Attribution: By János Balázs from Berlin, Deutschland (memorial concentration camp Sachsenhausen) [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

…the train pulled up to another prison camp surrounded with barbed wire. A wrought iron sign at the gate stated “Arbeit Macht Frei.”

Liesel was dismayed. This again? She thought of Michal. His family had not been made free by work; she had not been made free by work. Freedom was only at the whim of the authorities and the only thing that would make her free was patience. Maybe.      (p. 343 Threaten to Undo Us)
During the late 1930’s and throughout the Second World War, millions of people, mostly Jews, lost their lives at the concentration camps of Auschwitz, Sachsenhausen, Potulice and other infamous locales. What is not so well known, is that after the war, a number of these camps were re-opened by the Office of State Security under the administration of  Polish communists. Ethnic Germans in Soviet-controlled Poland and other Eastern European countries were detained and mistreated in these camps, along with anyone remotely suspected of subversive activities against the new regime.

More  info: John Sacks,  An Eye for An Eye.

Alfred deZayas,  A Terrible Revenge.