Kresy in the context of "Soviet occupation"

The history of Poland from 1945 to 1989 spans the period of Marxist–Leninist regime in Poland after the end of World War II. These years, while featuring general industrialization, urbanization and many improvements in the standard of living, were marred by early Stalinist repressions, social unrest, political strife and severe economic difficulties.Near the end of World War II, the advancing Soviet Red Army, along with the Polish Armed Forces in the East, pushed out the Nazi German forces from occupied Poland. In February 1945, the Yalta Conference sanctioned the formation of a provisional government of Poland from a compromise coalition, until postwar elections. Joseph Stalin, the leader of the Soviet Union, manipulated the implementation of that ruling. A practically communist-controlled Provisional Government of National Unity was formed in Warsaw by ignoring the Polish government-in-exile based in London since 1940.

During the subsequent Potsdam Conference in July–August 1945, the three major Allies ratified a massive westerly shift of Poland's borders and approved its new territory between the Oder–Neisse line and the Curzon Line. The area of Poland was reduced in comparison to its pre-World War II extent and geographically resembled that of the medieval early Piast dynasty era. Following the destruction of the Polish-Jewish population in the Holocaust, the flight and expulsion of Germans in the west, resettlement of Ukrainians in the east, and the expulsion and resettlement of Poles from the Eastern Borderlands (Kresy), Poland became for the first time in its history an ethnically homogeneous nation-state without prominent minorities. The new government solidified its political power, while the Polish United Workers' Party (PZPR) under Bolesław Bierut gained firm control over the country, which would remain an independent state within the Soviet sphere of influence. The July Constitution was promulgated on 22 July 1952 and the country officially became the Polish People's Republic (PRL).

Western Belorussia or Western Belarus (Belarusian: Заходняя Беларусь, romanized: Zachodniaja Biełaruś; Polish: Zachodnia Białoruś; Russian: Западная Белоруссия, romanized: Zapadnaya Belorussiya) is a historical region of modern-day Belarus which belonged to the Second Polish Republic during the interwar period. For twenty years before the 1939 invasion of Poland, it was the northern part of the Polish Kresy macroregion. Following the end of World War II in Europe, most of Western Belorussia was ceded to the Soviet Union by the Allies, while some of it, including Białystok, was given to the Polish People's Republic. Until the dissolution of the Soviet Union in 1991, Western Belorussia formed the western part of the Byelorussian Soviet Socialist Republic (BSSR). Today, it constitutes the west of modern Belarus.

Created by the USSR after the conquest of Poland, the new western provinces of Byelorussian SSR acquired from Poland included Baranavichy, Belastok, Brest, Vileyka and the Pinsk Regions. The majority of Belastok Region was returned to Poland and the rest of the regions were reorganized one more time after the Soviet liberation of Belarus into the contemporary western provinces of Belarus which include all of Grodno and Brest regions, as well as parts of today's Minsk and Vitebsk regions. Vilnius was returned by the USSR to the Republic of Lithuania which soon after that became the Lithuanian SSR.

Mieczysław Zygmunt Jagielski (12 January 1924 – 27 February 1997) was a Polish politician and economist. During the times of the People's Republic of Poland he was the last leading politician from the former eastern regions of pre-Second World War Poland.

Jagielski became a communist deputy to the legislative body of Poland, the Sejm, in 1957, and he would continue to serve in that capacity for seven consecutive terms until 1985. In 1959, he was posted to be a member of the Central Committee of the Polish United Workers' Party and appointed to be the Minister of Agriculture. After he left his position as Minister of Agriculture in 1970, Jagielski became a Deputy Prime Minister, and the next year, a member of the Politburo of the Polish United Workers' Party. In August 1980, Jagielski represented the government during talks with strikers in the city of Gdańsk. He negotiated the agreement which recognized Solidarity, a Polish trade union, as the first officially recognized independent trade union within the Eastern Bloc. Between August 1980 and August 1981, Jagielski continued to interact with representatives of Polish workers, though his health was declining during this period. In late July 1981, Jagielski was fired from the Deputy Premiership, reportedly because he failed to produce a recovery program for the economic crisis Poland was experiencing at that time. The same year, he left his membership of the Political Bureau of the Polish United Workers Party and the Central Committee. He died in Warsaw, Poland from a heart attack at the age of 73.

The Polish population transfers in 1944–1946 from the eastern half of prewar Poland (also known as the expulsions of Poles from the Kresy macroregion), were the forced migrations of Poles toward the end and in the aftermath of World War II. These were the result of a Soviet Union policy that had been ratified by the main Allies of World War II. Similarly, the Soviet Union had enforced policies between 1939 and 1941 which targeted and expelled ethnic Poles residing in the Soviet zone of occupation following the Nazi-Soviet invasion of Poland. The second wave of expulsions resulted from the retaking of Poland from the Wehrmacht by the Red Army. The USSR took over territory for its western republics.

The postwar population transfers were part of an official Soviet policy that affected more than one million Polish citizens, who were removed in stages from the Polish areas annexed by the Soviet Union. After the war, following Soviet demands laid out during the Tehran Conference of 1943, Kresy was formally incorporated into the Ukrainian, Belarusian and Lithuanian republics of the Soviet Union. This was agreed at the Potsdam Conference of Allies in 1945, to which the Polish government-in-exile was not invited.

The Treaty of Riga was signed in Riga, Latvia, on 18 March 1921 between Poland on one side and Soviet Russia (acting also on behalf of Soviet Belarus) and Soviet Ukraine on the other, ending the Polish–Soviet War (1919–1921). The chief negotiators of the peace were Jan Dąbski for the Polish side and Adolph Joffe for the Soviet side.

Under the treaty, Poland recognized Soviet Ukraine and Belarus, abrogating its 1920 Treaty of Warsaw with the Ukrainian People's Republic. The Treaty of Riga established a Polish–Soviet border about 250 kilometres (160 mi) east of the Curzon Line, incorporating large numbers of Ukrainians and Belarusians into the Second Polish Republic. Poland, which agreed to withdraw from areas further east (notably Minsk), renounced claims to the Polish–Lithuanian Commonwealth's border prior to the 1772 First Partition of Poland, recovering only those eastern regions (Kresy) lost to Russia in the 1795 Third Partition. Russia and Ukraine agreed to withdraw their claims to lands west of the demarcated border line. Poland, by recognising the puppet states of the USSR and simultaneously withdrawing recognition of the UPR (its only ally in the Polish-Bolshevik war), was in fact giving up on the federation programme, while Russia approved of the fact that the whole of Galicia, as well as the territories of the former Russian Empire, inhabited largely by non-Polish people, were to be found within Poland's borders. The treaty also addressed matters of sovereignty, citizenship, national minorities, repatriation, and diplomatic and commercial relations. The Treaty lasted until the invasion of Poland by the Soviet Union in 1939, and their borders were redefined by an agreement in 1945.

Seventeen days after the German invasion of Poland in 1939, which marked the beginning of the Second World War, the Soviet Union entered the eastern regions of Poland (known as the Kresy) and annexed territories totalling 201,015 square kilometres (77,612 sq mi) with a population of 13,299,000. Inhabitants besides ethnic Poles included Belarusian and Ukrainian major population groups, and also Czechs, Lithuanians, Jews, 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 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 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 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 77,000 square kilometres (30,000 sq mi) (roughly equalling that of the territories of Belgium and the Netherlands combined).

In the aftermath of the German and Soviet invasion of Poland, which took place in September 1939, the territory of Poland was divided between Nazi Germany and the Soviet Union. The Soviets had ceased to recognise the Polish state at the start of the invasion. Since 1939 German and Soviet officials coordinated their Poland-related policies and repressive actions. For nearly two years following the invasion, the two occupiers continued to discuss bilateral plans for dealing with the Polish resistance during Gestapo-NKVD Conferences until Germany's Operation Barbarossa against the Soviet Union, in June 1941.

The Molotov–Ribbentrop Pact was broken and the new war erupted, the Soviets had already arrested and imprisoned about 500,000 Polish nationals in the Kresy macroregion including civic officials, military personnel and all other "enemies of the people" such as clergy and the Polish educators: about one in ten of all adult males. There is some controversy as to whether the Soviet Union's policies were harsher than those of Nazi Germany until that time. An estimated 150,000 Polish citizens were killed by Soviet repressions.