The casual reader should receive the message that the expulsions were agreed to at the Yalta and Potsdam conferences  They should also be aware that Stalin outmaneuvered the gullible Western Allies at both those conferences  Stalin didnt care about the Poles he killed  Poles mostly Polish military officers at Katyn in  Stalin was more concerned about gaining back lands lost in the early s namely lands within the  Polish border east of the Curzon Line  That land area had a population which included  ethnic Poles  Stalin needed somewhere to dump those Poles so he proposed that Germans be moved west  the Poles be moved west  Roosevelt was dying in   he was easily outmaneuvered by Stalin  By the Potsdam Conference in the summer of  Churchill had lost power and had to leave the conference early and Truman was tied down by Roosevelts commitments so Stalin got his way again   The casual reader should also receive the message that the Wild expulsions by both Russian and Polish authorities were begun east of the OderNeisse Line and long before the end of July  Potsdam Conference which ONLY authorized the ethnic cleansing of Germans from within the  borders of Poland and from Czechoslovakia and Hungary  The Potsdam Agreement separated all German territory east of the OderNeisse Line from Occupation Germany all of that German territory east of the OderNeisse Line had been part of the Soviet Occupation Zone of Germany prior to the Potsdam Conference  Most of that German territory was placed under temporary Polish Administration pending the final Peace Treaty for World War   The Potsdam Agreement also stipulated that Northern East Prussia to be  placed under temporary Soviet Administration pending the final Peace Treaty for World War   Note there is a distinction between Occupation and temporary Adminsitration as delineated by the Potsdam Agreement