At the end of and immediately after WWII, millions of ethnic Germans were cleansed from the eastern parts of Europe and sent to the areas which would become post-war Germany and post-war Austria, partly in retaliation for wartime cleansing by Nazi Germany. The areas of expulsion included pre-war German provinces as well as areas which Nazi Germany had annexed or occupied.
At least 12 million people - the overwhelming majority of whom were women, old people, and children under 16 - were expelled from their places of birth in Czechoslovakia, Hungary, Romania, Yugoslavia, and what are today the western districts of Poland. Those who survived the journey – about 500.000 did not – found themselves among the ruins of Allied-occupied Germany to fend for themselves as best they could.
This was the largest movement or transfer of any population in modern European history. A part of those fleeing did so “voluntarily”, in fear of the advancing Red Army. Others were forcefully expelled in an effort by the United States, Britain and the Soviet Union to redraw the European post-war map and to create ethnically uniform nations and territories. By 1950, the ordeal had ended.
Retaliation and “reparation” were the most commonly cited justifications for the expulsion; ethnic peace was another one: “defusing ethnic antagonisms through the mass transfer of populations”.
To make the horror complete,
tens of thousands perished as a result of ill treatment while being used as slave labor (or, in the Allies’ cynical formulation, “reparations in kind”) in a vast network of camps extending across central and southeastern Europe—many of which, like Auschwitz I and Theresienstadt, were former German concentration camps kept in operation for years after the war. (source)
A gruesome anecdote:
The screams that rang throughout the darkened cattle car crammed with deportees, as it jolted across the icy Polish countryside five nights before Christmas, were Dr. Loch’s only means of locating his patient. The doctor, formerly chief medical officer of a large urban hospital, now found himself clambering over piles of baggage, fellow passengers, and buckets used as toilets, only to find his path blocked by an old woman who ignored his request to move aside. On closer examination, he discovered that she had frozen to death.
Finally he located the source of the screams, a pregnant woman who had gone into premature labor and was hemorrhaging profusely. When he attempted to move her from where she lay into a more comfortable position, he found that “she was frozen to the floor with her own blood.” Other than temporarily stopping the bleeding, Loch was unable to do anything to help her, and he never learned whether she had lived or died. (source)