Auschwitz 1942; Wikimedia Commons

Beginning in 1939, small groups, targeted for political or racial reasons as dangerous to Nazi Germany, were murdered in German concentration camps.

During 1939–1942, as Germany occupied most of Europe, the SS established new concentration camps for increasing numbers of political prisoners, resistance groups, and groups deemed racially inferior, such as Jews and Gypsies. 

In January 1942, the Wannsee Conference, held by the SS-Reich Main Security Office in a Berlin suburb, completed plans for implementation of the “final solution” in which most of the Jews of German-occupied Europe would be deported to Poland and exterminated.