Soviet occupied Poland
Poland would be ‘liberated’ by the Soviets in World War II. Poland was under a Soviet-styled government for over forty years.
World War II
Poland was occupied by Nazi Germany since the invasion in 1939, resistance fought the occupying Germans until the Soviets liberated the country in 1945 and set up the provisional government of the Republic of Poland.
Post World War II
the Polish People's Republic was set up after the war ended, it was a puppet regime set up by the occupying Soviets, rebellions happened all were crushed, in 1955, after West Germany joined NATO, the Warsaw Pact was formed and Poland joined it.
In the 1980s, the USSR was losing the Cold War and the Warsaw pact countries gained independence from the pact, including Poland which brought back the Polish government-in-exile, which had been in exile since 1939.
Maps
Map of Poland pre World War II
Map of Poland post World War II