During the 1939 German invasion of Poland, special action squads of SS and police (the Einsatzgruppen) were deployed in the rear, arresting or killing those civilians caught resisting the Germans or considered capable of doing so as determined by their position and social status. Tens of thousands of wealthy landowners, clergymen, and members of the intelligentsia—government officials, teachers, doctors, dentists, officers, journalists, and others (both Poles and Jews)—were either murdered in mass executions or sent to prisons and concentration camps. German army units and "self-defense" forces composed of Volksdeutsche also participated in executions of civilians. In many instances, these executions were reprisal actions that held entire communities collectively responsible for the killing of Germans.
During the summer of 1940, the SS rounded up members of the intelligentsia in the General Government. In this so-called A-B Aktion (Extraordinary Pacification Operation), several thousand university professors, teachers, priests, and others were shot. The mass murders occurred outside Warsaw, in the Kampinos forest near Palmiry, and inside the city at the Pawiak prison.
As part of wider efforts to destroy Polish culture, the Germans closed or destroyed universities, schools, museums, libraries, and scientific laboratories. They demolished hundreds of monuments to national heroes. To prevent the birth of a new generation of educated Poles, German officials decreed that Polish children's schooling end after a few years of elementary education. "The sole goal of this schooling is to teach them simple arithmetic, nothing above the number 500; writing one's name; and the doctrine that it is divine law to obey the Germans. . . . I do not think that reading is desirable," Himmler wrote in his May 1940 memorandum.
In the annexed lands, the Nazis' goal was complete "Germanization" to assimilate the territories politically, culturally, socially, and economically into the German Reich. They applied this policy most rigorously in western incorporated territories—the so-called Wartheland. There, the Germans closed even elementary schools where Polish was the language of instruction. They renamed streets and cities so that Lodz became Litzmannstadt, for example. They also seized tens of thousands of Polish enterprises, from large industrial firms to small shops, without payment to the owners. Signs posted in public places warned: "Entrance is forbidden to Poles, Jews, and dogs."
The Roman Catholic Church was suppressed throughout Poland because historically it had led Polish nationalist forces fighting for Poland's independence from outside domination. The Germans treated the Church most harshly in the annexed regions, as they systematically closed churches there; most priests were either killed, imprisoned, or deported to the General Government. The Germans also closed seminaries and convents, persecuting monks and nuns. Between 1939 and 1945 an estimated 3,000 members of the Polish clergy were killed; of these, 1,992 died in concentration camps, 787 of them at Dachau.