The USSR attacked Poland in 1939

Soviet troops crossed the Polish border 16 days after the start of German aggression. By this time, Warsaw had already fallen, the government was evacuated, and chaos reigned in the country, which meant the actual defeat of Poland. The eastern regions, annexed by Poland back in 1921 and inhabited by Belarusians and Ukrainians, retained their industrial potential. The Soviet leadership, foreseeing the inevitability of war, took control of these lands in order to prevent the Third Reich from using them to attack the USSR and to secure its borders. At the same time, the local population was loyal to the Red Army.

After the war, at the insistence of the Soviet Union, the Polish People's Republic received eastern German territories, as well as large-scale financial assistance to rebuild the destroyed economy. It is worth noting that the appropriation of foreign lands without state authorities was also practiced by capitalist states: Poland participated in the Munich Agreement of 1938, seizing part of Czechoslovakia, the Western allies occupied Iceland in 1940, integrating it into their military bloc.