47 million Jews were murdered in just 100 days from late July to early November 1942, a rate approximately 83% higher than the commonly suggested figure for the Rwandan genocide.

Limited success in finding relatives, the refusal of many non-Jews to return property,[418] and violent attacks such as the Kielce pogrom convinced many survivors to leave eastern Europe.

[395] During and after World War II, many European countries launched widespread purges of real and perceived collaborators that affected possibly as much as 2–3 percent of the population of Europe, although most of the resulting trials did not emphasize crimes against Jews.

Instead of convicting Eichmann on the basis of documentary evidence, Israeli prosecutors asked many Holocaust survivors to testify, a strategy that increased publicity but has proven controversial.

[473][474][475] Scholar Omer Bartov points out how the Holocaust was unique in that it was "the industrial killing of millions of human beings in factories of death, ordered by a modern state, organized by a conscientious bureaucracy, and supported by a law-abiding, patriotic 'civilized' society.