Behind The Frontline
Many refugees tried to return home when the fighting in their homelands ended. Before June 1, 1945, some 400,000 crossed back over the Oder and Neisse rivers eastward, before Soviet and Polish communist authorities closed the river crossings; another 800,000 entered Silesia from Czechoslovakia.
Soviet troops, as well as Polish civilians and militias exacted revenge on ethnic Germans and German nationals after years of German state's and its supporters attempts of genocide, slavery and numerous atrocities against Polish and Soviet people's. While many Germans had already fled ahead of the advancing Soviet Army, millions of Reichs- and Volksdeutsche remained in East and West Prussia, Silesia, Pomerania, the Sudetenland, and in pockets throughout Central and Eastern Europe. The Polish courier Jan Karski warned US President Franklin Delano Roosevelt of the possibility of Polish reprisals, describing them as "unavoidable" and "an encouragement for all the Germans in Poland to go west, to Germany proper, where they belong".
Read more about this topic: Flight And Expulsion Of Germans From Poland During And After World War II