 Complete the following phrase:  Adolf Hitler believed that the Polish elites might inspire the Poles to disobey their new German masters so he decreed that they had to be eliminated beforehand. The aim was the elimination of Polish societys elite, which was very broadly defined as: Polish nobles, intelligentsia, teachers, entrepreneurs, social workers, military veterans, members of national organizations, priests, judges, political activists, and anyone who had attended secondary school. It was continued by the German AB-Aktion operation in Poland in the spring and summer of 1940, which saw the massacre of Lwów professors and the execution of about 1,700 Poles in the Palmiry forest. Several thousand civilians were executed or imprisoned. The Einsatzgruppen were also responsible for the indiscriminate killing of Poles during the 1941 German invasion of the Soviet Union which 