The Allies had no intention of allowing Sikorski 's successor , Stanisław Mikołajczyk , to threaten the alliance with the Soviets . No representative of the Polish government was invited to the Tehran Conference ( 28 November – 1 December 1943 ) or the Yalta Conference ( 4 – 11 February 1945 ) , the two crucial events in which the Western Allies and the Soviet Union discussed the shape of the post-war world and decided on the fate of Poland . Only four months after Sikorski 's death , in November 1943 , at Tehran , Churchill and Roosevelt agreed with Stalin that the whole of Poland east of the Curzon Line would be ceded to the Soviets . In Teheran , neither Churchill nor Roosevelt objected to Stalin 's suggestion that the Polish government in exile in London was not representing Polish interests ; as historian Anita Prażmowska noted , " this spelled the end of that government 's tenuous influence and raison d'être . " After the Teheran Conference , Stalin decided to create his own puppet government for Poland , and a Committee of National Liberation ( PKWN ) was proclaimed in the summer of 1944 . The Committee was recognized by the Soviet Government as the only legitimate authority in Poland , while Mikołajczyk 's Government in London , was termed by the Soviets an " illegal and self-styled authority . " Mikołajczyk would serve in the Prime Minister 's role until 24 November 1944 , when , realizing the increasing powerlessness of the government in exile , he resigned and was succeeded by Tomasz Arciszewski , " whose obscurity " , in the words of historian Mieczysław B. Biskupski , " signaled the arrival of the government in exile at total inconsequentiality . " Stalin soon began a campaign for recognition by the Western Allies of a Soviet-backed Polish government led by Wanda Wasilewska , a dedicated communist with a seat in the Supreme Soviet , with General Zygmunt Berling , commander of the 1st Polish Army in Russia , as commander-in-chief of all Polish armed forces . By the time of the Potsdam conference in 1945 , Poland has been relegated to the Soviet sphere of influence ; an abandonment of the Polish government in exile that has led to the rise of the Western betrayal concept
Yalta Conference
Yalta Conference
Władysław Sikorski