While there were only 23 main camps between 1933 to 1945, the Nazi regime established some 20,000 other camps used for forced labor, transit or temporary internment. During the Holocaust it is estimated that 6 million Jews were slaughtered along with, 3 million Soviet prisoners of war, 3 million Polish Catholics, 700,000 Serbians, 250,000 Gypsies, Sinti, and Lalleri, 80,000 Germans (for political reasons), 70,000 German handicapped, 12,000 homosexuals, and 2,500 Jehovah’s Witnesses.
On May 19th, 1939, the S.S. St. Louis sailed from Hamburg, Germany to Havana, Cuba with 937 passengers; almost all of them were Jews escaping with their lives. This was one of the last ships that left Germany before the outbreak of World War II. Most of the passengers had applied for U.S. visas and were only planning on staying in Cuba until they could enter into the United States. The U.S. State Department in Washington, the U.S. consulate in Havana, and the owner of the St. Louis were aware that they might not be able to enter Cuba, but the passengers were never told.
Trainloads of human cargo arriving at Auschwitz went through a selection process conducted by SS doctors such as Josef Mengele. Young adults considered fit for slave labor were allowed to live and had an ID number tattooed on their left forearm. Everyone else went to the gas chambers. A few inmates, including twin children, were occasionally set aside for participation in human medical experiments.
Several scholars have suggested that the Final Solution began in the newly formed district of Bezirk Bialystok. The German army took over Białystok within days. On Friday, 27 June 1941, the Reserve Police Battalion 309 arrived in the city and set the Great Synagogue on fire with hundreds of Jewish men locked inside. The burning of the synagogue was followed by a frenzy of killings both inside the homes around the Jewish neighbourhood of Chanajki, and in the city park, lasting until night time. The next day, some 30 wagons of dead bodies were taken to mass graves. As noted by Browning, the killings were led by a commander "who correctly intuited and anticipated the wishes of his Führer" without direct orders. For reasons unknown, the number of victims in the official report by Major Weis was cut in half. The next mass shooting of Polish Jews within the newly formed Reichskommissariat Ostland took place in two days of 5–7 August in occupied Pińsk, where over 12,000 Jews died at the hands of Waffen SS, not the Einsatzgruppen. An additional 17,000 Jews perished there in a ghetto uprising crushed a year later with the aid of Belarusian Auxiliary Police.
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.