Concentration camps are prison camps for civilians incarcerated without due process. They were first created by the Spanish during the 1897 Cuban War of Independence. They were employed in subsequent years by the British (Boer War) and Americans (war against the Philippines).
Concentration camps made their first appearance in Europe with the 1918 Bolshevik revolution in Russia. While almost all inmates in the Soviet Union’s camp system had been convicted after “due process,” the trials were usually a mockery of justice, and in the case of political offenders, mere show trials.
The National-Socialist government in Germany, which to a considerable extent was a reaction against the Soviet Union’s attempt to expand their reign of terror, set up concentration camps right at the beginning of their rule, with the claim to squash a possible communist insurrection.
Already before National-Socialist rule, German law permitted the state to keep criminal offenders in prison even beyond a court-imposed prison term, if the public’s safety was at risk when releasing a usually hardened or repeat offender. That law exists to this day in Germany, but is now limited to severe felonies such as aggravated assault, rape and murder, and has many additional restrictions. This law could be applied more liberally in Germany’s past, which was (mis)used abundantly by the Third Reich’s police and SS authorities to keep dangerous criminals and political inmates incarcerated indefinitely. Camp admissions (without due process) increased over time, in particular during the war, and especially regarding the deportation of Jews.
In this encyclopedia, concentration camps are discussed only if any kind of extermination activity against Jews or against all inmates, irrespective of creed or ethnicity, has been claimed in them. This includes (see the respective entry, and also the entry on extermination camps):