CONCENTRATION CAMPS (Ger. Konzentrationslager - KZ) 
 
 Camps in which persons are imprisoned without regard to the accepted norms of arrest and detention. Although the term "concentration camp" is sometimes used as a generic term for Nazi camps, not all the camps eventually established by the Nazis were designated as concentration camps proper. The extensive Nazi camp system also included labour camps (Arbeitslager), transit camps (Durchgangslager), prisoner-of-war (POW) camps (Kriegsgefangenlager), and extermination camps (Vernichtungslager). This entry focuses on the network of concentration camps. 
 
 A Tool of Oppression 
 Concentration camps were an essential part of the Nazi regime of oppression. The regime imprisoned in such camps political adversaries and persons considered socially or racially undesirable. Forced labour performed by the prisoners became a central element of the imprisonment. During World War II, the concentration camps also played a part in the Nazi fight against the resistance movements, and some camps (such as Auschwitz and Majdanek) were centres for the systematic extermination of Jews, Gypsies, Soviet prisoners of war (POWs) and other groups in the Reich and occupied territories. The history of the concentration camps can be divided into three periods: (1) 1933-1936; (2) 1936-to 1942; and (3) 1942-1945. 
 During the first period, when the Nazis still had to consolidate their power, the concentration camps were established mainly as an apparatus of political oppression. Thus, in Dachau, opened in March 1933 as the first NS concentration camp, mainly political opponents were detained. In fall 1933, the Nazis began to take in "protective custody" (SCHUTZHAFT) also persons whom they considered as "asocial elements", such as beggars, tramps, and criminals. 
 In the second period, nearly all of the concentration camps, which had been established to break the opposition to the Nazi regime, were shut down (except Dachau) and replaced by new, larger camps corresponding to the rapidly growing number of prisoners. Those camps, including Sachsenhausen, Buchenwald, Mauthausen, Flossenburg, Ravensbrueck, Auschwitz, Stutthof, Majdanek, and Neuengamme, served the Nazis as a crucial instrument of racial persecution. From 1937 on, German companies used Jews for forced labor, housing them in camps. After the Novemberpogrom in 1938 ("Crystal Night"), 36.000 Jews were imprisoned in camps just for being Jews. The number of prisoners (beside of Jews also Gypsies, homosexuals, Jehovah's witnesses, from June 1941 on also Soviet Prisoners of War) rose constantly. 
 In the early year of 1942, prisoners were officially exploited as forced laborers in the German armaments industry. Their productivity was overseen and controlled by the Economic-Administrative Main Office (WIRTSCHAFTS-VERWALTUNGSHAUPTAMT, WVHA), established in 1942 by the SS. All over the German Reich a lot of small satellite camps were built next to industrial factories in order to house the forced laborers. The number of prisoners rose to about 525.000 in august 1944 and to more than 600.000 at the beginning of 1945. 
 Most of the camps were administrated and guarded by SS. There was also set up a hierarchy among the prisoners, headed by the camp elder (LAGERAELTESTER), followed by block- or room elder (BLOCKAELTESTER, STUBENAELTESTER), who held a supervisory or administrative position. Criminal or political prisoners often were appointed as work foremen (KAPOS). 
 The treatment of prisoners varied during the three periods and from camp to camp. Living conditions were more bearable during the first period (1933-36) and deteriorated dramatically in the following years, when many camp inmates died of malnutrition, inhuman work- and housing conditions and because of brutal treatment. Although the unauthorized mistreatment and killing of prisoners was officially forbidden, beating, hanging, drowning of prisoners by the camp's SS personnel as well as lethal torture occurred as a part of daily routine in most of the camps.