The PKWN was formed in negotiations involving primarily the main Polish communist organizations , the Union of Polish Patriots ( ZPP ) and the Polish Workers ' Party ( PPR ) . The Polish communist movement had been decimated during the Soviet purges in the 1930s , but revived under Stalin 's auspices beginning in 1940 . The PPR was a new party organized in occupied Poland , the ZPP originated during the war in the Soviet Union . The PPR had already established in Warsaw a conspiratorial State National Council ( KRN ) , which they declared to be the wartime national parliament . Because of war-related obstacles , the communist leaders arriving from Warsaw ( the PPR delegation that included Władysław Gomułka and Bolesław Bierut ) reached Lublin only on 31 July , and attained full agreement with the group from Moscow ( ZPP ) on 15 August . The documents they produced were antedated to 21 July to comply with the declarations issued as of 22 July
Soviet purges
Great Purge
Polish Committee of National Liberation