For the next five years, Poland endured the most severe wartime occupation conditions in modern European history. Initially, Germany annexed western Poland directly, establishing a brutal colonial government whose expressed goal was to erase completely the concept of Polish nationhood and make the Poles slaves of a new German empire. About 1 million Poles were removed from German-occupied areas and replaced with German settlers. An additional 2.5 million Poles went into forced labor camps in Germany.

Until mid-1941, Germany and the Soviet Union maintained good relations in the joint dominion they had established over Poland. Moscow had absorbed the eastern regions largely inhabited by Ukrainians and Belorussians. By 1941 the Soviets had moved 1.5 million Poles into labor camps all over the Soviet Union, and Stalin's secret police had murdered thousands of Polish prisoners of war, especially figures in politics and public administration. The most notorious incident was the 1940 murder of thousands of Polish military officers the bodies of 4,000 of them were discovered in a mass grave in the Katyn forests near Smolensk in 1943. Because Soviet authorities refused to admit responsibility until nearly the end of the Soviet Union in 1991, Polish opinion regarded the Katyn Massacre as the ultimate symbol of Soviet cruelty and mendacity (see Soviet Union and Russia , ch. 4).

After Germany invaded the Soviet Union in June 1941, all the Polish lands came under control of the Third Reich, whose occupation policies became even more bloodthirsty as the war continued (see fig. 10). Hitler considered Poland to be an integral part of German Lebensraum, his concept of German domination of the European continent. Eastern Europe would be purged of its population of putative racial inferiors and prepared as the hinterland of a grandiose Germanic empire. This vision fueled the genocidal fanaticism of the conquerors. Reduced to slave status, the Poles lived under severe restrictions enforced with savage punishment. As the principal center of European Jewry, Poland became the main killing ground of the Nazi Holocaust several of the most lethal death camps, including Auschwitz, Majdanek, and Treblinka, operated on Polish soil. The Germans annihilated nearly all of Poland's 3 million Jews. Roughly as many Polish gentiles also perished under the occupation.

Data as of October 1992