Once Germany took over Poland in 1939, it created forced-labor camps. Thousands of prisoners died from working conditions, exhaustion, and starvation. After the outbreak of World War II, the number of concentration camps increased exponentially. The number of prisoners of war camps also rose, but after the first years of the war most were converted into concentration camps. Nazis forcibly relocated Jews from ghettos to concentration camps.
The nature and timing of the decisions that led to the Final Solution is an intensely researched and debated aspect of the Holocaust. The program evolved during the first 25 months of war leading to the attempt at "murdering every last Jew in the German grasp".[5] Most historians agree, wrote Christopher Browning, that the Final Solution cannot be attributed to a single decision made at one particular point in time.[5] "It is generally accepted the decision-making process was prolonged and incremental."[6] In 1940, following the Fall of France, Adolf Eichmann devised the Madagascar Plan to move Europe's Jewish population to the French colony, but the plan was abandoned for logistical reasons, mainly a naval blockade.[7] There were also preliminary plans to deport Jews to Palestine and Siberia.[8] In 1941, wrote Raul Hilberg, in the first phase of the mass murder of Jews, the mobile killing units began to pursue their victims across occupied eastern territories; in the second phase, stretching across all of German-occupied Europe, the Jewish victims were sent on death trains to centralized extermination camps built for the purpose of systematic implementation of the Final Solution.[9]
Transportation between camps was often carried out in freight cars with prisoners packed tightly. Long delays would take place; prisoners might be confined in the cars on sidings for days.[190] In mid-1942 work camps began requiring newly arrived prisoners to be placed in quarantine for four weeks.[191] Prisoners wore colored triangles on their uniforms, the color of the triangle denoting the reason for their incarceration. Red signified a political prisoner, Jehovah's Witnesses had purple triangles, "asocials" and criminals wore black and green. Badges were pink for gay men and yellow for Jews.[192] Jews had a second yellow triangle worn with their original triangle, the two forming a six-pointed star.[193][194] In Auschwitz, prisoners were tattooed with an identification number on arrival.[195]

Most Holocaust historians define the Holocaust as the enactment, between 1941 and 1945, of the German state policy to exterminate the European Jews.[a] In Teaching the Holocaust (2015), Michael Gray, a specialist in Holocaust education,[27] offers three definitions: (a) "the persecution and murder of Jews by the Nazis and their collaborators between 1933 and 1945", which views the events of Kristallnacht in Germany in 1938 as an early phase of the Holocaust; (b) "the systematic mass murder of the Jews by the Nazi regime and its collaborators between 1941 and 1945", which acknowledges the shift in German policy in 1941 toward the extermination of the Jewish people in Europe; and (c) "the persecution and murder of various groups by the Nazi regime and its collaborators between 1933 and 1945", which includes all the Nazis' victims. The third definition fails, Gray writes, to acknowledge that only the Jewish people were singled out for annihilation.[28]
Those who were not considered fit for work were taken immediately by truck from the Judenrampe to two make-shift gas chambers at Birkenau, which were located in two converted farm houses called "the little red house" and "the little white house." At least 75% of the Jews in each transport of 2,000 to 3,000 prisoners were deemed unfit for work and were destined for the gas chamber. The little red house, also known as Bunker 1, had a capacity of 800 people in two rooms and the little white house, called Bunker 2, had a capacity of 1,200 in four rooms.
Hitler targeted the Jews for a specific reason, which was not just racial. The elimination of the Jews had a unique “status” in Hitler’s master plan. While he certainly killed millions of others (gypsies, communists, homosexuals, etc.) he made exceptions for all these groups. The only group for which no exception was made was the Jews—they all had to die.
Dr. Mengele was nicknamed the "Angel of Death" by the prisoners because he had the face of an angel, yet he callously made selections for the gas chambers at Birkenau. He was nice to the children in the camp, yet he experimented on them as though they were laboratory rats. He volunteered to do the selections at Birkenau, even when it wasn't his turn, because he wanted to find subjects for his medical research on genetic conditions and hereditary diseases, which he had already begun before the war. He particularly wanted to find twins for the research that he had started before he was posted to Birkenau.
But how he would enact such a plan wasn’t always clear. For a brief period, the Führer and other Nazi leaders toyed with the idea of mass deportation as a method of creating a Europe without Jews (Madagascar and the Arctic Circle were two suggested relocation sites). Deportation still would’ve resulted in thousands of deaths, though perhaps in less direct ways.
But how he would enact such a plan wasn’t always clear. For a brief period, the Führer and other Nazi leaders toyed with the idea of mass deportation as a method of creating a Europe without Jews (Madagascar and the Arctic Circle were two suggested relocation sites). Deportation still would’ve resulted in thousands of deaths, though perhaps in less direct ways.
Hitler quickly moved to cement his power by suspending many civil liberties and allowing imprisonment without trial. By March, the first Nazi concentration camp was established at Dachau, not to imprison Jews but to hold political dissidents. Further laws targeted Jews, restricting the jobs they could hold and revoking their German citizenship. Anti-Semitic sentiment increased as the Jewish population was blamed for many of Germany's recent and historical problems.
Before the start of World War II, around 9.5 million Jewish people lived in Europe. By the time the war ended, the Nazis had killed 6 million European Jews in concentration camps, or pogroms, or ghettos, or mass executions in what we refer to today as the Holocaust. The Nazis used the term Endlösung, or Final Solution, as the “answer” to the “Jewish question.” But when did this monstrous plan get put in motion?
During his time at Auschwitz, Josef Mengele was not the only physician there. It is popularly believed that he was the highest-ranking physician at the camp. This is not the case. That “distinction” belonged to SS captain Dr. Eduard Wirths. Wirths’ position as garrison physician made him responsible in all medical matters for the entire camp complex.
Three defendants were acquitted. However, many of the Nazis who perpetrated the Holocaust were never tried or punished, including Hitler who had committed suicide. Since then, the international community has continued and improved accountability through forums such as the International Criminal Court, and the International Criminal Tribunal for Rwanda.
This is not about people acting out a crime of passion. This is planned and rationalized violence — a cultural brainwashing. The rationalization is always that the victims are not truly human, not worthy of the same protections of the law. It’s interesting that the Nazis are often linked to Christianity, especially the Catholic Church. But it is precisely the teachings of the Church that stand in the way of such dehumanization. This is something that Mengele himself knew, as he was raised in a Catholic family. In fact, in his post-WWII journal, Mengele specifically wrote, “We had to liberate Germanic history from Roman and Catholic influences.”
On July 5, 1942, Anne's older sister Margot received an official summons to report to a Nazi work camp in Germany, and on July 6, Margot and Anne went into hiding with their father Otto and mother Edith. They were joined by Hermann van Pels, Otto's business partner, including his wife Auguste and their teenage son Peter.[12] Their hiding place was in the sealed-off upper rooms of the annex at the back of Otto's company building in Amsterdam.[12][13] Otto Frank started his business, named Opekta, in 1933. He was licensed to manufacture and sell pectin, a substance used to make jam. He stopped running his business while everybody was in hiding. But once he returned, he found his employees running it. The rooms that everyone hid in were concealed behind a movable bookcase in the same building as Opekta. Mrs. van Pels's dentist, Fritz Pfeffer, joined them four months later. In the published version, names were changed: The van Pelses are known as the Van Daans, and Fritz Pfeffer as Albert Dussel. With the assistance of a group of Otto Frank's trusted colleagues, they remained hidden for two years and one month.
In February 2010, a 180-page volume of Mengele's diary was sold by Alexander Autographs at auction for an undisclosed sum to the grandson of a Holocaust survivor. The unidentified previous owner, who acquired the journals in Brazil, was reported to be close to the Mengele family. A Holocaust survivors' organization described the sale as "a cynical act of exploitation aimed at profiting from the writings of one of the most heinous Nazi criminals".[118] Rabbi Marvin Hier of the Simon Wiesenthal Center was glad to see the diary fall into Jewish hands. "At a time when Ahmadinejad's Iran regularly denies the Holocaust and anti-Semitism and hatred of Jews is back in vogue, this acquisition is especially significant", he said.[119] In 2011, a further 31 volumes of Mengele's diaries were sold—again amidst protests—by the same auction house to an undisclosed collector of World War II memorabilia for $245,000 USD.[120]

According to a news article in the Quad-City Times, Yanina Cywinska survived the gas chamber at Auschwitz when she was 10 years old. Cywinska presented the Geifman Lecture in Holocaust Studies at the Augustana College in Rock Island, IL on April 11, 2005, sharing her firsthand account of the atrocities that she endured as a prisoner in Auschwitz and later at Dachau.
As of 1 January 2006, Yad Vashem had recognized 21,310 persons as Righteous Gentiles. Poles formed the largest group, with 5,941 having been recognized. Other East Europeans came from Ukraine (2,139), Hungary (671), Lithuania (630), Belarus (564), Slovakia (460), Russia (120), Czech Republic (115), Latvia (100), Moldova (71), Romania (52), and Estonia (3). Yad Vashem cautions, however, that its figures do not represent the actual number of people who rescued Jews in each country. For example, gentiles who saved Jews for financial gain are excluded. Thus many more people rescued Jews than are officially recognized. Because Poles constitute by far the largest group of Righteous Gentiles, they have been the most extensively studied, and most of the following observations are based on data concerning them.
Mengele joined the Nazi Party in 1937 and the Schutzstaffel (SS; protection squadron) in 1938. He received basic training in 1938 with the Gebirgsjäger (light infantry mountain troop) and was called up for service in the Wehrmacht (Nazi armed forces) in June 1940, some months after the outbreak of World War II. He soon volunteered for medical service in the Waffen-SS, the combat arm of the SS, where he served with the rank of SS-Untersturmführer (second lieutenant) in a medical reserve battalion until November 1940. He was next assigned to the SS-Rasse- und Siedlungshauptamt (SS Race and Settlement Main Office) in Poznań, evaluating candidates for Germanization.[18][19]