In the aftermath of the joint German-Soviet invasion of Poland , the Polish government evacuated to the West and created the Polish Underground State . While no war was declared between Poland and the Soviet Union , the relations were tense , and eventually broke down in 1943 in the aftermath of the revelations of the Katyn massacre . The Soviets eventually created their own Polish communist puppet government , the Polish Committee of National Liberation ( '' Polski Komitet Wyzwolenia Narodowego '' , '' PKWN '' ) and refused to deal with the Underground State just like they refused to deal with the government-in-exile ; its leaders and soldiers on " liberated " Polish territories were persecuted . While the Underground State 's military arm , '' Armia Krajowa '' , officially disbanded on January 19 , 1945 to avoid armed conflict with the Soviets and a civil war , some refused to lay down their arms ; others found it simply difficult to return to civilian life , as those with ties to non-communist resistance were discriminated against by the authorities
Katyn massacre
Katyn massacre
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