Flight and expulsion of Germans (1944–1950)

During the later stages of World War II and the post-war period, Reichsdeutsche (German citizens) and Volksdeutsche (ethnic Germans living outside the Nazi state) fled and were expelled from various Eastern and Central European countries, including Czechoslovakia, and from the former German provinces of Lower and Upper Silesia, East Prussia, and the eastern parts of Brandenburg (Neumark) and Pomerania (Farther Pomerania), which were annexed by the Provisional Government of National Unity of Poland and by the Soviet Union.

The idea to expel the Germans from the annexed territories had been proposed by Winston Churchill, in conjunction with the Polish and Czechoslovak governments-in-exile in London since at least 1942. Tomasz Arciszewski, the Polish prime minister in-exile, supported the annexation of German territory but opposed the idea of expulsion, wanting instead to naturalize the Germans as Polish citizens and to assimilate them. Joseph Stalin, in concert with other Communist leaders, planned to expel all ethnic Germans from east of the Oder and from lands which from May 1945 fell inside the Soviet occupation zones.^{[citation needed]} In 1941, his government had already transported Germans from Crimea to Central Asia.

Between 1944 and 1948, millions of people, including ethnic Germans (Volksdeutsche) and German citizens (Reichsdeutsche), were permanently or temporarily moved from Central and Eastern Europe. By 1950, about 12 million Germans had fled or been expelled from east-central Europe into Allied-occupied Germany and Austria. The West German government put the total at 14.6 million, including a million ethnic Germans who had settled in territories conquered by Nazi Germany during World War II, ethnic German migrants to Germany after 1950, and the children born to expelled parents. The largest numbers came from former eastern territories of Germany ceded to the Polish People's Republic and Soviet Union (about seven million), and from Czechoslovakia (about three million).

The areas affected included the former eastern territories of Germany, which were annexed by Poland, as well as the Soviet Union after the war and Germans who were living within the borders of the pre-war Second Polish Republic, Czechoslovakia, Hungary, Romania, Yugoslavia, and the Baltic states. The death toll attributable to the flight and expulsions is disputed, with estimates ranging from 500,000 up to 2.5 million according to the German government.

The removals occurred in three overlapping phases, the first of which was the organized evacuation of ethnic Germans by the Nazi state in the face of the advancing Red Army from mid-1944 to early 1945. The second phase was the disorganised flight of ethnic Germans immediately following the Wehrmacht's surrender. The third phase was a more organised expulsion following the Allied leaders' Potsdam Agreement, which redefined the Central European borders and approved expulsions of ethnic Germans from the former German territories transferred to Poland, Russia, and Czechoslovakia. Many German civilians were sent to internment and labour camps where they were used as forced labour as part of German reparations to countries in Eastern Europe. The major expulsions were completed in 1950. Estimates for the total number of people of German ancestry still living in Central and Eastern Europe in 1950 ranged from 700,000 to 2.7 million.

Before World War II, East-Central Europe generally lacked clearly delineated ethnic settlement areas. There were some ethnic-majority areas, but there were also vast mixed areas and abundant smaller pockets settled by various ethnicities. Within these areas of diversity, including the major cities of Central and Eastern Europe, people in various ethnic groups had interacted every day for centuries, while not always harmoniously, on every civic and economic level.

With the rise of nationalism in the 19th century, the ethnicity of citizens became an issue in territorial claims, the self-perception/identity of states, and claims of ethnic superiority. The German Empire introduced the idea of ethnicity-based settlement in an attempt to ensure its territorial integrity. It was also the first modern European state to propose population transfers as a means of solving "nationality conflicts", intending the removal of Poles and Jews from the projected post–World War I "Polish Border Strip" and its resettlement with Christian ethnic Germans.

Following the collapse of Austria-Hungary, the Russian Empire, and the German Empire at the end of World War I, the Treaty of Versailles pronounced the formation of several independent states in Central and Eastern Europe, in territories previously controlled by these imperial powers. None of the new states were ethnically homogeneous. After 1919, many ethnic Germans emigrated from the former imperial lands back to the Weimar Republic and the First Austrian Republic after losing their privileged status in those foreign lands, where they had maintained minority communities. In 1919 ethnic Germans became national minorities in Poland, Czechoslovakia, Hungary, Yugoslavia, and Romania. In the following years, the Nazi ideology encouraged them to demand local autonomy. In Germany during the 1930s, Nazi propaganda claimed that Germans elsewhere were subject to persecution. Nazi supporters throughout eastern Europe (Czechoslovakia's Konrad Henlein, Poland's Deutscher Volksverband and Jungdeutsche Partei, Hungary's Volksbund der Deutschen in Ungarn) formed local Nazi political parties sponsored financially by the German Ministry of Foreign Affairs, e.g. by the Hauptamt Volksdeutsche Mittelstelle. However, by 1939 more than half of Polish Germans lived outside of the formerly German territories of Poland due to improving economic opportunities.