The rise of Communism in Poland after WWII followed Soviet occupation and the increase in authority of Poland’s Communist Party. While other political parties vied for power, it was the Communists who established a new government with help from Stalin and the USSR in the mid 1940s.
Communism’s rise began with the Soviet occupation of Poland during WWII. Stalin had, through the Molotov-Ribbentrop pact, divided up Polish territory with Hitler so that Germany and the USSR would each get a piece of Poland. When Germany invaded Poland in 1939, the USSR waited until the Polish military had reached defeat before taking up position in its allotted territory. During and after the war, the USSR worked behind the scenes to secure a political foothold in Poland during its occupancy.
In 1942-43, the USSR began a series of tactics to intimidate or Poland’s government. Stalin first exhibited unwillingness to cooperate with Poland’s acting government. The Polish embassy in the USSR was repressed. Citizens of former Polish lands that were absorbed into the USSR upon border re-negotiations were refused permission to return to Poland. The Polish government, which maintained its status in exile in London during the war, struggled to sustain diplomatic relations with the USSR.
The Polish government-in-exile began to question the disappearance of thousands of Polish military officers. During the Katyn Massacre of 1940, the officers had been executed by Soviet troops (the graves had later been discovered by German troops). When the Polish government sought to investigate the matter, this was the excuse Stalin needed to cut off diplomatic relations.
Stalin manipulated the situation, indicating publicly that he was interested in seeing an independent Poland established. Stalin also stated that he would only resume diplomatic relations with Poland once the government was restructured according to the will of its people. While some officials may have taken these statements at face value, they were effectively part of a stall tactic to give Communist political parties time to organize.
Polish Communists prepared for the formation of a new government by organizing the Polish National Committee in Moscow. The plans made by this committee included the creation of a government that appeared, from the outside, to be multi-party and a coalition, when in reality it would be monopolized by Communists with support from the USSR.
A group called the National Council for the Homeland (KRN), a Communist organization, supplanted the Polish National Committee. The KRN made a journey to Moscow in 1944, and after some back-and-fourth, Stalin indicated that a new government for Poland should be created out of the KRN and acknowledged its authority. This created a gateway for Communists,who were closely tied to policies of the USSR, to take power in Poland.