Because they refused to pledge allegiance to the Nazi party or serve in the military, Jehovah's Witnesses were sent to concentration camps, where they were identified by purple triangles and given the option of renouncing their faith and submitting to the state's authority.[447] The United States Holocaust Memorial Museum estimates that between 2,700 and 3,300 were sent to the camps, where 1,400 died;[411] in The Holocaust Encyclopedia (2001), Sybil Milton estimates that 10,000 were sent and 2,500 died.[412] According to German historian Detlef Garbe, "no other religious movement resisted the pressure to conform to National Socialism with comparable unanimity and steadfastness."[448]
If Anne Frank had not perished in the criminal malevolence of Bergen-Belsen early in 1945, she would have marked her sixty-eighth birthday last June. And even if she had not kept the extraordinary diary through which we know her it is likely that we would number her among the famous of this century—though perhaps not so dramatically as we do now. She was born to be a writer. At thirteen, she felt her power; at fifteen, she was in command of it. It is easy to imagine—had she been allowed to live—a long row of novels and essays spilling from her fluent and ripening pen. We can be certain (as certain as one can be of anything hypothetical) that her mature prose would today be noted for its wit and acuity, and almost as certain that the trajectory of her work would be closer to that of Nadine Gordimer, say, than to that of Francoise Sagan. As an international literary presence, she would be thick rather than thin. “I want to go on living even after my death!” she exclaimed in the spring of 1944.
In nearly every country overrun by the Nazis, the Jews were forced to wear badges marking them as Jews, they were rounded up into ghettos or concentration camps and then gradually transported to the killing centers. The death camps were essentially factories for murdering Jews. The Germans shipped thousands of Jews to them each day. Within a few hours of their arrival, the Jews had been stripped of their possessions and valuables, gassed to death, and their bodies burned in specially designed crematoriums. Approximately 3.5 million Jews were murdered in these death camps.
The Roma refer to the genocide of the Romani people as the Pořajmos.[414] Because they are traditionally a private people with a culture based on oral history, less is known about their experience than that of any other group.[415] Bauer writes that this can be attributed to the Roma's distrust and suspicion, and to their humiliation because some of the taboos in Romani culture regarding hygiene and sex were violated at Auschwitz.[416] In May 1942, the Roma were placed under similar laws to the Jews. On 16 December 1942, Himmler issued a decree that "Gypsy Mischlinge [mixed breeds], Roma Gypsies, and members of the clans of Balkan origins who are not of German blood" should be sent to Auschwitz, unless they had served in the Wehrmacht.[417] He adjusted the order on 15 November 1943; in the occupied Soviet areas, "sedentary Gypsies and part-Gypsies are to be treated as citizens of the country. Nomadic Gypsies and part-Gypsies are to be placed on the same level as Jews and placed in concentration camps."[418] Bauer argues that this adjustment reflected Nazi ideology that the Roma, originally an Aryan population, had been "spoiled" by non-Romani blood.[419]

The photo below shows Dr. Josef Mengele with Rudolf Hoess and Josef Kramer relaxing at Solahuette, the SS retreat near Birkenau. Kramer was the Commandant at Birkenau in 1944 when this photo was taken. In December 1944, he was transferred to Bergen-Belsen, which then became a concentration camp. The Bergen-Belsen camp had previously been a holding camp for Jews who were available for exchange with the Allies for German civilians held in British and American prisons. Hoess was the Commander of the SS garrison at Auschwitz in 1944.
It might be noted that, to a surprising extent, much about Hitler’s precise knowledge of the Holocaust remains unclear. For instance, we do not know if Hitler ever saw photographs or newsreels of the killing process, or, indeed, just how comprehensive and brutally frank were Himmler’s reports to Hitler. We have agendas of face-to-face meetings between Hitler and Himmler, at which the Holocaust was to be discussed, but no memorializations or minutes of such meetings. Most of the senior Nazis who were tried at Nuremberg in 1945-1946 (few of whom had any immediate involvement in the killing of Jews) had apparently never seen photographic evidence of the horrors of the concentration camps until their trials; they appeared to be genuinely shocked when newsreels of Belsen and Buchenwald were shown to the court.
Josef Mengele (/ˈmɛŋɡələ/; German: [ˈmɛŋələ]; 16 March 1911 – 7 February 1979) was a German Schutzstaffel (SS) officer and physician in Auschwitz concentration camp during World War II. He performed deadly human experiments on prisoners and was a member of the team of doctors who selected victims to be killed in the gas chambers. Arrivals that were judged able to work were admitted into the camp, while those deemed unsuitable for labor were sent to the gas chambers to be killed. With Red Army troops sweeping through Poland, Mengele was transferred 280 kilometers (170 mi) from Auschwitz to the Gross-Rosen concentration camp on 17 January 1945, just ten days before the arrival of the Soviet forces at Auschwitz. After the war, he fled to South America where he evaded capture for the rest of his life.