German occupation forces began a policy of repression against the Polish population of eastern Upper Silesia , which started as early as September 1939 based on lists made before the war that pointed out Poles active in social and political life . A second wave of arrests happened during October and November in '' Intelligenzaktion Schlesien '' , aimed against Polish intellectuals , many of whom perished in prison camps . A third wave of arrests came in April and May 1940 during the AB Aktion
Intelligenzaktion
Intelligenzaktion
Province of Upper Silesia