Further determinations regarding the future of Poland were made at the Yalta Conference in February 1945 . The United States and Britain accepted the Soviet position in respect to postwar borders ( the extent of Poland 's western expansion at the expense of Germany was not specified ) , but differed with the Soviets on the issue of participation of the London-based government-in-exile in the formation of Poland 's new compromise government . The Allied leaders ultimately authorized converting the existing in Poland , communist-dominated Provisional Government to Provisional Government of National Unity ( TRJN ) , with greater participation of democratic and pro-Western forces , but no formal role for the government-in-exile . The TRJN was charged with conducting free elections soon , based on which a permanent Polish government would be established . As for the practical implementation , a commission representing the three great powers negotiated the issue of the TRJN in Moscow and the talks had been stalled for a long time , until joined by former Prime Minister Mikołajczyk of the government-in-exile . In June Mikołajczyk agreed to a temporary deal , which turned out to permanently favor the communist side
Yalta Conference
Yalta Conference
Polish Workers' Party