Former eastern territories of Germany

Map of Poland under Duke Mieszko I, whose conversion to Christianity and recognition by the papacy, marks the beginning of Polish statehood, 966 AD

As various Germanic tribes settled in the region of central Europe, to the east several different West Slavic tribes inhabited most of the area of present-day Poland from the 6th century. Duke Mieszko I of the Polans, from his stronghold in the Gniezno area, united various neighboring tribes in the second half of the 10th century, forming the first Polish state and becoming the first historically recorded Piast duke. His realm bordered German state, and control over the borderlands would shift back and forth between the two polities over the centuries to come.

Mieszko's son and successor, Duke Bolesław I Chrobry, upon the 1018 Peace of Bautzen expanded the southern part of the realm, but lost control over the lands of Western Pomerania on the Baltic coast. After pagan revolts and a Bohemian invasion in the 1030s, Duke Casimir I the Restorer (reigned 1040-1058) again united most of the former Piast realm, including Silesia and Lubusz Land on both sides of the middle Oder River, but without Western Pomerania, which became part of the Polish state again under Bolesław III Wrymouth from 1116 until 1121, when the noble House of Griffins established the Duchy of Pomerania. On Bolesław's death in 1138, Poland for almost 200 years was subjected to fragmentation, being ruled by Bolesław's sons and by their successors, who were often in conflict with each other. Władysław I the Elbow-high, crowned king of Poland in 1320, achieved partial reunification, although the Silesian and Masovian duchies remained independent Piast holdings.

Phases of German Ostsiedlung, 8th to 14th century adapted from Walter Kuhn

In the course of the 12th to 14th centuries, Germanic, Dutch and Flemish settlers moved into East Central and Eastern Europe in a migration process known as the Ostsiedlung. In Pomerania, Brandenburg, Prussia and Silesia, the former West Slav (Polabian Slavs and Poles) or Balt population became minorities in the course of the following centuries, although substantial numbers of the original inhabitants remained in areas such as Upper Silesia. In Greater Poland and in Eastern Pomerania (Pomerelia), German settlers formed a minority. Some of the territories (such as Pomerelia and Masovia) reunited with Poland during the 15th and 16th centuries. Others became more firmly incorporated into German polities.

In 1815, the Congress of Vienna established The German Confederation (German: Deutscher Bund) as an association of 39 German-speaking states in Central Europe. This established the boundaries of Germany for much of the 19th century; as including Pomerania, East Brandenburg and Silesia, but excluding German-speaking lands in the eastern portion of the Kingdom of Prussia (East Prussia, West Prussia and Posen), as well as the German cantons of Switzerland, and the French region of Alsace.

Location of the annexed part (orange) of the Province of Pomerania and of the other formerly German territories (green)

The Pomeranian parts of the former eastern territories of Germany had been under Polish rule several times from the late 10th century on, when Mieszko I acquired at least significant parts of them. Mieszko's son Bolesław I established a bishopric in the Kołobrzeg area in 1000–1005/07, before the area was lost by Poland again to pagan Slavic tribes. Despite further attempts by Polish dukes to again control the Pomeranian tribes, this was only partly achieved by Bolesław III in several campaigns lasting from 1116 to 1121. Successful Christian missions ensued in 1124 and 1128; however, by the time of Bolesław's death in 1138, most of West Pomerania (the Griffin-ruled areas) was no longer controlled by Poland. The easternmost part of later Western/Farther Pomerania[Note 1] in the 13th century was part of Gdańsk Pomerania and was re-integrated with Poland, and later on, in the 14th and 15th centuries formed a duchy, whose rulers were vassals of the Jagiellonian-ruled Kingdom of Poland, before it was integrated with Western/Farther Pomerania. Over the following centuries the area was largely Germanized, although a small Slavic or Polish minority remained. The Duchy of Pomerania under the native Griffin dynasty existed for over 500 years, before it was partitioned between Sweden and Brandenburg-Prussia in the 17th century. The Swedish-controlled areas fell to the Kingdom of Prussia in the 18th and 19th century.

At the turn of the 20th century there lived only about 14,200 persons of Polish mother-tongue in the Province of Pomerania (in the east of Farther Pomerania in the vicinity of the border with West Prussia), and 300 persons using the Kashubian language (at the Leba Lake and the Garde Lake), the total population of the province consisting of almost 1.7 million inhabitants.

Ducal Prussia (to 1525 Monastic state of the Teutonic Knights) as a feudal fief of the Crown of the Polish Kingdom 1466-1657

Location of the former Free City of Danzig (orange) and of the other Recovered Territories (green)

The region of Pomerelia/Gdańsk Pomerania at the eastern end of Pomerania, including Gdańsk (Danzig), was part of Poland since its first ruler Mieszko I. As a result of the fragmentation of Poland, it was ruled in the 12th and 13th centuries by the Samborides, who were (at least initially) more closely tied to the Kingdom of Poland than were the Griffins. After the Treaty of Kępno in 1282, and the death of the last Samboride in 1294, the region was ruled by kings of Poland for a short period, although also claimed by Brandenburg. After the Teutonic takeover in 1308 the region was annexed to the monastic state of the Teutonic Knights. In the Second Peace of Thorn (1466) most of the region became part of Royal Prussia within the Kingdom of Poland, as it remained until being annexed by the Kingdom of Prussia in the partitions of 1772 and 1793. A small area in the west of Pomerelia, the Lauenburg and Bütow Land (the region of Lębork and Bytów) was granted to the rulers of Pomerania as a Polish fief, before being reintegrated with Poland in 1637, and later on, again transformed into a Polish fief, which it remained until the First Partition of Poland. The Prussian province of West Prussia was formed from Royal Prussia in 1773.

Location of East Brandenburg (orange) and of the other formerly German territories (green)

Lubusz Land during the Piast period (marked in yellow).

The medieval Lubusz Land on both sides of the Oder River up to the Spree in the west, including Lubusz (Lebus) itself, also formed part of Mieszko's realm. Poland lost Lubusz when the Silesian duke Bolesław II Rogatka sold it to the Ascanian margraves of Brandenburg in 1249. Brandenburg also acquired the castellany of Santok from Duke Przemysł I of Greater Poland and made it the nucleus of their Neumark ("New March") region. The Bishopric of Lebus remained a suffragan of the Archdiocese of Gniezno until 1424, when it passed under the jurisdiction of the Archbishopric of Magdeburg. The Lubusz Land was part of the Lands of the Bohemian (Czech) Crown from 1373 to 1415.

Location of Posen-West Prussia (orange) and of the other former eastern territories of Germany (green)

A portion of the former eastern territory east of the Lubusz Land had previously formed the western parts of the Polish provinces of Pomerelia and Greater Poland (Polonia Maior), being lost to Prussia in the First Partition (the Pomerelian parts) and the Second Partition (the remainder). During Napoleonic times the Greater Poland territories formed part of the Duchy of Warsaw, but after the Congress of Vienna Prussia reclaimed them as part of the Grand Duchy of Posen (Poznań), later Province of Posen.

Location of Silesia (orange) in the former eastern territories of Germany (green)

Silesia formed part of Poland since Mieszko I of Poland and Piast dukes continued to rule Silesia following the 12th-century fragmentation of Poland. In the 14th century, by the Treaty of Trentschin King Casimir III the Great gave up all Polish claims to Silesia and ceded the Duchies of Silesia to the Kingdom of Bohemia, an Electorate of the Holy Roman Empire. It was briefly under Hungarian rule in the 15th century. Under the Bohemian crown, most of the region continued to be ruled by branches of the Piast dynasty known as the Silesian Piasts. Silesia passed to the Habsburg Monarchy of Austria in 1526. Frederick the Great conquered Silesia in 1742 and the Habsburg Monarchy ceded most of the region to the Kingdom of Prussia in the Treaties of Breslau and Berlin.

The first German colonists arrived in the late 12th century, and large-scale German settlement started in the early 13th century during the reign of Henry I[16] (Duke of Silesia from 1201 to 1238 and of all-Poland from 1232 to 1238). After the era of German colonisation, the Polish language still predominated in Upper Silesia and in parts of Lower and Middle Silesia north of the Oder river. Here the Germans who arrived during the Middle Ages became mostly Polonized; Germans dominated in large cities and Poles mostly in rural areas. The Polish-speaking parts of Lower and Middle Silesia, commonly described until the end of the 19th century as the Polish side, were mostly Germanized in the 18th and 19th centuries, except for some areas along the northeastern frontier.[17][18]

History of Brandenburg and Prussia
Northern March 965–983		Old Prussians pre-13th century
Lutician federation 983 – 12th century
Margraviate of Brandenburg 1157–1618 (1806) (HRE) (Bohemia 1373–1415)		Teutonic Order 1224–1525 (Polish fief 1466–1525)
		Duchy of Prussia 1525–1618 (1701) (Polish fief 1525–1657)		Royal (Polish) Prussia (Poland) 1454/1466 – 1772
Brandenburg-Prussia 1618–1701
Kingdom in Prussia 1701–1772
Kingdom of Prussia 1772–1918
Free State of Prussia (Germany) 1918–1947			Klaipėda Region (Lithuania) 1920–1939 / 1945–present	Recovered Territories (Poland) 1918/1945–present
Brandenburg (Germany) 1947–1952 / 1990–present		Kaliningrad Oblast (Russia) 1945–present

Location of southern East Prussia (orange) and of the other former eastern territories of Germany (green)

The northern territories of Warmia and Masuria form the areas of the former eastern territories of Germany that had been Polish fiefs. Originally inhabited by pagan Old Prussians, these regions became were conquered and incorporated into the state of the Teutonic Knights in the 13th and 14th centuries. By the Second Peace of Thorn (1466), Warmia was awarded to the Polish Crown as part of Royal Prussia, though with considerable autonomy, while Masuria became part of a Polish fief, first as part of the Teutonic state, and from 1525 as part of the secular Ducal Prussia. Prussia took direct control of the region in the First Partition of Poland (1772) and in 1773 included the area in the newly formed province of East Prussia.

German atlas from 1880 showing the spread of languages.

Partitions of Poland in 1772, 1793 and 1795 – Russian Partition (red), Austrian Partition (green), and Prussian Partition (blue)

Growth of Brandenburg-Prussia (1600–1795).

At the time of the foundation of the German Empire in 1871, the Kingdom of Prussia was the largest and dominant part of the empire. Prussian territory east of the Oder–Neisse line included West Prussia and Posen (taken by Prussia in the first two Partitions of Poland in the 18th century), also Silesia, East Brandenburg, and Pomerania. Later, these territories would come to be called in Germany "Ostgebiete des deutschen Reiches" (Eastern territories of the German Empire). After 1871, the boundaries of 'Germany' came to be understood as having been extended to include the whole of Prussian territory.

German territorial losses after the Treaty of Versailles

The Treaty of Versailles of 1919 that ended World War I restored the independence of Poland, known as the Second Polish Republic, and Germany was compelled to cede territories to it, most of which were taken by Prussia in the three Partitions of Poland, and had been part of the Kingdom of Prussia and later the German Empire for over 100 years. The territories ceded to Poland in 1919 were those with an apparent Polish majority, such as the Province of Posen, the east-southern part of Upper Silesia and the so-called Polish Corridor.

Those parts of the former Province of Posen and of West Prussia that were not restored as part of the Second Polish Republic were administered as Grenzmark Posen-Westpreußen (the German Province of Posen–West Prussia) until 1939.

In October 1938 Hlučín Area (Hlučínsko in Czech, Hultschiner Ländchen in German) of Moravian-Silesian Region which had been ceded to Czechoslovakia under the Treaty of Versailles was annexed by the Third Reich as a part of areas lost by Czechoslovakia in accordance with the Munich agreement. However, as distinct from other lost Czechoslovakian domains, it was not attached to Sudetengau (administrative region covering Sudetenland) but to Prussia (Upper Silesia).

By late 1938, Lithuania had lost control over the situation in the Memel Territory. In the early hours of 23 March 1939, after a political ultimatum caused a Lithuanian delegation to travel to Berlin, the Lithuanian Minister of Foreign Affairs Juozas Urbšys and his German counterpart Joachim von Ribbentrop signed the Treaty of the Cession of the Memel Territory to Germany in exchange for a Lithuanian Free Zone in the port of Memel, using the facilities erected in previous years.

In the interwar period the German administration, both Weimar and Nazi, conducted a massive campaign of renaming of thousands of placenames, to remove traces of Polish, Lithuanian and Old Prussian origin.

Map of Reichsgaue in 1941

Between the two world wars, many in Germany claimed that the territory ceded to Poland in 1919–1922 should be returned to Germany. This claim was one of the justifications for the German invasion of Poland in 1939, heralding the start of the Second World War. The Third Reich annexed the former German lands, comprising the "Polish Corridor", West Prussia, the Province of Posen, and parts of eastern Upper Silesia. The council of the Free City of Danzig voted to become a part of Germany again, although Poles and Jews were deprived of their voting rights and all non-Nazi political parties were banned. In addition to taking territories lost in 1919, Germany also took additional land that had never been German.

Two decrees by Adolf Hitler (October 8 and October 12, 1939) divided the annexed areas of Poland into administrative units:

• Reichsgau Wartheland (initially Reichsgau Posen), which included the entire Poznań Voivodeship, most of the Łódź Voivodeship, five counties of the Pomeranian Voivodeship, and one county of the Warszawa Voivodeship;
• Reichsgau Danzig-West Prussia (initially Reichsgau West Prussia), which consisted of the remaining area of the Pomeranian Voivodeship and the Free City of Danzig;
• Ciechanów District (Regierungsbezirk Zichenau), consisting of the five northern counties of Warszawa Voivodeship (Płock, Płońsk, Sierpc, Ciechanów, and Mława), which became a part of East Prussia;
• Katowice District (Regierungsbezirk Kattowitz), or East Upper Silesia (Ost-Oberschlesien), which included Sosnowiec, Będzin, Chrzanów, and Zawiercie Counties, and parts of Olkusz and Żywiec Counties.

These territories had an area of 94,000 km² and a population of 10,000,000 people. Throughout the war, the annexed Polish territories were subject to German colonization. Because of the lack of settlers from Germany itself, the colonists were primarily ethnic Germans relocated from other parts of Eastern Europe. These ethnic Germans were then resettled in homes from which the Poles had been expelled.

The remainder of Polish territory was annexed by the Soviet Union (see Molotov–Ribbentrop Pact) or made into the German-controlled General Government occupation zone.

After the German attack on the Soviet Union in June 1941, the district of Białystok, which included the Białystok, Bielsk Podlaski, Grajewo, Łomża, Sokółka, Volkovysk, and Grodno Counties, was "attached to" (not incorporated into) East Prussia, whilst Eastern Galicia (District of Galicia), which included the cities of Lwów, Stanislawów and Tarnopol, was made part of the General Government.

The final decision to move Poland's boundary westward was made by the United States, the United Kingdom and the Soviet Union at the Yalta Conference in February 1945, shortly before the end of the war. The precise location of the border was left open; the western Allies also accepted in general the principle of the Oder River as the future western border of Poland and of population transfer as the way to prevent future border disputes. The open question was whether the border should follow the Eastern or Lusatian Neisse rivers, and whether Stettin, the traditional seaport of Berlin, should remain German or be included in Poland.

Originally, Germany was to retain Stettin while the Poles were to annex East Prussia with Königsberg.[31] Eventually, however, Stalin decided that he wanted Königsberg as a year-round warm water port for the Soviet Navy and argued that the Poles should receive Stettin instead. The wartime Polish government in exile had little to say in these decisions.[31]

At the Yalta Conference, it was agreed to split Germany into four occupation zones after the war, with a quadripartite occupation of Berlin as well, prior to unification of Germany. The status of Poland was discussed, but was complicated by the fact that Poland was at this time under the control of the Red Army. It was agreed to reorganize the Provisionary Polish Government that had been set up by the Red Army through the inclusion of other groups such as the Polish Provisional Government of National Unity and to have democratic elections. This effectively excluded the Polish government-in-exile that had evacuated in 1939. It was agreed that the Polish eastern border would follow the Curzon Line, and Poland would receive substantial territorial compensation in the west from Germany, although the exact border was to be determined at a later time. A "Committee on Dismemberment of Germany" was to be set up. The purpose was to decide whether Germany was to be divided into six nations, and if so, what borders and inter-relationships the new German states were to have.

Occupied Germany in 1947. Territories east of the Oder-Neisse line were annexed by Poland and the Soviet Union under the terms of the Potsdam Agreement.

Germany subsequently lost territories east of the Oder–Neisse Line at the end of the War in 1945, when international recognition of its right to jurisdiction over any of these territories was conditionally withdrawn. The "condition" mentioned was the Final German Peace Treaty, which was to set the actual border line, which might or might not deviate from the rivers Oder and Neisse. At Potsdam, the assumption by many was that a Final German Peace Treaty was imminent, but this turned out to be incorrect.

After World War II, as agreed at the Potsdam Conference (which was held from 17 July until 2 August 1945), all of the areas east of the Oder–Neisse line, whether recognised by the international community as part of Germany until 1939 or occupied by Germany during World War II, were placed under the jurisdiction of other countries.The relevant paragraphs in the Potsdam Agreement are:[32][33][34]

V. City of Koenigsberg and the adjacent area.

The Conference examined a proposal by the Soviet Government to the effect that pending the final determination of territorial questions at the peace settlement, the section of the western frontier of the Union of Soviet Socialist Republics which is adjacent to the Baltic Sea should pass from a point on the eastern shore of the Bay of Danzig to the east, north of Braunsberg-Goldap, to the meeting point of the frontiers of Lithuania, the Polish Republic and East Prussia.

The Conference has agreed in principle to the proposal of the Soviet Government concerning the (ultimate)[35] transfer to the Soviet Union of the City of Koenigsberg and the area adjacent to it as described above subject to expert examination of the actual frontier.

The President of the United States and the British Prime Minister have declared that they will support the proposal of the Conference at the forthcoming peace settlement.

VIII. Poland.

...

The British and United States Governments have taken measures to protect the interest of the Polish Provisional Government of National Unity as the recognized government of the Polish State in the property belonging to the Polish State located in their territories and under their control, whatever the form of this property may be.

...

In conformity with the agreement on Poland reached at the Crimea Conference the three Heads of Government have sought the opinion of the Polish Provisional Government of National Unity in regard to the accession of territory in the north and west which Poland should receive. The President of the National Council of Poland and members of the Polish Provisional Government of National Unity have been received at the Conference and have fully presented their views. The three Heads of Government reaffirm their opinion that the final delimitation of the western frontier of Poland should await the peace settlement.

The three Heads of Government agree that, pending the final determination of Poland's western frontier, the former German territories east of a line running from the Baltic Sea immediately west of Swinamunde, and thence along the Oder River to the confluence of the western Neisse River and along the Western Neisse to the Czechoslovak frontier, including that portion of East Prussia not placed under the administration of the Union of Soviet Socialist Republics in accordance with the understanding reached at this conference and including the area of the former free city of Danzig, shall be under the administration of the Polish State and for such purposes should not be considered as part of the Soviet zone of occupation in Germany. (Emphasis added)

The Allies also agreed that:

XII. Orderly transfer of German populations. The Three Governments [of the Soviet Union, the United States and Great Britain], having considered the question in all its aspects, recognize that the transfer to Germany of German populations, or elements thereof, remaining in Poland, Czechoslovakia and Hungary, will have to be undertaken. They agree that any transfers that take place should be effected in an orderly and humane manner.

because in the words of Winston Churchill

Expulsion is the method which, in so far as we have been able to see, will be the most satisfactory and lasting. There will be no mixture of populations to cause endless trouble. A clean sweep will be made.[36]

The problem with the status of these territories was that the Potsdam Agreement was not a legally binding treaty, but a memorandum between the USSR, the US and the UK (to which the French were not party). It regulated the issue of the eastern German border, which was confirmed as being along the Oder–Neisse line, but the final article of the memorandum said that the final decisions concerning Germany, and hence the detailed alignment of Germany's eastern boundaries, would be subject to a separate peace treaty; at which the three Allied signatories committed themselves to respect the terms of the Potsdam memorandum. Hence, so long as these Allied Powers remained committed to the Potsdam protocols, without German agreement to an Oder–Neisse line boundary there could be no Peace Treaty and no German Reunification. This treaty was signed in 1990 as the Treaty on the Final Settlement with Respect to Germany.[37][38]

With the rapid advance of the Red Army in the winter of 1944–1945, German authorities desperately evacuated many Germans westwards. The majority of the remaining German-speaking population in the territory of former Czechoslovakia and east of the Oder–Neisse line (roughly 10 million in the ostgebiete alone), that had not already been evacuated, was expelled by the new Czech and Polish administrations. Although in the post-war period earlier German sources often cited the number of evacuated and expelled Germans at 16 million and the death toll at between 1.7[39] and 2.5 million,[40] today, the numbers are considered by some historians to be exaggerated and the death toll more likely in a range between 400,000 and 600,000.[41] Some present-day estimates place the numbers of German refugees at 14 million of which about half a million died during the evacuations and expulsions.[41][42]

At the same time, Poles from central Poland, expelled Poles from former eastern Poland, Polish returnees from internment and forced labour, Ukrainians forcibly resettled in Operation Vistula, and Jewish Holocaust survivors were settled in German territories gained by Poland, whereas the north of former East Prussia (Kaliningrad Oblast gained by the USSR) was turned into a military zone and subsequently settled with Russians.

During the Polish post-war census of December 1950, data about the pre-war places of residence of the inhabitants as of August 1939 was collected. In case of children born between September 1939 and December 1950, their place of residence was reported based on the pre-war places of residence of their mothers. Thanks to this data it is possible to reconstruct the pre-war geographical origin of the post-war population in the Recovered Territories of Poland . Many areas located near the pre-war German border were resettled by people from neighbouring borderland areas of pre-war Poland. For example, Kashubians from pre-war Polish Corridor settled in nearby areas of German Pomerania adjacent to Polish Pomerania. People from Poznań region of pre-war Poland settled in East Brandenburg. People from East Upper Silesia moved into the rest of Silesia. And people from Masovia and from Sudovia moved into adjacent Masuria. Poles expelled from former Polish territories in the east (today mainly parts of Ukraine, Belarus and Lithuania) settled in large numbers everywhere in the Recovered Territories (but many of them also settled in central Poland).

In the 1970s, West Germany adopted Ostpolitik in foreign relations, which strove to normalise relations with its neighbours by recognising the realities of the European order of the time,[44] and abandoning elements of the Hallstein Doctrine. West Germany also abandoned for the time being its claims with respect to German self-determination and reunification, recognising the existence of the German Democratic Republic (GDR); and the validity of the Oder–Neisse line in international law."[44] As part of this new approach, West Germany concluded friendship treaties with the Soviet Union (Treaty of Moscow (1970)), Poland (Treaty of Warsaw (1970)), East Germany (Basic Treaty (1972)) and Czechoslovakia (Treaty of Prague (1973)); and participated in the Helsinki Final Act (1975). Nevertheless, West Germany continued its long term objective of achieving a reunification of East Germany, West Germany and Berlin; and maintained that its formal recognition of the post-war boundaries of Germany would need to be confirmed by a united Germany in the context of a Final Settlement of the Second World War. Some West German commentators continued to maintain that neither the Treaty of Zgorzelec nor the Treaty of Warsaw should be considered as binding on a future united Germany; albeit that these reservations were intended for domestic political consumption, and the arguments advanced in support of them had no substance in international law.