What was the Holocaust? History and how it happened

The Holocaust was the systematic, state-organized persecution and murder of six million European Jews by Nazi Germany and its allies and collaborators between 1933 and 1945. The Nazi regime also persecuted and killed millions of other people it labeled enemies or inferior, including Roma, disabled people, Poles and Soviet prisoners of war. In Hebrew it is called the Shoah, "catastrophe".

In short

• About two in every three Jews living in Europe in 1933 were murdered, roughly six million of some nine million.
• It did not begin with death camps. It escalated over twelve years, from laws and boycotts to ghettos, mass shootings and gas chambers.
• It is one of the best-documented crimes in history, known from the perpetrators' own records, survivors, liberators and postwar trials.

How did persecution begin?

It began as law. Hitler came to power in January 1933, and within weeks the regime was building the tools of a dictatorship: the first concentration camp, at Dachau, opened in March, and on 1 April the Nazi Party organized a national boycott of Jewish shops. Laws that spring pushed Jews out of the civil service, the law courts and the universities.

The Nazis' ideology, a form of racist nationalism with roots in older antisemitism and part of what historians call fascism, treated Jews not as a religious group but as a "race" that threatened the German nation. The Nuremberg Laws of September 1935 wrote that idea into law. They reserved citizenship for people "of German or related blood", which left German Jews without political rights, and banned marriage and sexual relations between Jews and other Germans. Under the laws, anyone with three or four Jewish grandparents was a Jew, and a grandparent counted as Jewish by belonging to the Jewish religious community, the USHMM explains. A person's own baptism, or a lifetime outside any synagogue, made no difference.

On 9 and 10 November 1938, in the pogrom known as Kristallnacht, mobs and Nazi paramilitaries burned more than 1,400 synagogues across Germany and Austria and wrecked thousands of Jewish shops and homes. Police sent about 26,000 Jewish men to concentration camps, and hundreds of Jews died in the violence and its aftermath, according to the USHMM. Many Jews tried to leave. Emigration was hard: other countries, including the United States and Britain, kept tight limits on how many refugees they took.

How did it become mass murder?

War changed the scale. When Germany invaded Poland in September 1939, at the start of the war whose roots are traced in what caused World War 2, about two million more Jews came under German rule. The occupiers forced them into sealed ghettos, the largest in Warsaw, where hunger and disease killed tens of thousands before any deportation.

The turn to systematic killing came with the invasion of the Soviet Union in June 1941. Behind the front, SS and police units called Einsatzgruppen, with German army support and local collaborators, shot Jewish men, then women and children, at more than 1,500 sites. At Babi Yar, outside Kyiv, they killed more than 33,000 Jews in two days in September 1941. In all, the United States Holocaust Memorial Museum estimates, about two million Jews were murdered in mass shootings and related massacres.

From December 1941, the regime added killing centers built for one purpose. On 20 January 1942, at the Wannsee Conference, the SS official Reinhard Heydrich briefed 15 senior officials on coordinating the "Final Solution", which, the USHMM records, had already been decided at the top; he counted about 11 million Jews in Europe as falling under it. Trains then carried Jews from across occupied Europe to killing centers in occupied Poland, where most were murdered in gas chambers within hours of arrival.

Timeline: from law to genocide

Year	Step
1933	Hitler in power; Dachau opens; boycott of Jewish businesses; Jews expelled from the civil service
1935	Nuremberg Laws strip German Jews of citizenship
1938	Kristallnacht pogrom, 9–10 November
1939	War; ghettos set up in occupied Poland
1941	Mass shootings in the occupied Soviet Union; gassing begins at Chełmno in December
1942	Wannsee Conference, January; Bełżec, Sobibór and Treblinka begin killing
1944	More than 400,000 Hungarian Jews deported, most to Auschwitz, in under two months
1945	Camps liberated; Auschwitz on 27 January; Germany surrenders in May

Each step was taken by officials, police, railway workers, doctors and neighbors who carried out orders, profited, or looked away. Historians use that fact to explain how a modern state could organize murder on this scale.

How many people were killed?

The USHMM's figures break the six million down by how people died: about 2.7 million in the killing centers, about 2 million in mass shootings, 800,000 to 1 million in ghettos and camps, and at least 250,000 in other violence. Auschwitz alone accounts for about 1 million Jews, and Treblinka for about 925,000.

The regime killed millions of others as well. The museum's estimates include about 3.3 million Soviet prisoners of war, about 1.8 million non-Jewish Polish civilians, at least 250,000 and perhaps 500,000 Roma, 250,000 to 300,000 disabled people in institutions, and tens of thousands of political opponents, as well as gay men and Jehovah's Witnesses. Scholars differ on whether "the Holocaust" names the genocide of the Jews alone or all Nazi mass murder; both usages are found, and the museum treats the Jewish genocide as its center while documenting all the victims.

What is the evidence for what happened?

The evidence comes from several independent kinds of source that agree with one another. That is what makes the history solid.

Kind of evidence	What it shows
Perpetrators' records	Deportation lists, train timetables, Einsatzgruppen reports counting victims, the Wannsee minutes
Survivors' testimony	Tens of thousands of recorded accounts from many countries
Liberators	Soldiers, reporters and film crews who entered the camps in 1944 and 1945
Trials	Nuremberg (1945–1946), the Eichmann trial in Jerusalem (1961), the Frankfurt Auschwitz trials (1963–1965), which tried former Auschwitz staff in West Germany's own courts
Demography	Prewar and postwar population counts of Jewish communities
Physical sites	The remains of camps, gas chambers and mass graves

The Nazis tried to hide the crime, using euphemisms such as "resettlement" and, in 1943 and 1944, digging up mass graves to burn the bodies. Even so, no single document had to survive for the history to be known; it rests on all of them together. Holocaust denial, the claim that the genocide did not happen or was much smaller, is not a historical position with evidence behind it. Historians and courts have examined its claims and found them false, and it is widely understood as a form of antisemitism.

Why does the Holocaust matter now?

The Holocaust shaped the world after 1945. The word "genocide" was coined by the lawyer Raphael Lemkin in 1944, and the United Nations adopted the Genocide Convention in 1948. The Nuremberg trials established that following orders is no defense to crimes against humanity. Europe's surviving Jewish communities were small and scattered, and many survivors emigrated to the United States and to Israel, founded in 1948.

It also changed how people study the past. Holocaust history is a central case in how historians know what happened: it shows the value of combining perpetrators' paperwork with survivors' voices, and how evidence answers denial. Yad Vashem in Jerusalem and the USHMM in Washington keep the names of victims, gathering them one by one so that each is remembered as a person, not a number.

Check yourself

• Without looking back: name three steps that took the Nazi regime from persecution in 1933 to mass murder in 1941 and 1942.
• How did the Nuremberg Laws decide who was a Jew, and why did a person's own beliefs make no difference?
• What kinds of evidence let historians say with confidence that about six million Jews were murdered?

Sources

• Introduction to the Holocaust — United States Holocaust Memorial Museum
• Documenting numbers of victims of the Holocaust and Nazi persecution — United States Holocaust Memorial Museum
• Wannsee Conference and the "Final Solution" — United States Holocaust Memorial Museum
• The Nuremberg Race Laws — United States Holocaust Memorial Museum
• Kristallnacht — United States Holocaust Memorial Museum
• Thematic and chronological narrative of the Holocaust — Yad Vashem