Nazis constructed gas chambers (rooms that filled with poison gas to kill those inside) to increase killing efficiency and to make the process more impersonal for the perpetrators. At the Auschwitz camp complex, the Birkenau killing center had four gas chambers. During the height of deportations to the camp in 1943-44, an average of 6,000 Jews were gassed there each day.
According to the numbers provided by the US Holocaust Memorial Museum, Auschwitz was the site of the most deaths (1.1 million) of any of the six dedicated extermination camps. By these estimates, Auschwitz was the site of at least one out of every six deaths during the Holocaust. The only camp with comparable figures was Treblinka in north-east Poland, where about 850,000 are thought to have died.
With its sections separated by barbed-wire fences, Auschwitz II had the largest prisoner population of any of the three main camps. In January 1942, the first chamber using lethal Zyklon B gas was built on the camp. This building was judged inadequate for killing on the scale the Nazis wanted, and four further chambers were built. These were used for systematic genocide right up until November 1944, two months before the camp was liberated.
The arrests took place in various ways, partly through the S.A. or S.S., partly through uniformed police, partly through plain-clothes men or secret police. It was the latter in my case. There appeared suddenly at our door a group of three men in civilian clothes, identified by their badges as policemen, who took us away in a car after having established through questioning that we were 'non-Aryans.' They also arrested a gentleman who happened to be visiting us. They had no warrants, and declined to give any information about our further destiny; our families for days were without any idea of what had happened to us. We were brought into the courtyard of the police headquarters, our names and addresses were taken down, and without any further hearing we were loaded into large trucks covered with canvas, in which benches had been placed. For the older people—and the majority were over fifty—a chair had been provided so that they might climb into the truck more easily. We mention this here especially because the treatment of the uniformed police in charge of the transportation differed pleasantly from the treatment we suffered in the camp at the hands of the S.S. The crowds in the streets took little notice of the police trucks driving in a row. Only a few urchins around the police headquarters greeted us with howling.
Use of the word "concentration" came from the idea of confining people in one place because they belong to a group that is considered undesirable in some way. The term itself originated in 1897 when the "reconcentration camps" were set up in Cuba by General Valeriano Weyler. In the past, the U.S. government had used concentration camps against Native Americans and the British had also used them during the Second Boer War. Between 1904 and 1908, the Schutztruppe of the Imperial German Army operated concentration camps in German South-West Africa (now Namibia) as part of its genocide of the Herero and Namaqua peoples. The Shark Island Concentration Camp in Lüderitz was the largest camp and the one with the harshest conditions.