Before Auschwitz: Jewish Prisoners in the Prewar Concentration Camps. By Kim Wünschmann (Cambridge, Mass., Harvard University Press, 2015) 367 pp. $45.00

In the history of the Holocaust, the words Jews and camps are virtually coterminous. The wartime camps—from “pure” extermination facilities like Belzec to the complex Auschwitz–Birkenau–Monowitz system—allocated Jews from Germany and across Europe to either instant death or its ever-present threat. Historians have told this story repeatedly since 1945, even if new facets are always being identified. But the premise of Wünschmann’s impressive and deeply researched study is that the unfamiliar history of Jewish Germans in the very different circumstances of Germany’s concentration-camp system before the war has received far too little attention. Skeptics will attribute this lack of interest to the fact that the political logic of the concentration camps bypassed the incarceration of Jews, who were supposed to be driven into emigration, not detained for the purposes of “re-education.” As a result, the number of Jews in the camps was tiny—about 5 percent of the camps’ population, according...