Section: How and why did the Holocaust happen?

How did the Holocaust happen?

The Holocaust took place in the context of the Second World War, which was started by the invasion of Poland in September 1939.  Here, German soldiers hoist the Nazi Flag over Krakow castle in 1939.

The Holocaust took place in the context of the Second World War, which was started by the invasion of Poland in September 1939.  Here, German soldiers hoist the Nazi Flag over Krakow castle in 1939.

Courtesy of The Wiener Holocaust Library Collections.

Prior to the start of the Second World War, Jews, Roma and those viewed as ‘ a-social ’ by the Nazis faced escalating persecution in Germany and its recently incorporated territories.

More than four hundred antisemitic laws were enacted by the Nazis between 1933 and 1938. In November 1938, the situation worsened, as hundreds of Jews were tortured and arrested and thousands of businesses were destroyed in a targeted pogrom known as Kristallnacht .

The persecution of Jews intensified as the Nazis invaded Poland on 1 September 1939 at the start of the Second World War.

This section will explore the main events of the Holocaust in chronological order.

Escalating persecution and ghettos, 1939

On 1 September 1939, Germany invaded Poland. In September 1939, Poland was home to over three million Jews. Prior to the invasion, the Nazis had not drawn up a specific or comprehensive plan for what to do with the Jewish population once Poland was occupied. The resulting policy of ghettoisation was improvised as a temporary solution.

In just a few months, millions of Jews were quickly imprisoned inside ghettos in Poland. Conditions inside ghettos were abysmal, and thousands quickly died from starvation, disease, and poor sanitation.

Forced ghettoisation was a large escalation from the pre-war anti-Jewish policy in Germany. Prior to the war, the Nazis had focused on encouraging Jews to emigrate from the Greater German Reich through their antisemitic policies and actions. By 1939 in Poland, the Nazis escalated their actions, and segregated and imprisoned Jews for future deportation. At this stage, the Nazis planned to deport Jews to Madagascar or lands further east. Later, in 1941, as both of these options were realised to be infeasible, the Nazis created extermination camps to liquidate the populations of the ghettos instead.

Creation of the Einsatzgruppen, 1939-41

The Einsatzgruppen  were mobile killing squads that were a part of the SS . Members were chosen for their fanatical belief in Nazi ideology and absolute commitment to Hitler.

The Einsatzgruppen were created by Reinhard Heydrich in 1939 to liquidate the Polish Intelligentsia and prevent them from coordinating a response to the German invasion of Poland. This was called Operation Tannenberg . The Einsatzgruppen were brutally efficient in their task.

When the Nazis began to plan for the invasion of the Soviet Union in 1941, the Einsatzgruppen were actively factored into the plans. Members of the Einsatzgruppen were informed that their role in the operation was to put down resistance behind enemy lines. Several types of enemies were specifically named by Himmler to be targeted: middle and high ranking communists, Jews in service of party or government and other ‘extremist’ elements. The Einsatzgruppen were also instructed to secretly encourage antisemitic or anticommunist pogroms .


General Keitel’s order

The Einsatzgruppen’s power increased in advance of the invasion of the Soviet Union.

On 13 March 1941, General Wilhelm Keitel signed a directive which stated that Himmler had been entrusted with ‘special tasks’ and gave him (and, therefore, the Einsatzgruppen) the authority to ‘act independently and on his own his own responsibility’ within the context of these tasks.

This order was an attempt to resolve previous issues of friction between the German Army and the SS in Poland and allow the Einsatzgruppen to combat what the Nazis saw as the ‘Jewish Bolshevik’ threat in the Soviet Union.

The Nazis associated Soviet communism, their ideological enemy, with Jews, their so-called racial enemy. They also regarded most Soviet citizens as racially inferior, even if they were not Jewish.

This order increased the power of the Einsatzgruppen and, in turn, their ability to carry out tasks independently. However, the Einsatzgruppen still worked closely with the German Army.

General Keitel’s order

A portrait of Wilhelm Keitel, courtesy of The Wiener Holocaust Library Collections.


Einsatzgruppen preparation for the invasion of the Soviet Union, 1941

The Einsatzgruppen’s main training for the invasion of the Soviet Union took place in the spring of 1941 at a police training academy at Pretzsch, fifty miles southwest of Berlin. The course took just three weeks and involved lectures on Nazi racial theory and basic military training.

In order to avoid soldiers being prosecuted under military law (as had happened previously in Poland), and to encourage complete ruthlessness when dealing with the enemy, military personnel were given legal immunity prior to the invasion of the Soviet Union. This action cleared the way for further escalation and more intense persecution of those deemed to be enemies.

Before the invasion began, the Einsatzgruppen were split into four groups (A, B, C and D). Each group covered a different territory, following behind the German Army’s invasion lines.

'Death by bullets' The Einsatzgruppen and the Soviet Union, 1941-1945

Initial invasion

The Nazis regarded Soviet citizens as racially and ideologically inferior, partly due to the Soviet Union’s communist system of rule (which the Nazis saw as the ideological enemy of fascism . The Nazis viewed communists and Jews as key enemies, who needed to be detained and eliminated in order to allow the Nazis to win the war and ensure the survival of the ‘ Aryan ’ race. In many Nazis’ minds, Jews and communists were inseparable.

The mass executions of those deemed to be enemies started almost instantly after the invasion. An indication of this violence can be seen in the actions of Einsatzkommando 9, a sub unit of Einsatzgruppe B, who, following the occupation of Vilnius on 30 June 1941, shot 500 Jews a day.


The Einsatzgruppen did not act alone. In many cases the German Army or local collaborators participated in the murders, either actively (in the shootings), by identifying Jews or other enemies, or by assisting in security roles, such as guards for camps.  One example of this collaboration can be seen shortly after the invasion in the first week of July 1941, where 5000 Jews in the cities of Riga and Daugavpils were detained and murdered by ethnic Germans and the Lithuanian Activist Front .

Further escalation

By late July 1941, the German Army’s advance on the eastern front had slowed and there were significant food and military shortages in Germany. This resulted in a low morale on the German home front. The Nazis blamed Jews for these shortages and this lack of military success in the Soviet Union, and suggested that Jews were not only sabotaging the war efforts through partisan activity, but were also unnecessarily draining the food supply.

Amid these growing problems on the home front, Himmler paid a series of visits to the Einsatzgruppen units across the Soviet Union in mid-August 1941. During these visits, Himmler orally issued instructions which encouraged the complete annihilation of Jews, regardless of age, gender or a proven connection to communism. After each visit, murders of Jews in that area quickly escalated.

Himmler’s visits further encouraged the widespread mass murder of Jews across the Soviet Union. There were few restrictions on the actions of the Einsatzgruppen, and they accordingly acted with little restraint or uniformity. In many areas, whole Jewish communities were swiftly murdered. In others, some were placed in ghettos. In others, some were spared, although in most cases this was only a temporary measure.

Deportation of German Jews, September 1941

In the autumn of 1941, approximately 338,000 Jews remained in Greater Germany. Until this point, Hitler had been reluctant to deport Jews in the German Reich until the war was over because of a fear of resistance and retaliation from the German population. But, in the autumn of 1941, key Nazi figures contributed to mounting pressure on Hitler to deport the German Jews. This pressure culminated in Hitler ordering the deportation of all Jews still in the Greater German Reich and Protectorate between 15-17 September 1941.

Following the order, Himmler, Heydrich and Eichmann attempted to find space for the Jews from the Greater German Reich in the already severely overcrowded ghettos in eastern Europe. Officials in the Łódź, Litzmannstadt, Minsk and Riga ghettos were all informed that they would need to absorb the population of Jews from the Greater German Reich, irrespective of overcrowding.

The Minsk Ghetto was full, so in order to make room for the Reich Jews, the local SD , German Army and local collaborators gathered approximately 25,000 of the local ghetto inhabitants, drove them to a local ravine, and murdered them. German Jews soon filled their places in the ghetto. Similar murders took place in Riga.

In Łódź Ghetto, no local Jews were removed prior to the arrival of 20,000 Jews from the Greater German Reich. Instead, following the success of the experiments in using gas vans for mass murder at Chełmno extermination camp in December 1941, deportations from the ghetto to Chełmno began on 16 January 1942, four days before the Wannsee Conference.

As with most of the Nazis’ murderous actions, the deportation of German Jews was improvised and haphazard . The increased numbers of Jews arriving in the ghettos of eastern Europe led to severe overcrowding, unsustainable food shortages and poor sanitation. This, in combination with the slow progress in the German invasion of the Soviet Union, convinced the Nazis that a ‘solution’ to the ‘Jewish problem’ needed to be organised sooner than had been originally envisaged. The deportations also partly led to the gas experiments at Chełmno, and heightened the Nazis’ sense of urgency to coordinate the policy towards Jews at the Wannsee Conference.

The Wannsee Conference, 1942

The Wannsee Conference Villa, where the Wannsee Conference took place on 20 January 1942. Courtesy of the David Allthorpe photo collection.

The Wannsee Conference Villa, where the Wannsee Conference took place on 20 January 1942. Courtesy of the David Allthorpe photo collection.

Courtesy of The Wiener Holocaust Library Collections.

The Wannsee Conference formalised the Nazis’ policy of the extermination of Jews in occupied Europe.

On 20 January 1942, leading Nazi officials met at the Wannsee Conference Villa in Wannsee, a south-western suburb of Berlin. The conference had been called to discuss and coordinate a cheaper, more efficient, and permanent solution to the Nazis’ ‘Jewish problem’. The conference was attended by senior government and SS officials, and coordinated by Reinhard Heydrich .

At the meeting, Heydrich gave a review of Nazis’ Jewish policy, highlighting the recent (September-October 1941) removal of the Jews from the German Reich, and framing it as a temporary solution to the larger Jewish problem.

The final plan for the eleven million Jews in remaining in Europe, as laid out by Heydrich, was to utilise them for work in the east on road works. Those who could not work, or became unable to work after a period of time, would be subject to special treatment. The Nazis used the term ‘special treatment’ as a euphemism for murder.

At the conference, there was also some discussion on the methods of mass murder, although concrete plans were not established. Experiments in using gas as a method of mass murder had already taken place at Chełmno in December 1941, but this was not mentioned and no one method was agreed upon within the meeting.

The meeting lasted approximately two hours.

Whilst the exact methods of mass murder were not laid out in this meeting, it played a significant role in coordinating the Nazis’ genocidal actions. The policy of annihilation to be taken against Jews was made extremely clear by the Nazi leadership. By the end of 1942, six extermination camps were in operation.

Creation of extermination camps, 1941 -1942

Following the Wannsee Conference, five additional extermination camps were adapted or established with the primary purpose of efficiently murdering the Jewish population of Europe.

This brought the total number of Nazi extermination camps to six. These extermination camps were:

  • Chełmno (in operation December 1941-January 1945)
  • Bełżec  (in operation March-December 1942)
  • Sobibór (in operation May-July 1942 and October 1942-October 1943)
  • Treblinka  (in operation July 1942-August 1943)
  • Majdanek  (in operation September 1942-July 1944)
  • Auschwitz-Birkenau  (in operation March 1942-January 1945)

In extermination camps, victims were murdered by being poisoned by gas. The process of murder was developed and adapted as each camp was built. For example, initially, at Chełmno, gas vans were used, but as the purpose-built extermination camps were established stationary gas chambers were found to be more effective.

Once they had arrived at the extermination camp, groups of Jews were typically separated into women and children, and then men. Some of the strongest were occasionally chosen for slave labour, but typically the majority were sent straight to the gas chambers where they were murdered.

In camps such as Auschwitz, most of those sent immediately to the gas chambers were told to leave their luggage and get undressed ready for disinfection in a shower. Approximately 1000 people were then shepherded into the false showers and an airtight door was closed. Carbon monoxide gas or Zyklon B was pumped into the room, and suffocated those inside. The bodies were then removed from the gas chamber and sent to the crematoria, and the lethal process began again.

The creation of the extermination camps marked the final, fatal, step in the Nazis’ journey towards genocide. In total, approximately three million people were murdered in the extermination camps. The deadliest extermination camp was Auschwitz-Birkenau, where approximately one million people were murdered.

Genocide in action, 1941-1945

From the summer of 1941 onwards, the situation for Jews and others viewed as inferior by the Nazis continued to rapidly deteriorate.


In Poland, the invasion of the Soviet Union meant that many of those incarcerated in ghettos were put to work manufacturing a variety of items for the war effort.  However, as soon as it became clear that the war would not be over quickly, the fate of the Jews trapped in the ghettos of Poland and eastern Europe was sealed. On 16 January 1942, the first set of deportations departed from the Łódź Ghetto, swiftly followed over the next two weeks by thirteen more transports, totalling 10,103 Jews. Almost all of them, except the 50-60 Jews who formed the Sonderkommado, were gassed shortly after arrival.

Four days after the first transport left Łódź, the Wannsee Conference took place, leading to the establishment of five more extermination camps. Genocide was unleashed as ghettos across Poland were emptied and Jews were sent to the extermination camps. In Warsaw,  between July and September 1942, approximately 300,000 inhabitants of the Warsaw Ghetto were deported to Treblinka and murdered.

The Soviet Union

Following the Einsatzgruppen ‘s initial advance into the Soviet Union and the resulting widespread massacres, many of the Jews who had been initially spared were forced into ghettos and used as slave labour. Those incapable of carrying out hard labour were murdered.

As Germany’s military advances slowed, the ruthlessness of the actions against the Jews and others seen as racial enemies of the Nazis radically increased. An example of this ruthlessness can be seen in the city of Kauna, Lithuania, where, on 4 October 1941, 1985 Jews were killed by Einsatzgruppen and local Lithuanian collaborators. Karl Jäger , leader of Einsatzkommando 3A, later reported that the massacre was in retaliation for the murder of a German policeman in the ghetto. Just under four weeks later, on 29 October 1941, a further 9,200 Jews were murdered in the city. They were forced to strip naked, with their belongings and valuables taken away, pushed into large pre-prepared mass graves, and then shot with machine guns. This time, Jäger reported that those murdered were surplus to requirements.

The murders in Kauna show the escalation of the Einsatzgruppen’s actions in the Soviet Union in late 1941, which continued to intensify and spiral out of control as war efforts struggled throughout the following years. By 1945, centuries of Jewish culture had been destroyed and thousands upon thousands of Jewish communities had been decimated .

Death marches, 1944-1945

As the Second World War progressed, the Nazis were pushed into retreat on both fronts.

From spring 1944 onwards, the Nazis ordered the forced evacuation of prisoners from camps across occupied Europe. These forced evacuations became known as death marches.

The Nazis ordered these evacuations for a number of reasons: in order to continue using the prisoners as slave labour in Germany; to use the prisoners to bargain peace with the Allies; and to stop survivors of the camps giving the Allies accounts of the horrors they had experienced.

Malnourished prisoners were forced to trek hundreds of miles on foot to camps into central Germany. Thousands of people died during the marches. Those who were unable to travel were murdered. Thousands more froze to death, starved or were shot on the way.

Liberation, 1944-1945

As the German Army started to lose the war, they were pushed into retreat towards Germany by the Allies. The Allies then began to liberate the hundreds of camps which the Nazis had constructed across occupied Europe.

On 23 July 1944, Majdanek, in eastern Poland, became the first extermination camp to be liberated by the Soviet Army. Abandoned quickly by the German forces, the camp was almost completely intact.

Over the following nine months, hundreds of camps were liberated across Germany and previously occupied territories, including extermination camps Auschwitz-Birkenau (by the Soviets in January 1945) and Bergen-Belsen (by the British in April 1945).

For many prisoners, liberation was only the beginning of their journey to freedom. The Nazis had stripped survivors of their jobs, their homes, and in many cases, murdered their families. Most had nowhere to go, and many ended up being placed in Displaced Person camps until they could eventually emigrate or settle elsewhere.

The conditions in the camps also took a while to improve because of the poor conditions in post-war Europe. Disease was widespread, and the daily death rate initially remained high. In Bergen-Belsen, 10,000 people died from malnutrition and disease after liberation.

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Deportation of German Jews, September 1941

Deportation of German Jews, September 1941

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