IN-PERSON: An ideal visit to CHAIM would be in person. Visit the next in-person event. Or, bring it to your school, place of worship, or just about any working space that visitors can access. CHAIM’s message is too important, so we do not charge to bring CHAIM to you (though donations are always welcome).

Bring CHAIM to me! NEXT IN PERSON EVENT

VIRTUAL: Can’t come in person? Try one of these two online short-cut tours to get a taste of the message CHAIM aims to convey. Check your learning by doing taking this quizlet after or as you learn.

QUIZLET

VIDEO TOUR:

CHAIM 40 Min Overview Tour

Thank you: Filmed & Edited by Sammy Spector

READING TOUR:

You’re about to be taken on a journey. This journey consists of 18 portholes (stations) which give you glimpses of the Holocuast timeline from the beginning of the war to how we’re attempting to fulfill the motto “Never forget” today. As you journey, try learning the answers to the 18 key questions posed at each station, which will give you an overview of this journey. Click on the links for a deeper dive.

Intro

My name is Iris and I began creating this exhibit in 2007 in memory of the family I lost from both my mother (Danzig - Germany) and father’s side (Kishinev - Moldova) during WWII. I didn’t know about this history growing up; it was never discussed. The Holocaust happened because of hate, so just remembering what happened isn’t enough. The hope is that your journey through CHAIM will also inspire you to take action to fight against hate through acts of compassion, empathy and with your knowledge of the facts. Test your knowledge by seeing if you can answer the 18 CHAIM station key questions at the end of your journey.


Stations 1-9: World War II and Nazi Rule

STATION 1 • VIEW POSTER

Why do we study the Holocaust?

When you come to an exhibit such as this you should ask yourself why you are visiting, and what questions you’d like answered?

The Holocaust was the WORST GENOCIDE humans have ever initiated. 6 million Jewish men, women, and children were murdered just because they were Jewish. An additional 5 million people were also killed because they had some other trait the Nazis considered “undesirable” such as being of Slavic decent, Russian, Roma, gay, disabled, a person of color, or Catholic. Because the Jews were the most specifically targeted, this exhibit looks at the Holocaust through the Jewish lens, however, we should always remember that Nazis swept other minorities into their cauldron as well. They exhibited RACISM to its fullist extent.

So we must study the Holocaust, not only to remember those who were tortured and murdered, but also to learn how to make things better in the future.  The Holocaust, as horrible as it was, is just one of many genocides that have occurred and are still occurring in the world. Learning this history and hearing the testimonials of those who survived, is not only important to memorialize those who were murdered, but also to inspire us to action, and to fight the hatred that leads to genocide.

At CHAIM we use the acronym WAKE UP to remind us of some actions we can take. Before continuing be sure you ‘register’ in your mind what are the 6 actions that WAKE UP reminds us to take - because that is a main reason for this journey.

We also open the exhibit with a look at the moment that started it all. Click on View Poster above, and see just how easy it could be to lose a democracy and the freedoms we hold so dear. Learning about the Holocaust and understanding what leads people to elect officials with extreme views, might help us prevent such events in the future. Its happening before our eyes, so we must WAKE UP!


STATION 2 • VIEW POSTER

What was Jewish life like before the War?

Let’s begin our Holocaust journey by looking at what life was like prior to the Nazi takeover in 1933.

In 1933, approximately 9.5 million Jews lived in Europe. This comprised of only 1.7% of the total European population but 60 percent of the world's Jewish population at that time, estimated at 15.3 million. Jews could be found in all walks of life, as farmers, tailors, seamstresses, factory hands, accountants, doctors, teachers, and small-business owners. Many were soldiers and fought alongside their countrymen in WWI. Some families were wealthy; many more were poor.

Take a look at where Jews lived pre-WWII: Map of Jewish population of Europe

In Western Europe (Germany, Hungary, Austria, France, Holland…) Jews enjoyed being fully integrated into society, especially German society. Jews had non-Jewish friends and neighbors, Jewish children went to school with non-Jewish children, and were best friends with non-Jewish children. In THIS POSTER OF THE SANDLER SISTERS you can see that my grandmother’s sisters and their families who lived in Danzig, part of Germany at the time, were well dressed, and seemed to live like everyone else.

In Eastern Europe (Poland, FSU - Formed Soviet Union - Russian, Ukraine, Moldova etc), many Jews lived in small villages called shtetls and were subjected to period anti-Semitic riots called pogroms. Even those who lived in the big cities and were not poor like shtetl Jews tended to live separately from the non-Jewish residents. In THIS PHOTO OF THE BALTSAN FAMILY my father’s grandparents, parents, aunts and uncles who lived in Kishinev, now Moldova, posed for a last photo before some of the younger members decided to leave for Palestine (Israel before it became a state), as the situation for Jews was worsening. You can tell by their clothing, that these Eastern European Jews were not as wealthy as the the Western European Jews. They sensed it was time to leave as early as 1935, as their life as Jews was much more difficult and they did not have patriotism of the German Jews keeping them there.

Many Jews also lived in relative peace with their neighbors in the Balkan countries (Greece, Bulgaria, Yugoslavia, Albania).

By the end of WWII 2 of every 3 Jews of Europe would be killed, and the Jewish landscape of Europe would be changed forever. Except for my maternal grandparents and my mother, all my mother’s maternal relatives in Danzig were murdered by the Nazis. All my father’s maternal relatives in Kishinev with the blue star in the photo, were murdered by the Nazis. Imagine how large my family could have been.

On the other hand, because some were able to escape, me and my family are alive today, and that’s why this exhibit is called ‘CHAIM’, or LIFE in Hebrew. Ultimately, learning about the Holocaust is less about the death that happened, and more about learning how important TACT* is for life!

  • part of the WAKE UP motto: Treating others with Acceptance, Compassion and Tolerance.


STATION 3 • VIEW POSTER

How could an extreme party like the Nazis win a democratic election?

How was it that the Nazis could take power in a democracy like Germany? Why did such a high percentage of the vote support the Nazi party so that a person like Hitler was offered the chancellorship?

Hitler campaigned on a promise “to make Germany great again’”. He didn’t specify how; but people believed him just because they wanted change. Check out Reasons and remember ‘the grass isn’t always greener’ just because someone says they will make it greener.

There are several publications still out there which provided fuel for the fire called the Holocaust. These were written BEFORE the Holocaust. Fuel for Anti-Semitism.

Hitler actually began his take over in 1933 when he became chancellor of Germany. Over the next few years, he transformed the German democracy into an iron fisted dictatorship implementing new laws which encouraged the persecution of ‘undesirable’ groups within the population. Hitler defined ‘undesirables’ as anyone who not part of the “Aryan Race”, a made up race of white, mostly blond and blue-eyed people. White Supremacy at its ‘best’!

Who helped him achieve this transformation? Hitler gave himself the title of Fuhrer (absolute leader), surrounded himself with powerful followers who created a willing police (Gestapo) and private army (SS), and made it mandatory for all kids to be part of the Hitler youth. Hitler's Helpers

In what ways did they achieve power:

  • Capturing other countries to create ‘living space’ (Lébensraum) for Germans. The first was the annexation of Austria (called the Anschluss), followed by Czechoslovakia.

  • Implementing laws which gradually excluded Jews and other undesirable people from German life (Nuremberg Laws).

  • Eliminating their obligations for starting WWI under the Treaty of Versailles (like keeping the size of the army at a minimum, and paying reparations).

  • Propaganda - spreading false information about minority groups through ads, cartoons, books, radio, education.


STATION 4 • VIEW POSTER

Why was Kristallnacht allowed to happen?

In early 1938, political representatives from 32 countries met in the French spa town of Evian to discuss how to deal with the influx of refugees leaving Germany. The conference failed to produce a solution and thus Hitler was emboldened. He concluded that if the countries of the world were not willing to accept the Jewish refugees it meant that they didn’t care what happened to them and he could do whatever he wanted.

The Holocaust officially began shortly after Evian, with Kristallnacht, the Night of Broken Glass, on November 9, 1938. Germany stated that this ‘pogrom’ was in retaliation of the assassination of German foreign official Ernst vom Rath, who had been shot two days earlier by Herschel Grynszpan, a 17-year old Polish Jew distraught over the deportation of his family from Germany. In truth, Joseph Goebbels, the German propaganda minister, was just waiting for a good excuse to unleash a plan which was pre-set. It was only after this day, when police stood by as pre-planned looters smashed Jewish synagogues and businesses, that many patriotic Jews realized that this wasn’t just ‘plain old’ anti-Semitism, and it was time to get out of Germany. But at this time it was nearly too late as Germany itself began closing its borders to escaping Jews.

And this is why its so important that the world not let history repeat, and democracies must stand up to the aggression by dictatorial leaders by accepting refugees needing to escape persecution.

Check out the Yad Va'Shem Exhibit on Kristallnacht.


STATIOn 5 • VIEW POSTER

How were Jews persecuted during WWII?

Persecution is a program or campaign to exterminate, drive away, or defeat a people because of their religion, race, or beliefs.

Jews have been persecuted in the various countries they have lived in for centuries.   Sometimes the persecution has been mild, sometimes severe.  In Spain in 1492, Jews were expelled from the country unless they converted; in Russia during the late 19th - early 20th century severe pogroms often forced Jews to leave their homes after their villages were set on fire and looted (think “Fiddler on the Roof”).  After Kristallnacht the Nazi government felt bold enough to increase the severity of the persecution of the Jewish people in Germany, and try to increasingly isolate them from the mainstream community.

Hitler’s implementation of anti-Jewish policies to isolate the Jews from the mainstream can be divided into 3 phases:

  1. Boycotts & Civil Service Law - including anti-Jewish propaganda (cartoons, posters, books etc.), wearing yellow star, excluding from workplaces and schools.

  2. Racially Based Laws - Nuremberg Laws

  3. Aryanization - transferring Jewish property to “Aryans”


STATION 6 • VIEW POSTER

In what ways were Jews deported?

The catastrophe to befall the Jews of Western Europe began in earnest in early 1942 with deportation,

Deportation is the act of expelling a person from one’s hometown or country to somewhere else.

One of the most horrible aspects of the Holocaust was the deportations of Jews from their home countries.  This took place from German-occupied countries, and from states allied with Germany. By giving the Jews these “choice-less choices”*,  Nazis revealed that their goal was not only to deprive Jews of their human rights, but also their human dignity. This is called ‘dehumanization’.

The choice-less choices the Jews faced were:

Choice-less choice 1 - GHETTOS:

Choice-less choice 2 - CATTLE CARS:

Choice-less choice 3-CONCENTRATION/ DEATH CAMPS:


And why wouldn’t the Jews simply leave Germany?

It was not so easy!

After Kristallnacht in 1938, most Jews still in Germany realized it was time to leave. Only about half of Germany’s Jews had emigrated in the preceding years, now the Jews who remained had a more difficult time leaving the country because emigration policies had been toughened, doors were closing, and they encountered these stumbling blocks:

Passports & Money

Visa Quotas

Refugees turned away


STATION 7 • VIEW POSTER

How was the Final Solution implemented?

At the Wannsee conference in January of 1942, the Nazis formulated their systematic methodology to murder all the Jews, the plan referred to as "The Final Solution." The ‘solution’ called for the murder of all European Jews by two major methods.

  1. Killing Centers: Transport of Jews crammed into cattle cars took them by railroad from their home towns and ghettos, to concentration camps and killing centers mostly in Poland (Belzec, Sobibor, Treblinka, Chelmo, and Auschwitz, the most infamous), often many days of travel away. At the killing centers, the Nazis were able to murder many people a day in gas chambers.

  2. Einsatzgruppen: Mass shootings of Jews just outside their hometowns by mobile killing “death” squads called Einsatzgruppen who were sent geographically throughout a huge swath of Eastern Europe (Western Russia, Baltic states, Belarus, Ukraine, Moldova, and Poland).

  3. Death Marches: Even when the Nazis started losing the war, they made their prisioners walk for days to make their way from camps near areas that were being liberated, to camps in Germany. These were called Death Marches, as many of the prisioners who managed to survive the brutalities of the concentration camps, died of starvation, exhaustion and exposure during these marches.

Of the 6 million Jews murdered by the Nazis, 2.7 million died at concentration camp killing centers, at least 2 million were murdered by the Einsatzgruppen in what is known as the “Holocaust by Bullets”.

In this time when we see leaders with autocratic tendencies succeeding in gaining a strong following, we should heed the warning of the Wannsee conference. Read THIS article! Contemplate! Could a people who are maybe 0.2% of the world population, and who could be rounded up to have 40% of them murdered in such a horrific way, truly be in control of the world!? Humans seem to need a scapegoat - someone to blame for their woes - a minority group is an easy scapegoat.

And despite the many mass graves that have been found, and now labeled as such, despite converting killing centers such as Auschwitz into museums, there is a growing movement called Holocaust Denial. This is the belief that the Holocaust either didn’t happen, or was exaggerated by Jews in order to gain favors.

We study the Holocaust so we have the knowledge to counter deniers. Imagine surviving the horrors, and then to watch as people try to deny what you lived through. Most survivors are quite old, will the next generation be able to keep history straight despite denial becoming so strong while survivors are still alive??

And this is why we still see genocides happening again and again. Humanity needs to stop blaming others, and work together to solve problems through compromise and a view that “we are all in this together”. WAKE UP!!


STATIOn 8 • VIEW POSTER

How did people resist the Nazis?

It used to be asked why did the Jews go to be slaughtered like sheep? In actuality, those who could did resist. Resistance to the atrocities of the Nazis came in different forms. Some examples:

  1. The sheer will to survive of the prisoners who were being starved and forced to work to death, is a form of resistance. Often they helped each other secretly though they could be shot for doing so (see Stealth Altruism).

  2. Uprisings. The most famous is the Warsaw Ghetto Uprising; the Jews inside help up against the Nazis for nearly 3 weeks.

  3. Jewish partisans who lived in frigid forests and used their ingenuity to wreak havoc on German transports.

  4. Jews who at great risk to themselves, stayed in dangerous areas to help especially children escape to safety, or joined the “Hagana” to take Jews to Palestine illegally. Hannah Senesh was an example of Jew from Israel who parachuted back into Europe to try to save Jews.

  5. Giving your child away. Parents made the courageous choice to send their kids away so at least they could survive. Some were sent via the Kindertransport to England, some where sent to live with non-Jews who were willing to pretend the kids were relatives, or hide them in another way. In most cases the children survived and never saw their parents again.

  6. Non-Jews who were empathetic, and thus willing to risk their lives to do the right thing by hiding Jews in their homes, helping Jews cross treacherous mountain passes to neutral countries, making false passports and many other risky and creative ways to help Jews survive. Israel’s Holocaust museum, Yad Va’shem, has been honoring non-Jews who rescued Jews during the Holocaust. These people are referred to as The Righteous Among the Nations (or Righteous Gentiles). As of 2021, 27, 921 people have been honored.

  7. Writing dairies, hiding artwork, taking photographs to document was was happening.

All these were forms of resistance to the Nazi killing machine.


STATION 9 • VIEW POSTER

Why did it take so long to liberate the camps?

Once the tide of the war turned, it still took the 'allies' several years to ‘win the war’. The turning point began with the Japanese bombing of the U.S. naval base in Pearl Harbor, Hawaii in December of 1941. It was only after this attack that the United States joined ‘the Allies” - Great Britain and the Soviet Union to put enough pressure on the Germans to stop their takeover of Europe and push them back into Germany. The largest operation called Operation Overlord, was the coordinated allied invasion of Normandy, France by sea, followed by an airborne operation on June 6, 1944. After “D-Day” it still took until April of 1945 to recapture the countries that had been taken over by the Nazis and liberate the prisoners from the concentration camps (VE Day).


Stations 10-12: Fighting Hate

STATION 10 • VIEW POSTER

To where could the Jews go after the war?

There were 4 choices:

  1. Go back home: Although for the most part the non-Jewish prisoners were able to go back to their homes, for the Jewish prisoners this was rarely an option. There was no going back to what was as either their homes had been taken over by other people, or they simply were not welcome to return. In Poland, pogroms occurred even after the war to people who tried coming back ‘home’.

  2. Get a visa to another country: most countries had limited annual quotas. So some had to wait for years to get a visa. To get a visa to the United States you had to have family members already here to sponsor you.

  3. Most lived in Displaced Persons (DP) camps - usually converted concentration camps - until they either were able to get hard to get visas to other countries, or took illegal refugee ships to Palestine (now Israel). The last DP camp was not shut down until 1959, 14 years after the end of the war.

  4. Go to Israel - Only in 1948, when Israel became a state, were many more able to finally immigrate to the Jewish State legally and start living again. Before that, many Jews were brought to Israel through Aliyah Bet - Ilegal immigration. One of the important reasons Jews were so determined to see the State of Israel re-established was so there would finally be one place in the entire world that Jews would be welcomed, no visa needed, and no persecution as they had experienced pretty much in every country since their expulsion from Jerusalem in 70 CE.

Jews are often asked to ‘return to where you came from’! Where is that exactly?? Study the Poster from Station 5… what do you think?


STATIOn 11 • VIEW POSTER

Is justice for such a crime possible?

Is it possible for justice to be served for such a horrendous crime as genocide? It is not possible to bring the lost family, lost decendents, or even lost property back. Yet some things were done to bring some justice to the victims.

The Nuremberg trials put 199 Nazi commanders to trial. 161 were convicted, 24 were sentenced to death and 20 were given life sentences. The Ferencz trials put commanders of the Einsazgruppen to trial. The Simon Wiesenthal center was created to hunt down Nazis living in hiding around the world.

Germany is still paying reparations to victims, their families and to Israel for this crime.


STATIOn 12 • VIEW POSTER

How can we fight the hate that leads to genocide?

After the Holocaust, humanity cried out 'Never Again' shall genocide occur. Yet, here we are in the 21st century and we still hear of genocide after genocide, not to mention so many ‘small scale’ hate crimes. In the United States, a country that is a beacon for freedom, intolerance is not only flourishing but increasing: Homophobia Islamophobia AAPI Indigenous Peoples Black Lives anti-Semitism

Anti-Semitism is the oldest form of hate. A society that tolerates hate such as anti-Semitism, is susceptible to other forms of racism, hatred and oppression. Hate leads to intolerence, which leads to genocide.

The only way to prevent the hate that leads to genocide is to teach people to “Wake Up” - Witness, Act with Tact, Know, Empathize, Upstand and Prevent. This has to start young! Empathy training is a thing now! Want to learn to be more tolerant? Accepting? Join anti-Hate opportunities such as marches against hate!

WAKE UP is our remedy for the hate and hunger for power that allows racism and genocide to occur. Especially people living in democratic countries must beware when authoritarian candidates run for a democratically elected position, or if officials try to curtail rights of minorities (we see this now in the US with voting rights, the right to choose, and other intolerant policies being pushed by people in power). If a power-hungry person, who wants to impose their way or no way, is cunning enough to be elected, democracy can fall and take with it the freedoms we hold dear. Venezuela’s take over by Hugo Chavez, Saddam Hussein’s take over of Iraq, Kim Il-Sung’s take over of N. Korea are just a few examples!! Let’s not let it happen in the United States. Use your voting power wisely!

The United States is home to hundreds of hate groups such as the Neo-Nazis, Skinheads, Proud Boys, Aryan Nation, KKK, Alt-right etc. They choose facts selectively in order to promote their agenda. They use the internet and social media to feed their readers propaganda. And just like Hitler and the Nazis, they can persuade people who choose not to fact check, or learn the truth, of just about anything.

This is why WAKE UP is the remedy. When you know the facts, you can identify extremist ideologies and theories and not be persuaded that they are ‘truth’.


Stations 13-16 & 18: To Never Forget

STATION 13 • VIEW POSTER

Can art be a witness to crime?

The living aren't the only witnesses to crime.  From poetry and paintings to photographs and film, art forms are primary source witnesses to the Holocaust.  Art helps express what words perhaps cannot.

When troops from the United States armed forces started liberating the camps, they could not believe the horrible sites they saw. General Eisenhower who oversaw the entire Allied operation (and later became president), actually ordered the media to take so that no one could ever deny what had happened. Luckily, because Holocaust Denial, is a real ‘thing’ today. Leni Riefenstahl was Hitler’s personal photographer who also produced various propaganda films for the Nazi Party which are still around.

Diaries that were written by teens in the ghettos and camps, bare witness to life in these places. Anne Frank Rywka Lipszyc Other Holocaust diaries


STATION 14 • VIEW POSTER

Can we be witnesses after all the survivors had passed on?

The best way to try to understand what it was like to live through the Holocaust is to hear a survivor tell their personal story. However, as we come closer to the post-survivor era, reading their testimonials, or speaking with their decedents, still allows us to become the witnesses to tell the survivor account even after they are gone. Take the time to get to know a survivor or two through their fascinating stories of resistance and luck. Click HERE for local survivor accounts. Check out Project Spotlight - you can pass on a survivor story!


STATION 15 • VIEW POSTER

What purpose do the many Holocaust memorials and museums serve?

Jewish tradition honors keeping the memory of loved ones alive through several ritual practices. Thus it is not surprising that there are so many Holocaust memorials and museums to keep the memory of the millions who died alive, to honor those who tried to help them, and to remind us of the need to WAKE UP. Most of the concentration camps have memorials associated with them that people can visit, however, the mass graves of the Jews killed by the “Holocaust by Bullets”, are often hundreds, even thousands of unmarked fields, forests and ravines. Museums, as well as some cities and counties, host annual educational and memorial programs for teachers, and the community at large.

Hate occurs through ignorance. Memorials and museums can help educate. 94 Maidens Mandate Video

Some important museums include:

USHMM - the United States Holocaust Memorial Museum

Yad Va’shem - Israel’s Holocaust Museum

By visiting these places, and taking to heart what we learn, we can serve as witnesses in the post-survivor era.


STATIOn 16 • VIEW POSTER

What prevents the rebuilding of lost Jewish communities of Europe?

As of 2022 world Jewish population (0.2%) has just reached its pre-WWII levels of 15 million with 7 million living in Israel, 6 million in the US, and the remaining 2 million spread around the world. For centuries Jewish life flourished in Europe, with about 40% of world Jews living in Europe pre-WWII. However, with 85% of Europe’s Jewish population murdered during the Holocaust, and the rise of anti-Semitism, today only about 1 million Jews call Europe home.

Poland, a country where 3 million Jews called home prior to WWII and where core Jewish knowledge was born, has a Jewish population of about 10,000. Yet, despite the 1968 “purge”, where 15, 000 Polish, Jewish citizens were stripped of citizenship and forced to leave, Poland’s Jewish population is rebuilding. Many of its citizens are finding they actually have Jewish roots, and there is a renewal of interest in Poland’s rich Jewish heritage so much so that Poland now hosts each summer, the biggest, annual Jewish Culture festival in the world. In 2013 it opened the Museum of the History of the Jews of Poland (Polin), on site of the former Warsaw Ghetto.

Ukraine, which was home to about 1.5 million Jews pre-WWII, was a horribly anti-Semitic area then. Since then, the society has become much more tolerant, even has a Jewish president, a Jewish population of 100,000, who until this current war in Ukraine, never thought they’d have to run from their homes again.

On the other hand, France, which post-WWII used to have the 3rd largest population of Jews behind the US and Israel, now has a Jewish exodus due to a resurgence of anti-Semitism there, although this is a newer anti-Zionism form of anti-Semitism as opposed to the old style Christian anti-Semitism.

The oldest hatred - anti-Semitism - still impacts the rebuilding of Jewish communities in the 21st century.


STATIOn 17 • VIEW POSTER

How did children survive the Holocaust?

1.5 million Jewish children were murdered during the Holocaust. However, some managed to survive, how?

Kindertransport - one important project that helped many children survive was the transporting of children from German-occupied areas to England. After Kristallnacht, Britain agreed to transport (mostly by train, some by plane) of minors to England. Over the course of nearly 2 years about 10,000 children were rescued from the Nazis in this way. They did have to leave their family behind, and most never saw their family again.

Hiding - children were saved by hiding with non-Jewish families, or even hiding in plain sight by pretending to be a member of the non-Jewish family. Children had to learn their ‘new’ identities, new names, new religion, and be very careful not to ‘slip up’.

At this station you’ll find an array of children’s books about the Holocaust. Each represents a story of survival of a child of the Holocaust.

Click HERE to view Yad Va’shem’s “Children in the Holocaust” Exhibit.


STATION 18 • VIEW POSTER

How can you use what you learned, and WAKE UP to fight hate?

Now that you’ve learned what the Holocaust was, it is important to take action.  Genocide, hate and intolerance still flourish in this world; yet as brutal as the Nazi actions were during this time, there were many acts of virtue as well and it is from these that we must learn.  People who made the choice not to stand by and follow the crowd, but to do what was right are called upstanders. Can you take on the “WAKE UP” mission -  and never stand idly by and watch hate in action?

Are you able to answer the Quizlet questions now??

 
 

Explore the Timeline of the Holocaust