Territories Of Poland Annexed By The Soviet Union
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Seventeen days after the German
invasion of Poland The invasion of Poland, also known as the September Campaign, Polish Campaign, and Polish Defensive War of 1939 (1 September – 6 October 1939), was a joint attack on the Second Polish Republic, Republic of Poland by Nazi Germany, the Slovak R ...
in 1939, which marked the beginning of the
Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
, the
Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
entered the eastern regions of
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...
(known as the ) and annexed territories totalling with a population of 13,299,000. Inhabitants besides ethnic
Poles Pole or poles may refer to: People *Poles (people), another term for Polish people, from the country of Poland * Pole (surname), including a list of people with the name * Pole (musician) (Stefan Betke, born 1967), German electronic music artist ...
included Belarusian and Ukrainian major population groups, and also
Czechs The Czechs (, ; singular Czech, masculine: ''Čech'' , singular feminine: ''Češka'' ), or the Czech people (), are a West Slavs, West Slavic ethnic group and a nation native to the Czech Republic in Central Europe, who share a common Bohemia ...
,
Lithuanians Lithuanians () are a Balts, Baltic ethnic group. They are native to Lithuania, where they number around 2,378,118 people. Another two million make up the Lithuanian diaspora, largely found in countries such as the Lithuanian Americans, United Sta ...
,
Jews Jews (, , ), or the Jewish people, are an ethnoreligious group and nation, originating from the Israelites of History of ancient Israel and Judah, ancient Israel and Judah. They also traditionally adhere to Judaism. Jewish ethnicity, rel ...
, and other minority groups. These annexed territories were subsequently incorporated into the Lithuanian, Byelorussian, and Ukrainian Soviet Socialist Republics and remained within the Soviet Union in 1945 as a consequence of European-wide territorial rearrangements configured during the
Tehran Conference The Tehran Conference (codenamed Eureka) was a strategy meeting of the Allies of World War II, held between Joseph Stalin, Franklin D. Roosevelt, and Winston Churchill from 28 November to 1 December 1943. It was the first of the Allied World Wa ...
of 1943 (see Western Betrayal). Poland was compensated for this territorial loss with the pre-War German eastern territories, at the expense of losing its eastern regions. The
Polish People's Republic The Polish People's Republic (1952–1989), formerly the Republic of Poland (1947–1952), and also often simply known as Poland, was a country in Central Europe that existed as the predecessor of the modern-day democratic Republic of Poland. ...
regime described the territories as the " Recovered Territories". The number of Poles in the Kresy in the year 1939 was around 5.274 million, but after
ethnic cleansing Ethnic cleansing is the systematic forced removal of ethnic, racial, or religious groups from a given area, with the intent of making the society ethnically homogeneous. Along with direct removal such as deportation or population transfer, it ...
in 1939-1945 by Nazi Germany, the Soviet Union and Ukrainian nationalist forces, Kresy consisted of approximately 1.8 million inhabitants. The post-World War II territory of Poland was slightly smaller than the pre-1939 land areas, shrinking by some (roughly equalling that of the territories of
Belgium Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. Situated in a coastal lowland region known as the Low Countries, it is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeas ...
and the
Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...
combined).


Molotov–Ribbentrop Pact

Early in the morning of August 24, 1939, the Soviet Union and
Nazi Germany Nazi Germany, officially known as the German Reich and later the Greater German Reich, was the German Reich, German state between 1933 and 1945, when Adolf Hitler and the Nazi Party controlled the country, transforming it into a Totalit ...
signed a 10-year non-aggression pact, called the
Molotov–Ribbentrop pact The Molotov–Ribbentrop Pact, officially the Treaty of Non-Aggression between Germany and the Union of Soviet Socialist Republics, and also known as the Hitler–Stalin Pact and the Nazi–Soviet Pact, was a non-aggression pact between Nazi Ge ...
. Most notably, the pact contained a secret protocol, revealed only after Germany's defeat in 1945, according to which the states of Northern and
Eastern Europe Eastern Europe is a subregion of the Europe, European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural and socio-economic connotations. Its eastern boundary is marked by the Ural Mountain ...
were divided into German and Soviet "
spheres of influence In the field of international relations, a sphere of influence (SOI) is a spatial region or concept division over which a state or organization has a level of cultural, economic, military, or political exclusivity. While there may be a formal a ...
".''Text of the Nazi-Soviet Non-Aggression Pact''
executed August 23, 1939
In the North,
Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...
,
Estonia Estonia, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Ru ...
and
Latvia Latvia, officially the Republic of Latvia, is a country in the Baltic region of Northern Europe. It is one of the three Baltic states, along with Estonia to the north and Lithuania to the south. It borders Russia to the east and Belarus to t ...
were assigned to the Soviet sphere. Poland was to be partitioned in the event of its "political rearrangement"—the areas east of the Narev,
Vistula The Vistula (; ) is the longest river in Poland and the ninth-longest in Europe, at in length. Its drainage basin, extending into three other countries apart from Poland, covers , of which is in Poland. The Vistula rises at Barania Góra i ...
and San Rivers going to the Soviet Union while Germany would occupy the west. Initially annexed by Poland in a series of wars between 1918 and 1921 (primarily the Polish-Soviet War), these territories had mixed urban national populations with
Poles Pole or poles may refer to: People *Poles (people), another term for Polish people, from the country of Poland * Pole (surname), including a list of people with the name * Pole (musician) (Stefan Betke, born 1967), German electronic music artist ...
and
Ukrainians Ukrainians (, ) are an East Slavs, East Slavic ethnic group native to Ukraine. Their native tongue is Ukrainian language, Ukrainian, and the majority adhere to Eastern Orthodox Church, Eastern Orthodoxy, forming the List of contemporary eth ...
being the most numerous ethnic groups, with significant minorities of
Belarusians Belarusians ( ) are an East Slavs, East Slavic ethnic group native to Belarus. They natively speak Belarusian language, Belarusian, an East Slavic language. More than 9 million people proclaim Belarusian ethnicity worldwide. Nearly 7.99&n ...
and
Jews Jews (, , ), or the Jewish people, are an ethnoreligious group and nation, originating from the Israelites of History of ancient Israel and Judah, ancient Israel and Judah. They also traditionally adhere to Judaism. Jewish ethnicity, rel ...
. Also in: ''Wrocławskie Studia Wschodnie'', Wrocław, 1997. Much of this rural territory had its own significant local non-Polish majority (Ukrainians in the south and Belarusians in the north). Jan Tomasz Gross, ''Revolution from Abroad'', pp. 4, 5, Princeton, 2005,
Google books link)
/ref>
Lithuania Lithuania, officially the Republic of Lithuania, is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea, bordered by Latvia to the north, Belarus to the east and south, P ...
, adjacent to
East Prussia East Prussia was a Provinces of Prussia, province of the Kingdom of Prussia from 1772 to 1829 and again from 1878 (with the Kingdom itself being part of the German Empire from 1871); following World War I it formed part of the Weimar Republic's ...
, would be in the German sphere of influence, although a second secret protocol agreed in September 1939 assigned the majority of Lithuania to the USSR.Christie, Kenneth, ''Historical Injustice and Democratic Transition in Eastern Asia and Northern Europe: Ghosts at the Table of Democracy'', RoutledgeCurzon, 2002, According to the secret protocol, Lithuania would retrieve its historical capital
Vilnius Vilnius ( , ) is the capital of and List of cities in Lithuania#Cities, largest city in Lithuania and the List of cities in the Baltic states by population, most-populous city in the Baltic states. The city's estimated January 2025 population w ...
, subjugated during the inter-war period by
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...
.


Soviet annexation of eastern Poland, 1939–1941

The Polish–Soviet border, as of 1939, had been determined in 1921 at the Treaty of Riga peace talks, which followed the
Polish–Soviet War The Polish–Soviet War (14 February 1919 – 18 March 1921) was fought primarily between the Second Polish Republic and the Russian Soviet Federative Socialist Republic, following World War I and the Russian Revolution. After the collapse ...
. Under the terms of the Molotov–Ribbentrop Pact, two weeks after the German invasion of western Poland, the Soviet Union invaded the portions of eastern Poland assigned to it by the Pact, followed by co-ordination with German forces in Poland. See map. During the Interbellum period, the
Second Polish Republic The Second Polish Republic, at the time officially known as the Republic of Poland, was a country in Central and Eastern Europe that existed between 7 October 1918 and 6 October 1939. The state was established in the final stage of World War I ...
had carried out an oppressive programme of
Polonization Polonization or Polonisation ()In Polish historiography, particularly pre-WWII (e.g., L. Wasilewski. As noted in Смалянчук А. Ф. (Smalyanchuk 2001) Паміж краёвасцю і нацыянальнай ідэяй. Польскі ...
against its Ukrainian, Belarusian, and Jewish minorities. In a programme referred to as the
Pacification of Ukrainians in Eastern Galicia The Pacification of Ukrainians in Eastern Galicia was a punitive action against the Ukrainians in Galicia, carried out by police and military of the Second Polish Republic from September until November 1930 in reaction to a wave of sabotage and ...
, the buildings, belongings, and property of Ukrainians were destroyed and their inhabitants were often beaten and arrested. According to Ukrainian-Canadian historian, Orest Subtelny, these events constituted "collective punishment" meted out on thousands of "mostly innocent peasants" and resulted in the exacerbation of animosity between the Polish state and the Ukrainian minority. Similar oppressive actions were also carried out against the Belarusian population of Poland. The Soviet Union cited a "need to protect" the Ukrainian and Belarusian majority populations in these regions as a reason justifying the Soviet invasion of Eastern Poland (including Western Ukraine and Belarus), carried out in the wake of Poland's dismemberment under the Nazi invasion with Warsaw being besieged and with Poland's government being in the process of evacuation.''Telegram of the German Ambassador in the Soviet Union, (Schulenburg) to the German Foreign Office Moscow,'' Moscow, September 16 : ''...the Soviet Union had thus far not concerned itself about the plight of its minorities in Poland and had to justify abroad, in some way or other, its present intervention. Consequently, many
Ukrainians Ukrainians (, ) are an East Slavs, East Slavic ethnic group native to Ukraine. Their native tongue is Ukrainian language, Ukrainian, and the majority adhere to Eastern Orthodox Church, Eastern Orthodoxy, forming the List of contemporary eth ...
,
Belarus Belarus, officially the Republic of Belarus, is a landlocked country in Eastern Europe. It is bordered by Russia to the east and northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Belarus spans an a ...
ians and
Jew Jews (, , ), or the Jewish people, are an ethnoreligious group and nation, originating from the Israelites of ancient Israel and Judah. They also traditionally adhere to Judaism. Jewish ethnicity, religion, and community are highly inte ...
s welcomed the Soviet troops into the occupied territories. The total area, including the area given to Lithuania, was , with a population of 13.299 million, of which 5.274 million were ethnic Poles and 1.109 million were Jews. An additional 138,000 ethnic Poles and 198,000 Jews fled the German occupied zone and became refugees in the Soviet occupied region.Poland's Holocaust, Tadeusz Piotrowski, 1998 p. 14 The borders were finalized in the September 28 German–Soviet Frontier Treaty, most of whose contents were kept secret. Soviet authorities immediately started a campaign of sovietization. Passportization and residence registration of the population in the newly acquired territories began. Inhabitants of
Kresy Eastern Borderlands (), often simply Borderlands (, ) was a historical region of the eastern part of the Second Polish Republic. The term was coined during the interwar period (1918–1939). Largely agricultural and extensively multi-ethnic with ...
, on whom Soviet citizenship was imposed in November 1939, had to return documents issued by "former Poland" and obtain new citizenship of the USSR. The
NKVD The People's Commissariat for Internal Affairs (, ), abbreviated as NKVD (; ), was the interior ministry and secret police of the Soviet Union from 1934 to 1946. The agency was formed to succeed the Joint State Political Directorate (OGPU) se ...
used the passportization system to carefully select people still living in Western Belarus and Western Ukraine. Those who did not receive the citizenship or refused to accept it (claiming that they were Polish citizens or not agreeing to enter Ukrainian or Belarusian nationality) were arrested or deported. In March 1940, the authorities also decided about the fate of refugees from western Poland, who from September 1939 were in Kresy. Deportation of this group of about 75–80 thousand people, consisting mainly of Jews (about 84%), finally began on June 29, 1940, and lasted for nearly a month. The Soviets organized staged elections, the result of which was to become a legitimization of Soviet annexation of eastern Poland.
/ref> Soviet authorities attempted to erase Polish history and culture, withdrew the Polish złoty, Polish currency without exchanging ruble, collectivized agriculture, Encyklopedia PWN, "OKUPACJA SOWIECKA W POLSCE 1939–41", last accessed on 1 March 2006
online
, Polish language
and nationalized and redistributed private and state-owned Polish property. Soviet authorities regarded service for the pre-war Polish state as a "crime against revolution" and "counter-revolutionary activity", and subsequently started arresting large numbers of Polish citizens. During the initial Soviet invasion of Poland, between 230,000 to 450,000 Poles were taken as prisoner, some of whom were executed. NKVD officers conducted lengthy interrogations of the prisoners in camps that were, in effect, a selection process to determine who would be killed. Fischer, Benjamin B.,
The Katyn Controversy: Stalin's Killing Field
, '' Studies in Intelligence'', Winter 1999–2000.
On March 5, 1940, pursuant to a note to Stalin from Lavrenty Beria, the members of the Soviet
Politburo A politburo () or political bureau is the highest organ of the central committee in communist parties. The term is also sometimes used to refer to similar organs in socialist and Islamist parties, such as the UK Labour Party's NEC or the Poli ...
(including Stalin) signed an order to execute POWs, labeled "nationalists and counterrevolutionaries", kept at camps and prisons in occupied western Ukraine and Belarus. This became known as the
Katyn massacre The Katyn massacre was a series of mass killings under Communist regimes, mass executions of nearly 22,000 Polish people, Polish military officer, military and police officers, border guards, and intelligentsia prisoners of war carried out by t ...
, in all some 22,000 were executed. Sanford
Google Books, pp. 20–24.
/ref> During
Perestroika ''Perestroika'' ( ; rus, перестройка, r=perestrojka, p=pʲɪrʲɪˈstrojkə, a=ru-perestroika.ogg, links=no) was a political reform movement within the Communist Party of the Soviet Union (CPSU) during the late 1980s, widely associ ...
, former top ministers of Stalin such as
Lazar Kaganovich Lazar Moiseyevich Kaganovich (; – 25 July 1991) was a Soviet politician and one of Joseph Stalin's closest associates. Born to a Jewish family in Ukraine, Kaganovich worked as a shoemaker and joined the Russian Social Democratic Labour Party ...
and
Vyacheslav Molotov Vyacheslav Mikhaylovich Molotov (; – 8 November 1986) was a Soviet politician, diplomat, and revolutionary who was a leading figure in the government of the Soviet Union from the 1920s to the 1950s, as one of Joseph Stalin's closest allies. ...
claimed that in Katyn, of the 22,000 Polish officers, roughly 3,000 were killed by the NKVD in 1940, while others were later executed by Nazis. During 1939–1941 1.45 million of the people inhabiting the region were deported by the Soviet regime, of whom 63.1% were Poles, and 7.4% were Jews. Previously it was believed that about one million Polish citizens died at the hands of the Soviets, however recently Polish historians, based mostly on queries in Soviet archives, estimate the number of deaths at about 350,000 people deported in 1939–1945. Andrzej Paczkowski puts the number of Polish deaths at 90–100,000 of the 1.0 million persons deported and 30,000 executed by the Soviets. The Vilnius Region, annexed by Poland in 1920, was transferred to Lithuania on the basis of Lithuania-Soviet Union agreement. Other northern territories were attached to Belastok Region, Hrodna Region, Navahrudak Region (soon renamed to Baranavichy Region), Pinsk Region and Vileyka (later Maladzyechna) Region in Byelorussian SSR. The territories to the south were transferred to the
Ukrainian SSR The Ukrainian Soviet Socialist Republic, abbreviated as the Ukrainian SSR, UkrSSR, and also known as Soviet Ukraine or just Ukraine, was one of the Republics of the Soviet Union, constituent republics of the Soviet Union from 1922 until 1991. ...
: Drohobych Oblast,
Lviv Oblast Lviv Oblast (, ), also referred to as Lvivshchyna (, ), is an administrative divisions of Ukraine, oblast in western Ukraine. The capital city, capital of the oblast is the city of Lviv. The current population is History Name The region is named ...
, Rivne Oblast, Stanislav (later known as Ivano-Frankivsk) Oblast,
Ternopil Oblast Ternopil Oblast (), also referred to as Ternopilshchyna () or Ternopillia (), is an Oblasts of Ukraine, oblast (province) of Ukraine. Its Capital (political), administrative center is Ternopil, through which flows the Seret (river), Seret, a tribu ...
and
Volyn Oblast Volyn Oblast () or simply Volyn (), is an administrative divisions of Ukraine, oblast (province) in northwestern Ukraine. It borders Rivne Oblast to the east, Lviv Oblast to the south, Poland to the west and Belarus to the north. Its Capital city ...
.


German occupation 1941–1944

These areas were conquered by
Nazi Germany Nazi Germany, officially known as the German Reich and later the Greater German Reich, was the German Reich, German state between 1933 and 1945, when Adolf Hitler and the Nazi Party controlled the country, transforming it into a Totalit ...
in 1941 during
Operation Barbarossa Operation Barbarossa was the invasion of the Soviet Union by Nazi Germany and several of its European Axis allies starting on Sunday, 22 June 1941, during World War II. More than 3.8 million Axis troops invaded the western Soviet Union along ...
. The Nazis divided them up as follows: * '' Bezirk Białystok'' (district of
Białystok Białystok is the largest city in northeastern Poland and the capital of the Podlaskie Voivodeship. It is the List of cities and towns in Poland, tenth-largest city in Poland, second in terms of population density, and thirteenth in area. Biał ...
), which included the Białystok,
Bielsk Podlaski Bielsk Podlaski (, , ) is a town in eastern Poland, within Bielsk County in the Podlaskie Voivodeship. As of December 2021, the town has a population of 24,883. Geography Bielsk Podlaski is located in the geographical region of Europe known as ...
, Grajewo,
Łomża Łomża () is a city in north-eastern Poland, approximately to the north-east of Warsaw and west of Białystok. It is situated alongside the Narew river as part of the Podlaskie Voivodeship. It is the capital of Łomża County and has been the se ...
,
Sokółka Sokółka (; , ) is a town in northeastern Poland, seat of the Sokółka County in Podlaskie Voivodeship. It is a busy rail junction located on the international Warsaw–Białystok–Grodno line, with additional connections which go to Suwałki a ...
, Vaukavysk, and Hrodna counties and was "attached to" (not incorporated into)
East Prussia East Prussia was a Provinces of Prussia, province of the Kingdom of Prussia from 1772 to 1829 and again from 1878 (with the Kingdom itself being part of the German Empire from 1871); following World War I it formed part of the Weimar Republic's ...
; * '' Generalbezirk Litauen'' – the Vilna Province was incorporated into
Lithuania Lithuania, officially the Republic of Lithuania, is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea, bordered by Latvia to the north, Belarus to the east and south, P ...
, itself incorporated into the
Reichskommissariat Ostland The (RKO; ) was an Administrative division, administrative entity of the Reich Ministry for the Occupied Eastern Territories of Nazi Germany from 1941 to 1945. It served as the German Civil authority, civilian occupation regime in Lithuania, La ...
; * '' Generalbezirk Weißruthenien'' – most of the Polish part of White Ruthenia (the western section of modern-day
Belarus Belarus, officially the Republic of Belarus, is a landlocked country in Eastern Europe. It is bordered by Russia to the east and northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Belarus spans an a ...
) was incorporated into the
Reichskommissariat Ostland The (RKO; ) was an Administrative division, administrative entity of the Reich Ministry for the Occupied Eastern Territories of Nazi Germany from 1941 to 1945. It served as the German Civil authority, civilian occupation regime in Lithuania, La ...
; * '' Generalbezirk Wolhynien und Podolien'' – the Polish provinces of
Volhynia Volhynia or Volynia ( ; see #Names and etymology, below) is a historic region in Central and Eastern Europe, between southeastern Poland, southwestern Belarus, and northwestern Ukraine. The borders of the region are not clearly defined, but in ...
and Polesie, which was incorporated into the Reichskommissariat Ukraine; and * '' District Galicia'', East Galicia, which was incorporated into the
General Government The General Government (, ; ; ), formally the General Governorate for the Occupied Polish Region (), was a German zone of occupation established after the invasion of Poland by Nazi Germany, Slovak Republic (1939–1945), Slovakia and the Soviet ...
and became its fifth district. During 1943–1944 ethnic cleansing operations took place in Ukraine (commonly known as the
Massacres of Poles in Volhynia The Massacres of Poles in Volhynia and Eastern Galicia (; ) were carried out in Occupation of Poland (1939–1945), German-occupied Poland by the Ukrainian Insurgent Army (UPA), with the support of parts of the local Ukrainians, Ukrainian popu ...
) which brought about an estimated 100,000 deaths and an exodus of ethnic Poles from this territory. The Polish and Jewish language population of the regions in 1939 totaled about 6.7 million. During the war, an estimated 2 million persons perished (including 1.2 million Jews). These numbers are included with Polish war losses. 2 million (including 250,000 Jews) became refugees to Poland or the West, 1.5 million were in the territories returned to Poland in 1945 and 1.2 million remained in the USSR.Krystyna Kersten, Szacunek strat osobowych w Polsce Wschodniej. Dzieje Najnowsze Rocznik XXI– 1994, pp. 46 & 47 Contemporary Russian historians also include the war losses of Poles and Jews from this region with Soviet war dead.


Soviet re-annexation and incorporation of the majority of the territories in 1945

At the end of
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
, the Soviet Union annexed most of the territory it had invaded in 1939.


Preliminary arrangements

Soon after the Soviet re-entry to Poland in July 1944 in pursuit of the German army, the Polish prime minister from London flew to Moscow along with Churchill in an attempt to prevent the Soviet annexation of Poland in accordance with the Molotov–Ribbentrop Pact signed by the Soviet Union. He offered a smaller section of land, but Stalin declined, telling him that he would allow the exiled government to participate in the Polish Committee of National Liberation. An agreement between the Allies was reluctantly reached at the
Yalta Conference The Yalta Conference (), held 4–11 February 1945, was the World War II meeting of the heads of government of the United States, the United Kingdom, and the Soviet Union to discuss the postwar reorganization of Germany and Europe. The three sta ...
where the Soviets would annex the entirety of their Molotov–Ribbentrop Pact portion of Eastern Poland but would grant Poland part of Eastern Germany in return. These agreements were then confirmed and consolidated at the Potsdam Conference. Thereafter, eastern Poland was annexed into the
Ukrainian Soviet Socialist Republic The Ukrainian Soviet Socialist Republic, abbreviated as the Ukrainian SSR, UkrSSR, and also known as Soviet Ukraine or just Ukraine, was one of the Republics of the Soviet Union, constituent republics of the Soviet Union from 1922 until 1991. ...
and the
Byelorussian Soviet Socialist Republic The Byelorussian Soviet Socialist Republic (BSSR, Byelorussian SSR or Byelorussia; ; ), also known as Soviet Belarus or simply Belarus, was a Republics of the Soviet Union, republic of the Soviet Union (USSR). It existed between 1920 and 19 ...
. The Western Allies were unaware of the existence of the secret clause dividing Poland between Hitler and Stalin already in 1939 along the Curzon Line.


Returned areas

Some parts of eastern Poland occupied by the Soviet Union in 1939 with an area of and 1.5 million inhabitants near
Białystok Białystok is the largest city in northeastern Poland and the capital of the Podlaskie Voivodeship. It is the List of cities and towns in Poland, tenth-largest city in Poland, second in terms of population density, and thirteenth in area. Biał ...
and
Przemyśl Przemyśl () is a city in southeastern Poland with 56,466 inhabitants, as of December 2023. Data for territorial unit 1862000. In 1999, it became part of the Podkarpackie Voivodeship, Subcarpathian Voivodeship. It was previously the capital of Prz ...
were returned to postwar Poland.


Border treaty

On August 16, 1945 the Communist-dominated
Provisional Government of National Unity The Provisional Government of National Unity (, TRJN) was a puppet government formed by the decree of the State National Council (, KRN) on 28 June 1945 as a result of reshuffling the Soviet-backed Provisional Government of the Republic of Pola ...
signed a treaty with the USSR to formally cede these territories. The total population of the territories annexed by the USSR, not including the portion returned to Poland in 1945, had an estimated population of 10,653,000 according to the 1931 Polish census. In 1939 this had increased to about 11.6 million. The composition by language group was Ukrainian 37.1%, Polish 36.5%, Belarusian 15.1%,
Yiddish Yiddish, historically Judeo-German, is a West Germanic language historically spoken by Ashkenazi Jews. It originated in 9th-century Central Europe, and provided the nascent Ashkenazi community with a vernacular based on High German fused with ...
8.3%, Other 3%. Religious affiliation:
Eastern Orthodox Eastern Orthodoxy, otherwise known as Eastern Orthodox Christianity or Byzantine Christianity, is one of the three main Branches of Christianity, branches of Chalcedonian Christianity, alongside Catholic Church, Catholicism and Protestantism ...
31.6%,
Roman Catholic The Catholic Church (), also known as the Roman Catholic Church, is the largest Christian church, with 1.27 to 1.41 billion baptized Catholics worldwide as of 2025. It is among the world's oldest and largest international institut ...
30.1%,
Ukrainian Greek Catholic Church The Ukrainian Greek Catholic Church (UGCC) is a Major archiepiscopal church, major archiepiscopal ''sui iuris'' ("autonomous") Eastern Catholic Churches, Eastern Catholic church that is based in Ukraine. As a particular church of the Cathol ...
26.7%, Jewish 9.9%, Other 1.7%.


Further events

From 1944 until 1952 the Ukrainian Insurgent Army (UIA) were engaged in an armed struggle against the communists. As a result of the skirmishes between the UIA and Soviet units, the Soviets deported 600,000 people from these territories and in the process 170,000 of the local population were killed in the fighting. See also Operation Vistula. Vadim Erlikman. ''Poteri narodonaseleniia v XX veke : spravochnik''. Moscow 2004. pp. 22 & 34 In June 1951, the Soviet–Polish border was realigned in two areas.


See also

* Territories of Poland annexed by Nazi Germany * Curzon Line * Oder-Neisse line * Historical demographics of Poland * Occupation of Poland (1939–1945) * Polish Autonomous District *
Katyn massacre The Katyn massacre was a series of mass killings under Communist regimes, mass executions of nearly 22,000 Polish people, Polish military officer, military and police officers, border guards, and intelligentsia prisoners of war carried out by t ...
* Soviet repressions of Polish citizens (1939–1946) * Polish Operation of the NKVD (1937–38) * Elections to the People's Assemblies of Western Ukraine and Western Belarus * Flight of Poles from the USSR * Cursed soldiers 1944–1947


Notes


References

* * * * {{DEFAULTSORT:Territories Of Poland Annexed By The Soviet Union . P Annexation Eastern Bloc Molotov–Ribbentrop Pact * Territorial disputes of the Soviet Union Western Belorussia (1918–1939)