In the popular imagination, the Nazi concentration camp now features mainly as a place where Jews were taken to be gassed. In a recent German opinion poll, most respondents associated the camps with the persecution and murder of Jews; under 10 percent mentioned other categories of camp prisoners, such as Communists, criminals, or homosexuals. The power of the “Holocaust” as a concept has all but obliterated other aspects of the crimes of the Nazis and the sufferings of their victims and driven the history of the camps from cultural memory. No crime in human history outdoes the genocidal extermination of six million European Jews on the orders of the leader of Germany’s self-styled “Third Reich.” Yet the majority of the Jewish victims of Nazi mass murder were not killed in the camps; they were shot, starved to death, or left to die of diseases that could easily have been prevented or treated but were not. The concentration camp was in no way synonymous with the Holocaust.

While facilities such as Treblinka or Auschwitz-Birkenau, constructed for no other purpose than mass murder, were first established during World War II, the history of the concentration camp, as Nikolaus Wachsmann reminds us in his impressive and authoritative new study, begins much earlier. The idea of concentrating a state’s enemies in a camp went back at least to the end of the nineteenth century, following the invention of barbed wire and the machine gun, in the Boer War and the Spanish-American War, and found expression in the Soviet system of labor camps and other products of twentieth-century dictatorships. But these camps neither formed the template for the Nazi concentration camps nor resembled them in all respects, even if they were similar in some. Ninety percent of inmates survived the Soviet Gulag, for example, while in the wartime camps of the SS, even for prisoners who were registered as inmates and not killed immediately on arrival, the survival rate was less than half. Of some 2.3 million men, women, and children who were put into Nazi concentration camps between 1933 and 1945, more than 1.7 million lost their lives, almost a million of them Jews killed in Auschwitz.

Wachsmann’s gripping, humane, and beautifully written narrative begins with the establishment of the first of the Nazi camps, at a disused munitions factory outside the town of Dachau, near Munich. During the first half of 1933, as Hitler gathered the reins of power to himself, makeshift camps were improvised all over Germany to incarcerate Communists and Social Democrats, the main political groups who resisted the Nazis’ violent seizure of power. Only gradually were these closed down, with the release of the prisoners, many of whom had been badly beaten and tortured (even the official estimate reckoned that over six hundred were murdered by the Nazis), on promise of refraining from political engagement. By 1934, as Wachsmann showed in his previous book, Hitler’s Prisons (2004), the function of political repression had been taken over by the police, the courts, and the regular state prisons and penitentiaries.

The remaining concentration camps, which held fewer than four thousand inmates by 1935, then became the dumping grounds for “asocials,” alcoholics, vagrants, and social deviants. By 1939 there were six such camps, at Ravensbrück, Sachsenhausen, Dachau, Flossenbürg, and Buchenwald in the “old Reich” and Mauthausen in the annexed territory of Austria. During the war, however, as the German economy experienced a rapidly growing labor shortage, with millions of men at the front and millions of women staying at home in obedience to the Nazi image of women as mothers and homemakers, supported by generous subsidies to enable them to do so, the camps were transformed into centers of forced labor, buttressed by the industrial sub-camps that spread like a cancer through the body of the German Reich. ...