After 1942, the economic functions of the camps, previously secondary to their penal and terror functions, came to the fore. Forced labor of camp prisoners became commonplace. The guards became much more brutal, and the death rate increased as the guards not only beat and starved prisoners, but killed them more frequently. Vernichtung durch Arbeit ("extermination through labor") was a policy—camp inmates would literally be worked to death, or to physical exhaustion, at which point they would be gassed or shot. The Germans estimated the average prisoner's lifespan in a concentration camp at three months, due to lack of food and clothing, constant epidemics, and frequent punishments for the most minor transgressions. The shifts were long and often involved exposure to dangerous materials.
While the Nazis murdered other national and ethnic groups, such as a number of Soviet prisoners of war, Polish intellectuals, and gypsies, only the Jews were marked for systematic and total annihilation. Jews were singled out for "Special Treatment" (Sonderbehandlung), which meant that Jewish men, women and children were to be methodically killed with poisonous gas. In the exacting records kept at the Auschwitz death camp, the cause of death of Jews who had been gassed was indicated by "SB," the first letters of the two words that form the German term for "Special Treatment."
50,000 prisoners died in Bergen-Belsen. 60,000 prisoners were liberated by the Allies in April, 1945. The Bergen-Belsen staff, largely intact at the time of liberation, were tried in 1945 by a British military tribunal in Luneburg, Germany. Among those tried were the camp Kommandant, Josef Kramer, and a 22-year old female S.S. guard, Irma Grese, who was accused by camp inmates of shooting prisoners and beating them with a homemade whip. Forty-five staff were tried; fourteen were acquitted.
The Jews killed represented around one third of the world population of Jews, and about two-thirds of European Jewry, based on an estimate of 9.7 million Jews in Europe at the start of the war. Much of the uncertainty stems from the lack of a reliable figure for the number of Jews in Europe in 1939, numerous border changes that make avoiding double-counting of victims difficult, lack of accurate records from the perpetrators, and uncertainty about whether deaths occurring months after liberation, but caused by the persecution, should be counted.
The Nazis considered Jews to be the main danger to Germany. Jews were the primary victims of Nazi racism, but other victims included Roma (Gypsies) and people with mental or physical disabilities. The Nazis murdered some 200,000 Roma. And they murdered at least 250,000 mentally or physically disabled patients, mainly German and living in institutions, in the so-called Euthanasia Program.
On April 15, 1945, British troops entered Bergen Belsen. They liberated some 60,000 prisoners, many of whom were on the verge of death. During the first weeks after liberation, close to 500 people in Bergen Belsen died every day. From liberation day until June 20, an estimated 14,000 people died from the terrible conditions that had been inflicted on them by the Nazis during the war.
The workers who constructed the original buildings were housed in camps near Fallingbostel and Bergen, the latter being the so-called Bergen-Belsen Army Construction Camp. Once the military complex was completed in 1938/39, the workers' camp fell into disuse. However, after the German invasion of Poland in September 1939, the Wehrmacht began using the huts as a prisoner of war (POW) camp.