Political dissidents, trade unionists, and Social Democrats were among the first to be arrested and incarcerated in concentration camps. Under the Weimar government, centuries-old prohibitions against homosexuality had been overlooked, but this tolerance ended violently when the SA (Storm Troopers) began raiding gay bars in 1933. Homosexual intent became just cause for prosecution. The Nazis arrested German and Austrian male homosexuals—there was no systematic persecution of lesbians—and interned them in concentration camps, where they were forced to wear special yellow armbands and later pink triangles. The goal of persecuting male homosexuals was either for reeducation—what might now be called conversion therapy—or punishment. Jehovah’s Witnesses were a problem for the Nazis because they refused to swear allegiance to the state, register for the draft, or utter the words “Heil Hitler.” As a result, the Nazis imprisoned many of the roughly 20,000 Jehovah’s Witnesses in Germany. They could be released from concentration camps if they signed a document renouncing their faith and promising not to proselytize. Few availed themselves of that option, preferring martyrdom to apostasy. Germans of African descent—many of whom, called “Rhineland bastards” by the Nazis, were the offspring of German mothers and French colonial African troops who had occupied the Rhineland after World War I—were also persecuted by the Nazis. Although their victimization was less systematic, it included forced sterilization and, often, internment in concentration camps. The fear was that they would “further pollute” and thereby diminish the race. The Nazis also singled out the Roma and Sinti, pejoratively known as Gypsies. They were the only other group that the Nazis systematically killed in gas chambers alongside the Jews. For the Roma and Sinti, too, racial pollution and their depiction as asocials was the justification for their persecution and murder.
Of a total of 2,720 clergy recorded as imprisoned at Dachau, the overwhelming majority, some 2,579 (or 94.88%) were Catholic. Among the other denominations, there were 109 Protestants, 22 Greek Orthodox, 8 Old Catholics and Mariavites and 2 Muslims. In his Dachau: The Official History 1933–1945, Paul Berben noted that R. Schnabel's 1966 investigation, Die Frommen in der Hölle ("The Pious Ones in Hell") found an alternative total of 2,771 and included the fate all the clergy listed, with 692 noted as deceased and 336 sent out on "invalid trainloads" and therefore presumed dead.[58]:276–277 Over 400 German priests were sent to Dachau.[59] Total numbers incarcerated are nonetheless difficult to assert, for some clergy were not recognised as such by the camp authorities, and some—particularly Poles—did not wish to be identified as such, fearing they would be mistreated.[58]:157

The name Dachau became a household word for Americans following World War II. This was because it was the only major Nazi concentration camp in the American occupation zone in western Germany. Bergen-Belsen was in the British zone of occupation and Natzweiler was in the French zone. Buchenwald and Sachsenhausen were in the Soviet zone of occupation in eastern Germany and Mauthausen was in the Soviet zone of Austria.

Soviet civilian populations in the occupied areas were heavily persecuted.[438] Villages throughout the Soviet Union were destroyed by German troops.[439] Germans rounded up civilians for forced labor in Germany and caused famine by taking foodstuffs.[440] In Belarus, Germany imposed a regime that deported some 380,000 people for slave labor and killed hundreds of thousands of civilians. Over 600 villages had their entire populations killed, and at least 5,295 Belarusian settlements were destroyed by the Germans. According to Timothy Snyder, of "the nine million people who were in the territory of Soviet Belarus in 1941, some 1.6 million were killed by the Germans in actions away from battlefields, including about 700,000 prisoners of war, 500,000 Jews, and 320,000 people counted as partisans (the vast majority of whom were unarmed civilians)".[441] The United States Holocaust Memorial Museum has estimated that 3.3 million of 5.7 million Soviet POWs died in German custody.[442] The death rates decreased as the POWs were needed to help the German war effort; by 1943, half a million had been deployed as slave labor.[409]
The camp physician, Dr. Katz of Nuremberg, was also a prisoner. At first he was well treated because the guards and even the Commander admired his courageous attitude, but after he had witnessed the torture inflicted upon the prisoners, it became dangerous for the Nazis to release him. It was reported later that he had hanged himself in a detention cell—a few days before his anticipated release. His presence in the cell, however, was never explained.
^ Jump up to: a b Zamecnick, Stanislas (2013). C'était ça, Dachau: 1933–1945 [This was Dachau: 1933–1945] (in French). Paris, France: Cherche midi. ISBN 9782749132969., page 71: 2,903 deaths from typhus in January 1945, 3,991 in February, 3,534 in March, 2,168 in April before the liberation. 14,511 registered typhus deaths since it began to spread in October 1944.
Near the end of the movie Schindler’s List, a famous scene depicts Oskar Schindler departing his factory at the end of the war and crying without consolation over his inability to save even more lives. (The scene was even parodied in an episode of Seinfeld.) “The idea that Oskar collapsed sobbing into Itzhak Stern’s arms and bemoaned his failure to save more Jews is preposterous,” writes Crowe. “Oskar was proud of all he had done to save Brunnlitz’s Jews and said so in his speech earlier that evening.”
Dachau prisoners were used as forced laborers. At first, they were employed in the operation of the camp, in various construction projects, and in small handicraft industries established in the camp. Prisoners built roads, worked in gravel pits, and drained marshes. During the war, forced labor utilizing concentration camp prisoners became increasingly important to German armaments production.
In early 1942 the Nazis built killing centres at Treblinka, Sobibor, and Belzec in occupied Poland. The death camps were to be the essential instrument of the “final solution.” The Einsatzgruppen had traveled to kill their victims. With the killing centres, the process was reversed. The victims were taken by train, often in cattle cars, to their killers. The extermination camps became factories producing corpses, effectively and efficiently, at minimal physical and psychological cost to German personnel. Assisted by Ukrainian and Latvian collaborators and prisoners of war, a few Germans could kill tens of thousands of prisoners each month. At Chelmno, the first of the extermination camps, the Nazis used mobile gas vans. Elsewhere they built permanent gas chambers linked to the crematoria where bodies were burned. Carbon monoxide was the gas of choice at most camps. Zyklon-B, an especially lethal killing agent, was employed primarily at Auschwitz and later at Majdanek.

During the first three weeks the camp was under the command of the regular police fore. Then the Nazis appeared one night to take over control. Their leader made a speech to his followers, of which the following quotations are of interest: “Always remember that no human beings are here, only swine.”—“Whoever does not wish to see blood may go home immediately.”—“No one who does harm to a prisoner need fear reprimand.”—“The more you shoot, the fewer we must feed.”
In April 1943, the SS took over the southern section of the camp and turned it into an “exchange camp” for Jewish prisoners. The SS decided in the spring of 1944 to also use the camp for other purposes and additional groups of prisoners. This dramatically changed the character of the camp, the structure of the prisoner society and, above all, the prisoners’ living conditions. When the Bergen-Belsen concentration camp was liberated on 15 April 1945, British soldiers found thousands of unburied bodies and tens of thousands of severely ill prisoners.
In the view of Christian Gerlach, Hitler announced his decision to annihilate the Jews on or around 12 December 1941, probably on 12 December during a speech to the Gauleiters, part of the Nazi Party leadership.[259] This was one day after the German declaration of war against the United States, which followed the Japanese attack on Pearl Harbour on 7 December and the United States declaration of war on Japan on 8 December.[260] According to Deborah Dwork and Robert Jan van Pelt, Hitler had trusted American Jews, whom he assumed were all-powerful, to keep their government out of the war in the interests of German Jews. When America declared war, the Jews were blamed.[261] Joseph Goebbels, the Reich Minister of Propaganda, noted of Hitler's speech: "He warned the Jews that if they were to cause another world war, it would lead to their destruction. ... Now the world war has come. The destruction of the Jews must be its necessary consequence."[260][o]
By March 9, 1945, a total of 28,838 prisoners had been brought to Dachau and then transferred to the 11 Landsberg sub-camps. Approximately 14,500 prisoners died in these camps. In April 1945, the Kaufering camps were evacuated, except for the Kaufering IV camp where sick prisoners were left behind. Kaufering IV was liberated by American soldiers two days before the main camp was liberated.
A young man sits on an overturned stool next to a burnt body in the Thekla camp outside Leipzig, in April of 1945, after the US troops entered Leipzig April 18. On the 18th of April, the workers of the Thekla plane factory were locked in an isolated building of the factory by the Germans and burned alive by incendiary bombs. About 300 prisoners died. Those who managed to escape died on the barbed wire or were executed by the Hitler youth movement, according to a US captain's report. #
Former concentration camp inmates of Dachau and Displaced Persons from other camps were housed at the Dachau army garrison, next door to the concentration camp; they were fed by the American Army. Former inmates were paid to be prosecution witnesses in a series of American Military Tribunals that were held on the grounds of the Dachau complex, beginning in November 1945.
Moshe Peer has spent many years writing a first-person account of the horror he witnessed at Bergen-Belsen. He recalls the separation from his parents as excruciating. But surviving the horrors of the camp quickly became a priority: `There were pieces of corpses lying around and there were bodies lying there, some alive and some dead,` Peer recalled,  `Bergen-Belsen was worse than Auschwitz because there people were gassed right away so they didn't suffer a long time ...` Russian prisoners were kept in an open-air camp and were given no food or water. `Some people went mad with hunger and turned to cannibalism.`
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.
Außenlager Unterlüß-Altensothrieth (Tannenberglager) east of Bergen was in use from late August 1944 to April 13, 1945. It was located at Unterlüß, where the Rheinmetall-Borsig AG had a large test site. Up to 900 female Polish, Hungarian, Romanian, Yugoslavian and Czech Jews had to clear forest, do construction work or work in munitions production.[10]:204