Former eastern territories of Germany

The former eastern territories of Germany (German: Ehemalige deutsche Ostgebiete) refer in present-day Germany to those territories east of the current eastern border of Germany, i.e., the Oder–Neisse line, which historically had been considered German and which were annexed by Poland and the Soviet Union after World War II in Europe. In most of these territories, Germans used to be the dominant or sole ethnicity.^[1] In contrast to the lands awarded to the restored Polish state by the Treaty of Versailles after World War I, the German territories lost with the Potsdam Agreement after World War II in Europe on 2 August 1945 were either almost exclusively inhabited by Germans before 1945 (the bulk of East Prussia, Lower Silesia, Farther Pomerania, and parts of Western Pomerania, Lusatia, and Neumark), mixed German-Polish with a German majority (the Posen-West Prussia Border March, Lauenburg and Bütow Land, the southern and western rim of East Prussia, Ermland, Western Upper Silesia, and the part of Lower Silesia east of the Oder), or mixed German-Czech with a German majority (Glatz). Virtually the entire German population of the territories that did not flee voluntarily in the face of the Red Army advance of 1945, was violently expelled to Germany, with their possessions being seized and looted.

The ceding of the east German lands to Poland was done in large part to compensate Poland for losing the Kresy lands east of the Curzon line to the Soviet Union; this territory had large populations of Ukrainians and Belarusians, the ethnic groups of two of the western republics of the Soviet Union. The territories acquired by Poland after World War II are known there as the Recovered Territories.^[2] The territories Poland annexed had been ruled as part of Poland by the Piast dynasty in the High Middle Ages, with the exception of southern East Prussia, which originally was inhabited by Old Prussians and came under Polish suzerainty in the Late Middle Ages. The northern part of East Prussia was annexed by the Russian Soviet Federative Socialist Republic as the Kaliningrad Oblast, now forming a Russian exclave.

The post-war border between Germany and Poland along the Oder–Neisse line was defined in August 1945 by the Potsdam Agreement of the leaders of the three main Allies of World War II, the Soviet Union, the United Kingdom, and the United States; and was formally recognized by East Germany in 1950, by the Treaty of Zgorzelec, under pressure from Stalin. In 1952, recognition of the Oder–Neisse line as a permanent boundary was one of Stalin's conditions for the Soviet Union to agree to a reunification of Germany (see Stalin Note). The offer was rejected by Konrad Adenauer, Chancellor of West Germany. The then official West German government position on the status of the former territories of Germany east of the Oder and Neisse rivers was that the areas were "temporarily under Polish [or Soviet] administration", because the border regulation at the Potsdam Conference had been taken as preliminary provisions to be revisited at a final peace conference which, due to the Cold War, had been indefinitely postponed;^[3] however, West Germany in 1972 recognised the Oder–Neisse line as the western boundary of Poland when the 1970 Treaty of Warsaw between West Germany and Poland took effect; and in 1973, the Federal Constitutional Court acknowledged the capability of East Germany to negotiate the Treaty of Zgorzelec as an international agreement binding as a legal definition of its boundaries. In signing the Helsinki Final Act in 1975, both West Germany and East Germany recognised the existing boundaries of post-war Europe, including the Oder–Neisse line, as valid in international law.

In 1990, as part of the reunification of Germany, both German countries accepted clauses in the peace treaty with the four countries representing the Allies (Treaty on the Final Settlement With Respect to Germany) to replace the Potsdam Agreement, whereby Germany renounced all claims to territory outside East and West Germany.^[4] As the result of this treaty, Germany's recognition of the Oder–Neisse line as the border was formalised by the re-united Germany in the German–Polish Border Treaty on 14 November 1990 and by the repeal of Article 23 of the Basic Law for the Federal Republic of Germany under which German states outside the Federal Republic could formerly have declared their accession. Germany went from a territory of 468,787 km^2[5] before the 1938 annexation of Austria to 357,022 km^2[6] after the 1990 reunification of Germany, a loss of 24%.^[7] Despite its acquisition of the formerly German territory, the war also saw Poland's territory reduced by about 20% overall because of its losses in the east to the Soviets.