At the insistence of Joseph Stalin , the Yalta Conference sanctioned the formation of a new provisional pro-Communist coalition government in Moscow , which ignored the Polish government-in-exile based in London . This action angered many Poles who considered it a betrayal by the Allies . In 1944 , Stalin had made guarantees to Churchill and Roosevelt that he would maintain Poland 's sovereignty and allow democratic elections to take place . However , upon achieving victory in 1945 , the elections organized by the occupying Soviet authorities were falsified and were used to provide a veneer of legitimacy for Soviet hegemony over Polish affairs . The Soviet Union instituted a new communist government in Poland , analogous to much of the rest of the Eastern Bloc . As elsewhere in Communist Europe , the Soviet occupation of Poland met with armed resistance from the outset which continued into the Fifties
Yalta Conference
Yalta Conference
Poland