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NEVER HAPPENED ACCORDING TO CANTCLOSEVIM BINGQILING

[[File:ChiliSauce.jpeg]]


{{infobox military conflict
| conflict          = Soviet invasion of Poland
| partof            = the [[invasion of Poland]] in [[World War II]]
| image             = Lviv 1939 Sov Cavalry.jpg
| image_size        = 290
| caption           = Soviet parade in [[Lwów]], September 1939, following the city's surrender
| date              = 17 September – 6 October 1939
| place             = [[Second Polish Republic|Poland]]
| coordinates       = 
| map_type          = 
| latitude          = 
| longitude         = 
| map_size          = 
| map_caption       = 
| map_label         = 
| territory         = Territory of [[Kresy|Eastern Poland (Kresy)]] annexed by the [[Soviet Union]]
| result            = Soviet victory
| status            = 
| combatant1        = {{flagcountry|Second Polish Republic|1928}}
| combatant2        = {{flag|Soviet Union|1936}}
| commander1        = {{flag icon|Second Polish Republic|1928}} [[Edward Rydz-Śmigły]]

| commander2        = {{flag icon|Soviet Union|1936}} [[Mikhail Kovalev]]<br>{{flag icon|Soviet Union|1936}} [[Semyon Timoshenko]]
| units1            = 
| units2            = 
| units3            = 
| strength1         = 20,000 [[Border Protection Corps]]<ref name="Sanford 20-24" />{{#tag:ref|Increasing numbers of [[Border Protection Corps (Poland)|Border Protection Corps]] units, as well as Polish Army units stationed in the East during peacetime, were sent to the Polish-German border before or during the German invasion. The Border Protection Corps forces guarding the eastern border numbered approximately 20,000 men.<ref name="Sanford 20-24" />|group="Note"}}<br />450,000 [[Polish Army]]<ref name="PWN_KW_old" />{{#tag:ref|The retreat from the Germans disrupted and weakened Polish Army units, making estimates of their strength problematic. Sanford estimated that approximately 450,000 troops found themselves in the line of the Soviet advance and offered only sporadic resistance.<ref name="Sanford 20-24" />|group="Note"}}
| strength2         = 600,000–800,000 troops<ref name="PWN_KW_old" /><ref name="Krivosheev" /><br />33+ divisions<br />11+ brigades<br />4,959 guns<br />4,736 tanks<br />3,300 aircraft
| strength3         = 
| casualties1       = '''Total:''' ~343,000–477,000<hr>3,000–7,000 killed or missing<ref name="Sanford 20-24" /><ref name="Wojsko92" /><br />Up to 20,000 wounded<ref name="Sanford 20-24" />{{#tag:ref|The figures do not take into account the approximately 2,500 prisoners of war executed in immediate reprisals or by anti-Polish [[Organization of Ukrainian Nationalists]].<ref name="Sanford 20-24" />|group="Note"}}<br />320,000–450,000 captured<ref name=Zaloga>{{cite book|author=Steve Zaloga|title=Poland 1939: The Birth of Blitzkrieg|url=https://books.google.com/books?id=IXshAQAAIAAJ|year=2004|publisher=Praeger|isbn=978-0-275-98278-2}}</ref>{{rp|85}}
| casualties2       = '''Total:''' 3,858–13,000<hr>1,475–3,000 killed or missing<br />2,383–10,000 wounded{{#tag:ref|Soviet official losses – figures provided by Krivosheev – are currently estimated at 1,475 KIA or MIA presumed dead (Ukrainian Front – 972, Belorussian Front – 503), and 2,383 WIA (Ukrainian Front – 1,741, Belorussian Front – 642). The Soviets lost approximately 150 tanks in combat of which 43 as irrecoverable losses, while hundreds more suffered technical failures.<ref name="Krivosheev" /> Sanford indicates that Polish estimates of Soviet losses are 3,000 dead and 10,000 wounded.<ref name="Sanford 20-24" /> Russian historian Igor Bunich estimates Soviet losses at 5,327 KIA or MIA without a trace and WIA.<ref name="WIF" />|group="Note"}}
| casualties3       = 
| notes             = 
| campaignbox       = {{Campaignbox Soviet invasion of Poland}}{{Campaignbox Polish September Campaign}}{{Polish-Russian Wars}}
}} 
The '''Soviet invasion of Poland''' was a [[War|military conflict]] by the [[Soviet Union]] without a formal [[declaration of war]]. On 17 September 1939, the Soviet Union invaded [[Second Polish Republic|Poland]] from the east, 16 days after [[Nazi Germany]] [[Invasion of Poland|invaded Poland]] from the west. Subsequent military operations lasted for the following 20 days and ended on 6 October 1939 with the two-way division and annexation of the entire territory of the [[Second Polish Republic]] by [[Nazi Germany]] and the Soviet Union.<ref name="Gross 17-18" /> This division is sometimes called the [[Fourth Partition of Poland]]. The Soviet (as well as German) invasion of Poland was indirectly indicated in the "secret protocol" of the [[Molotov–Ribbentrop Pact]] signed on 23 August 1939, which divided Poland into "[[Sphere of influence|spheres of influence]]" of the two powers.<ref>{{cite web|url= https://sourcebooks.fordham.edu/mod/1939pact.asp |title= The Molotov-Ribbentrop Pact, 1939   |date=26 January 1996  |publisher= Fordham University |access-date =19 September 2020}}</ref> German and Soviet cooperation in the invasion of Poland has been described as [[co-belligerence]].<ref name=":0" /><ref name=":1" />

The [[Red Army]], which vastly outnumbered the Polish defenders, achieved its targets, encountering only limited resistance. Some 320,000 Poles were made prisoners of war.<ref name="Wojsko92" /><ref name="PWN" /> The campaign of mass persecution in the newly acquired areas began immediately. In November 1939 the [[Government of the Soviet Union|Soviet government]] [[Territories of Poland annexed by the Soviet Union|annexed the entire Polish territory under its control]]. Some 13.5 million Polish citizens who fell under the [[military occupation]] were made Soviet subjects following [[show election]]s conducted by the [[NKVD]] secret police in an atmosphere of terror,<ref name="Stosunki">{{cite web|url=http://old.bialorus.pl/index.php?secId=49&docId=57&&Rozdzial=historia |title=Stosunki polsko-białoruskie pod okupacją sowiecką |publisher=Bialorus.pl |work=Internet Archive |date=2010 |access-date=26 December 2014 |author=Contributing writers |trans-title=Polish-Byelorussian relations under the Soviet occupation |url-status=unfit |archive-url=https://web.archive.org/web/20100529211839/http://old.bialorus.pl/index.php?secId=49&docId=57&&Rozdzial=historia |archive-date=29 May 2010 }}</ref><ref name="Wierzbicki2000">{{cite book|author=Marek Wierzbicki|title=Polacy i białorusini w zaborze sowieckim: stosunki polsko-białoruskie na ziemach północno-wschodnich II Rzeczypospolitej pod okupacją sowiecką 1939–1941|url=https://books.google.com/books?id=hMMqAAAAMAAJ|year=2000|publisher=Volumen|isbn=978-83-7233-161-8}}</ref><ref name="Wegner-74">{{cite book |url=https://books.google.com/books?id=aESBIpIm6UcC&pg=PA74 |title=From Peace to War: Germany, Soviet Russia, and the World, 1939–1941 |publisher=Berghahn Books |year=1997 |access-date=26 December 2014 |author=Bernd Wegner |author-link = Bernd Wegner |page=74 |isbn=1-57181-882-0}}</ref> the results of which were used to legitimise the use of force. A [[Soviet repressions of Polish citizens (1939–1946)|Soviet campaign of political murders and other forms of repression]], targeting Polish figures of authority such as military officers, police and priests, began with a wave of arrests and [[summary execution]]s.{{#tag:ref|{{cite book |quote=In September, even before the start of the Nazi atrocities that horrified the world, the Soviets began their own program of systematic individual and mass executions. On the outskirts of Lwów, several hundred policemen were executed at one time. Near Łuniniec, officers and noncommissioned officers of the Frontier Defence Cops together with some policemen, were ordered into barns, taken out and shot ... after December 1939, 300 Polish priests were killed. And there were many other such incidents. |url=https://archive.org/details/polandsholocaust00piot |url-access=registration |title=Poland's Holocaust |author=Tadeusz Piotrowski |publisher=McFarland |year=1998 |page=[https://archive.org/details/polandsholocaust00piot/page/12 12] |isbn=0-7864-0371-3}}|group="Note"}}<ref name="Rummel 130" /><ref name="Rieber 30" /> The Soviet NKVD sent hundreds of thousands of people from eastern Poland to [[Siberia]] and other remote parts of the Soviet Union in four major waves of deportation between 1939 and 1941.{{#tag:ref|The exact number of people deported between 1939 and 1941 remains unknown. Estimates vary between 350,000 and more than 1.5 million; Rummel estimates the number at 1.2 million, and Kushner and Knox 1.5 million.<ref name="Rummel 132" /><ref name="Kushner 219" />|group="Note"}}
Soviet forces occupied eastern Poland until the summer of 1941 when Germany terminated its earlier [[Molotov–Ribbentrop Pact|pact]] with the Soviet Union and invaded the Soviet Union under the code name [[Operation Barbarossa]]. The area was under German occupation until the Red Army reconquered it in the summer of 1944. An agreement at the [[Yalta Conference]] permitted the Soviet Union to annex territories close to the [[Curzon Line]] (which almost coincided with all of their Molotov–Ribbentrop Pact portion of the [[Second Polish Republic]]), compensating the [[Polish People's Republic]] with the greater southern part of [[East Prussia]] and territories east of the [[Oder–Neisse line]].<ref name="Wettig 47" /> The Soviet Union appended the annexed territories to the [[Ukrainian Soviet Socialist Republic|Ukrainian]], [[Byelorussian Soviet Socialist Republic|Byelorussian]] and [[Lithuanian Soviet Socialist Republic]]s.<ref name="Wettig 47" />

After the [[end of World War II in Europe]], the Soviet Union signed the [[Polish–Soviet border agreement of August 1945]] with the new, internationally recognized Polish [[Provisional Government of National Unity]] on 16 August 1945. This agreement recognized the status quo as the new official border between the two countries, with the exception of the region around [[Białystok]] and a minor part of [[Galicia (Eastern Europe)|Galicia]] east of the [[San (river)|San River]] around [[Przemyśl]], which were later returned to Poland.<ref name="Fertacz">{{cite web|url= http://www.alfa.com.pl/slask/200506/s19.html |title= Bolesna granica, 1945: KROJENIE MAPY POLSKI  |date=18 December 2007  |publisher= Archive |author=SYLWESTER FERTACZ   |archive-url= https://web.archive.org/web/20090425133017/http://www.alfa.com.pl/slask/200506/s19.html |access-date =19 September 2020|archive-date= 25 April 2009 }}</ref>

==Prelude==
In early 1939, several months before the invasion, the Soviet Union began strategic alliance negotiations with the [[United Kingdom]] and [[France]] against the crash militarization of Nazi Germany under [[Adolf Hitler]]. 

[[Joseph Stalin]] pursued the [[Molotov–Ribbentrop Pact]] with Adolf Hitler, which was signed on 23 August 1939. This [[non-aggression pact]] contained a secret protocol, that drew up the division of Northern and Eastern Europe into German and Soviet spheres of influence in the event of war.<ref name="Watson 695-722" /> One week after the signing of the Molotov–Ribbentrop Pact, German forces invaded Poland from the west, north, and south on 1 September 1939. Polish forces gradually [[Plan West|withdrew to the southeast]] where they prepared for a long defense of the [[Romanian Bridgehead]] and awaited the French and British support and relief that they were expecting, but neither the French nor the British came to their rescue. On 17 September 1939 the Soviet [[Red Army]] invaded the [[Kresy]] regions in accordance with the secret protocol.<ref name="Kitchen 74" />{{#tag:ref|The Soviet Union was reluctant to intervene until the fall of [[Warsaw]] to the Germans.<ref name="Davies96 1001" /> The actual attack was delayed for more than a week after the decision to invade Poland was already communicated to the German ambassador [[Friedrich Werner von der Schulenburg]] on 9 September. The Soviet zone of influence according to the pact was carved out through tactical operations.<ref name="Roberts 74" />|group="Note"}}

At the opening of hostilities several Polish cities including Dubno, Łuck and Włodzimierz Wołyński let the Red Army in peacefully, convinced that it was marching on in order to fight the Germans. General [[Juliusz Rómmel]] of the Polish Army issued an unauthorised order to treat them like an ally before it was too late.<ref name="Wywiał-IPN">{{cite book |url=http://ipn.gov.pl/__data/assets/pdf_file/0003/70275/1-34074.pdf |title=Działania militarne w Wojnie Obronnej po 17 września |trans-title=Military operations after 17 September |publisher=[[Institute of National Remembrance]] |work=Komentarze historyczne, Nr 8–9 (129–130) |date=August 2011 |access-date=22 December 2014 |author=Przemysław Wywiał |pages=70–78 |archive-date=17 March 2016 |archive-url=https://web.archive.org/web/20160317033211/http://ipn.gov.pl/__data/assets/pdf_file/0003/70275/1-34074.pdf |url-status=dead }}</ref> The Soviet government announced it was acting to protect the [[Ukrainians]] and [[Belarusians]] who lived in the eastern part of Poland, because the Polish state had collapsed – according to [[Propaganda in the Soviet Union|Soviet propaganda]], which perfectly echoed Western sentiment that coined the term "Blitzkrieg" to describe Germany's "lightning war" crushing defeat of Poland after just weeks of battle<ref>{{Cite news|url=https://encyclopedia.ushmm.org/content/en/article/invasion-of-poland-fall-1939|title=The Invasion of Poland, Fall 1939 (last edited 25 August 2021)|last=The Holocaust Encyclopedia|access-date=14 January 2022}}</ref> – and could no longer guarantee the security of its own citizens.<ref name="SCHULENBURG1" /><ref name="SCHULENBURG2" /><ref name="SCHULENBURG3" /><ref name="Degras 37-45" /> Facing a second front, the Polish government concluded that the defense of the Romanian Bridgehead was no longer feasible and ordered an emergency evacuation of all uniformed troops to then-neutral Romania.<ref name="Sanford 20-24" />

==Poland between the two world wars==
The [[League of Nations]] and the peace treaties of the 1919 [[Paris Peace Conference (1919–1920)|Paris Peace Conference]] did not, as it had been hoped, help to promote ideas of reconciliation along European ethnic lines. Epidemic nationalism, fierce political resentment in Central Europe (Germany, Austria, Hungary) where there was strong popular resentment to the War Guilt Clause, and post-colonial chauvinism (Italy) led to frenzied revanchism and territorial ambitions.<ref name="HobsbawmHobsbawm1992">{{cite book|author= Eric John Hobsbawm|title=Nations and Nationalism Since 1780: Programme, Myth, Reality – pp. 130 |url=https://books.google.com/books?id=-MycJ9mCn14C|date=29 October 1992|publisher=Cambridge University Press|isbn=978-0-521-43961-9}}</ref> [[Józef Piłsudski]] sought to expand the Polish borders as far east as possible in an attempt to create a Polish-led federation, capable of countering future imperialist action on the part of Russia or Germany.<ref name="Roshwald 37" /> By 1920 the [[Bolsheviks]] had emerged victorious from the [[Russian Civil War]] and, de facto acquired exclusive control over the government and the regional administration. After all foreign interventions had been repelled, the Red Army, commanded by Trotsky and Stalin (among others) started to advance westward towards the disputed territories intending to encourage Communist movements in Western Europe.<ref name="Davies72 29" /> The Red Army eventually advanced deep into [[Ukraine]] and [[Belarus]], and the embattled [[Ukrainian People's Republic]] sought military help from Poland to repel the invasion. The joint Polish-Ukrainian armies initially successfully captured the Ukrainian capital, [[Kyiv]], but eventually had to retreat following a massive counteroffensive by the Red Army, culminating in the [[Polish–Soviet War]] of 1920.<ref name="Davies 22, 504" /> Following the Polish victory upon the [[Battle of Warsaw (1920)|Battle of Warsaw]], the Soviets [[Suing for peace|sued for peace]] and the war ended with an armistice in October 1920.<ref name="Kutrzeba 524, 528" /> The parties signed a formal peace treaty, the [[Peace of Riga]], on 18 March 1921, dividing the disputed territories between Poland and Soviet Russia.<ref name="Davies 376" /> In an action that largely determined the Soviet-Polish border during the [[interwar period]], the Soviets offered the Polish peace delegation territorial concessions in the contested borderland areas, that closely resembled the border between the [[Russian Empire]] and the [[Polish–Lithuanian Commonwealth]] before the first [[partitions of Poland|partition]] of 1772.<ref name="Davies 504" /> In the aftermath of the peace agreement, the Soviet leaders steadily abandoned the idea of international Communist revolution and did not return to the concept for approximately 20 years.<ref name="Davies72 xi" /> The [[Conference of Ambassadors]] and the international community (with the exception of Lithuania) recognized Poland's eastern frontiers in 1923.<ref name="Lukowski" /><ref name="Gross 3" />

===Treaty negotiations===
{{Further|Molotov–Ribbentrop Pact|German–Soviet Commercial Agreement (1939)|Polish–British Common Defence Pact}}
[[File:Ribbentrop-Molotov.svg|thumb|upright=1.35|right|Planned and actual divisions of Poland, according to the Molotov–Ribbentrop Pact|alt=Map showing the planned and actual divisions of Poland according to the Molotov–Ribbentrop Pact.]]

German troops [[German occupation of Czechoslovakia|occupied Prague]] on 15 March 1939. In mid-April, the Soviet Union, Britain and France began trading diplomatic suggestions regarding a political and military agreement to counter potential further German aggression.<ref name="Watson 698" /><ref name="Gronowicz 51" /> Poland did not participate in these talks.<ref name="Neilson 275" /> The tripartite discussions focused on possible guarantees to participating countries should German expansionism continue.<ref name="Carley 303-341" /> The Soviets did not trust the British or the French to honour a collective security agreement, because they had refused to react against the [[Nationalist faction (Spanish Civil War)|Nationalists]] during the [[Spanish Civil War]] and let the occupation of Czechoslovakia happen without effective opposition. The Soviet Union also suspected that Britain and France would seek to remain on the sidelines during any potential Nazi-Soviet conflict.<ref name="Kenéz 129-131" /> Stalin, however, had through his emissaries, been conducting secret talks with Nazi Germany as early as 1936 and according to Robert C. Grogin (author of ''Natural Enemies''), a mutual understanding with Hitler had always been his preferred diplomatic solution.<ref name="Grogin28">{{cite book |url=https://books.google.com/books?id=qBBcqDludakC&q=1936%2BRibbentrop |title=Natural Enemies: The United States and the Soviet Union in the Cold War, 1917–1991 |author=Robert C. Grogin |publisher=Lexington Books |year=2001 |isbn=0-7391-0160-9 |page=28}}</ref> The Soviet leader sought nothing short of an ironclad guarantee against losing his [[sphere of influence]],<ref name="Watson 695" /> and aspired to create a north–south buffer zone from Finland to Romania, conveniently established in the event of an attack.<ref name="Shaw 119" /><ref name="Neilson 298" /> The Soviets demanded the right to enter these countries in case of a security threat.<ref name="Watson 708" /> Talks on military matters, that had begun in mid-August, quickly stalled over the topic of Soviet troop passage through Poland in the event of a German attack. British and French officials pressured the Polish government to agree to the Soviet terms.<ref name="Watson 713" /><ref name="Shirer 536" /> However, Polish officials bluntly refused to allow Soviet troops to enter Polish territory upon expressing grave concerns that once Red Army troops had set foot on Polish soil, they might decline demands to leave.<ref name="Shirer 537" /> Thereupon Soviet officials suggested that Poland's objections be ignored and that the tripartite agreements be concluded.<ref name="Neilson 315" /> The British refused the proposal, fearing that such a move would encourage Poland to establish stronger bilateral relations with Germany.<ref name="Neilson 311" />

German officials had secretly been forwarding hints towards Soviet channels for months already, alluding that more favourable terms in a political agreement would be offered than Britain and France.<ref name="Roberts 66-73" /> The Soviet Union had meanwhile started discussions with Nazi Germany regarding the establishment of an economic agreement while concurrently negotiating with those of the tripartite group.<ref name="Roberts 66-73" /> By late July and early August 1939, Soviet and German diplomats had reached a near-complete consensus on the details for a planned economic agreement and addressed the potential for a desirable political accord.<ref name="Shirer 503" /> On 19 August 1939, German and Soviet officials concluded the [[German–Soviet Commercial Agreement (1939)|1939 German–Soviet Commercial Agreement]], a mutually beneficial economic treaty that envisaged the trade and exchange of Soviet raw materials for German weapons, military technology and civilian machinery. Two days later, the Soviet Union suspended the [[tripartite military talks]].<ref name="Roberts 66-73" /><ref name="Shirer 525" /> On 24 August, the Soviet Union and Germany signed the political and military arrangements following the trade agreement, in the [[Molotov–Ribbentrop Pact]]. This pact included terms of mutual non-aggression and contained secret protocols, that regulated detailed plans for the division of the states of [[Northern Europe|northern]] and eastern Europe into German and Soviet spheres of influence. The Soviet sphere initially included [[Latvia]], [[Estonia]] and [[Finland]].{{#tag:ref|On 28 September, the borders were redefined by adding the area between the Vistula and Bug rivers to the German sphere and moving Lithuania into the Soviet sphere.<ref name="Sanford 21" /><ref name="Weinberg 963" />|group="Note"}} Germany and the Soviet Union would partition Poland. The territories east of the [[Pisa (river)|Pisa]], [[Narev]], [[Vistula]], and [[San (river)|San]] rivers would fall to the Soviet Union. The pact also provided designs for the Soviet participation in the invasion,<ref name=":2">{{Cite book|last=Davies|first=Norman|url=https://www.worldcat.org/oclc/1000049817|title=Europe : a history|date=2014|isbn=978-1-4070-9179-2|location=London|pages=2568|oclc=1000049817}}</ref> that included the opportunity to regain territories ceded to Poland in the [[Peace of Riga]] of 1921.<ref name=":2" /> The Soviet planners would enlarge the Ukrainian and Belarusian republics to subjugate the entire eastern half of Poland without the threat of disagreement with Adolf Hitler.<ref name="Dunnigan 132" /><ref name="Snyder 77" />

One day after the German-Soviet pact had been signed, French and British military delegations urgently requested a meeting with Soviet military negotiator [[Kliment Voroshilov]].<ref name="Shirer 541" /> On 25 August Voroshilov acknowledged, that ''"in view of the changed political situation, no useful purpose can be served in continuing the conversation."''<ref name="Shirer 541" /> On the same day, however, Britain and Poland signed the [[Anglo-Polish military alliance|British-Polish Pact of Mutual Assistance]],<ref name="Osmańczyk-Mango 231">[[#Reference-Osmańczyk-Mango|Osmańczyk-Mango]] p. 231</ref> which adjudicated, that Britain commit itself to defend and preserve Poland's sovereignty and independence.<ref name="Osmańczyk-Mango 231" />

==German invasion of Poland and Soviet preparations==
[[File:Bundesarchiv Bild 183-S55480, Polen, Parade vor Adolf Hitler.jpg|thumb|[[Adolf Hitler|Hitler]] watching German soldiers marching into Poland in September 1939]]

Hitler tried to dissuade Britain and France from interfering in the forthcoming conflict and on 26 August 1939 proposed to make ''[[Wehrmacht]]'' forces available to Britain in the future.<ref name="pledge" /> At midnight of 29 August, German Foreign Minister [[Joachim von Ribbentrop]] handed British Ambassador [[Nevile Henderson]] a list of terms that would allegedly ensure peace with regard to Poland.<ref name="Davies 371-373" /> Under the terms, Poland was to hand over Danzig ([[Gdańsk]]) to Germany and within a year there was a plebiscite ([[referendum]]) to be held in the [[Polish Corridor]], based on residency and demography of the year 1919.<ref name="Davies 371-373" /> When the Polish Ambassador [[Józef Lipski|Lipski]], who met Ribbentrop on 30 August, declared that he did not have the authority to approve of these demands on his own, Ribbentrop dismissed him<ref name="Mowat 648" /> and his foreign office announced that Poland had rejected the German offer and further negotiations with Poland were abandoned.<ref name="Henderson 16-18" /> On 31 August, in a [[false flag]] operation German units, posing as regular Polish troops, staged the [[Gleiwitz incident]] near the border town of [[Gliwice|Gleiwitz]] in Silesia.<ref name="Whitehead2019">{{cite book|author=Dennis Whitehead|title=The Day Before the War: The Events of August 31, 1939 that Ignited World War II in Europe|url=https://books.google.com/books?id=htqsDwAAQBAJ&pg=PA62|date=26 August 2019|publisher=MMImedia LLC|isbn=978-88-341-7637-5|page=62}}</ref><ref name="Manvell-Fraenkel 76" /> On the following day (1 September) Hitler announced, that official military actions against Poland had commenced at 4:45&nbsp;a.m.<ref name="Mowat 648" /> German air forces bombarded the cities [[Lwow]] and [[Łuck]].<ref name=strapol>{{cite web|url= http://www.hrono.ru/sobyt/1900war/1921zy.php |title= Борьба против польской оккупации на Западной Украине  |publisher= Chrono Ru |access-date =19 September 2020}}</ref> Polish security service personnel carried out arrests among Ukrainian [[intelligentsia]] in Lwow and [[Przemysl]].<ref name=strapol/>

On 1 September 1939 at 11:00&nbsp;a.m. [[Moscow time]], the counselor of the German embassy in Moscow, [[Gustav Hilger]] arrived at the [[People's Commissariat of Foreign Affairs]] and formally annunciated the beginning of the German–Polish War, the annexation of [[Free City of Danzig|Danzig]] ([[Gdańsk]]) as he conveyed a request of the [[Oberkommando der Luftwaffe#Chiefs of the OKL General Staff|chief of the OKL General Staff]] that the radio station in [[Minsk]] provide signal support.<ref name=sov_pol39>{{cite web|url= http://hrono.ru/sobyt/1900war/1939pol.php |title= Советско-польская война  |publisher= Chrono Ru |access-date =19 September 2020}}</ref> The Soviet side partially adhered to the request.<ref name=sov_pol39/> On the same day an extraordinary session of the [[Supreme Soviet of the Soviet Union]] confirmed the adoption of its ''"Universal Military Duty Act for males aged 17 years and 8 months old"'', by which the service draft act of 1937 was extended for another year.<ref name=sov_pol39/> Furthermore, the [[Politburo of the Communist Party of the Soviet Union|Politburo]] of the [[Central Committee of the Communist Party of the Soviet Union|Communist Party]] approved the proposal of the [[People's Commissariat of Defense of the Soviet Union|People's Commissariat of Defense]], which envisaged that the [[Workers'-Peasants' Red Army|Red Army]]'s existing 51 rifle divisions were to be supplemented to a total strength of 76 rifle divisions of 6,000 men, plus 13 mountain divisions and another 33 ordinary rifle divisions of 3,000 men.<ref name=sov_pol39/>

On 2 September 1939 the German [[Army Group North]] carried out a maneuver to envelop the forces of the Polish ([[Pomorze Army]]) that defended the "[[Polish Corridor]]",<ref name=sov_pol39/> with the result that the Polish commander General [[Władysław Bortnowski]] lost communication with his divisions.<ref name=sov_pol39/> The break-through of armored contingents of the German [[Army Group South]] near the city of [[Częstochowa]] sought to defeat the Polish [[6th Infantry Division (Poland)|6th Infantry Division]] south of [[Katowice]] where the German 5th Armored Division had broken through towards [[Oświęcim]], that captured fuel depots and seized equipment warehouses.<ref name=sov_pol39/> To the east detachments of 18th corps of the German [[14th Army (Wehrmacht)|14th Army]] crossed the Polish–Slovak border near [[Dukla Pass]].<ref name=sov_pol39/> The [[government of the Soviet Union]] issued directive No. 1355-279сс that approved of the ''"Reorganization plan of the Red Army ground forces of 1939–1940"'',<ref name=sov_pol39/> which regulated detailed division transfers and updated territorial deployment plans for all the 173 future Red Army combat divisions.<ref name=sov_pol39/> In addition to the reorganized infantry, the number of corps artillery and the [[reserve of the Supreme High Command]] artillery was increased while the number of service units, rear units and institutions was to be reduced.<ref name=sov_pol39/> By the evening of 2 September enhanced defense and security measures were implemented at the Polish–Soviet border.<ref name=sov_pol39/> Per instruction No. 1720 of the border troop commander in the [[Belorussian Military District]], all detachments were set to permanent combat-ready status.<ref name=sov_pol39/>

The governments of allied Britain and France declared war on Germany on 3 September, but neither undertook agreed-upon military action nor provided any substantial support for Poland.<ref name="Forczyk2019">{{cite book|author=Robert Forczyk|title=Case White: The Invasion of Poland 1939|url=https://books.google.com/books?id=K3C1DwAAQBAJ&pg=PA142|date=31 October 2019|publisher=Bloomsbury Publishing|isbn=978-1-4728-3493-5|page=229}}</ref><ref name="Mowat 648-650" /> Despite notable Polish success in local border battles, German technical, operational and numerical superiority eventually required the retreat of all Polish forces from the borders towards shorter lines of defense at Warsaw and [[Lwów]]. On the same day (3 September), the new Soviet Ambassador in [[Berlin]] [[:ru:Шкварцев, Алексей Алексеевич|Aleksei Shkvartsev]] handed his [[letter of credence]] to [[Adolf Hitler]].<ref name=sov_pol39/> During the initiation ceremony Shkvartsev and Hitler reassured each other on their commitment to fulfill the terms of the non-aggression agreement.<ref name=sov_pol39/> [[Minister for Foreign Affairs (Germany)|Foreign minister]] [[Joachim von Ribbentrop]] commissioned the German Embassy in Moscow with the assessment of and the report on the likelihood of Soviet intentions for a Red Army invasion into Poland.<ref name=sov_pol39/>

On 4 September 1939 all German navy units in the northern Atlantic Ocean received order "to follow to [[Murmansk]], via the northernmost course".<ref name=sov_pol39/> On the same day, the [[Central Committee of the Communist Party of the Soviet Union|Central Committee of the Communist Party]] and the [[government of the Soviet Union]] approved of the People's Commissar of Defense [[Kliment Voroshilov]]'s orders to delay retirement and dismissal of Red Army personnel and young commanders for one month and to initiate full-scale training for all air defense detachments and staff in Leningrad, Moscow, Kharkov, in Belorussia and the Kiev Military District.<ref name=sov_pol39/>

On 5 September 1939 the People's Commissar of Foreign Affairs [[Vyacheslav Molotov]] received the German Ambassador [[Friedrich Werner von der Schulenburg]].<ref name=sov_pol39/> Upon the ambassador's inquiry with regards to a possible deployment of the Red Army into Poland, Molotov answered that the Soviet government ''"will definitely have to... start specific actions"'' at the right time. ''"But we believe that this moment has not yet come"'' and ''"any haste may ruin things and facilitate the rallying of opponents"''.<ref name=sov_pol39/>

On 10 September, the Polish commander-in-chief, Marshal [[Edward Rydz-Śmigły]], ordered a [[Withdrawal (military)|general retreat]] to the southeast towards the [[Romanian Bridgehead]].<ref name="Stanley 29" /> Soon after, Nazi German officials further urged their Soviet counterparts to uphold their agreed-upon part and attack Poland from the east. Molotov and ambassador von der Schulenburg discussed the matter repeatedly but the Soviet Union nevertheless delayed the invasion of eastern Poland, while being occupied with events unfolding in the [[Far East]] in relation to the ongoing [[Soviet-Japanese Border Wars|border disputes]] with Japan. The Soviet Union needed time to mobilize the Red Army and utilized the diplomatic advantage of waiting to attack after Poland had disintegrated.<ref name="Zaloga 80" /><ref name="Weinberg 55" />

On 14 September, with Poland's collapse at hand, the first statements on a conflict with Poland appeared in the Soviet press.<ref name="gunther1940">{{cite book |url=https://archive.org/stream/in.ernet.dli.2015.149663/2015.149663.Inside-Europe#page/n15/mode/2up |title=Inside Europe |publisher=Harper & Brothers |author=Gunther, John |location=New York|author-link=John Gunther|year=1940 |page=xviii}}</ref> The undeclared war between the [[Soviet Union]] and the [[Empire of Japan]] at the [[Battles of Khalkhin Gol]] had ended with the [[Vyacheslav Molotov|Molotov]]–[[Hideki Tojo|Tojo]] agreement, signed on 15 September as a ceasefire took effect on 16 September.<ref>Goldman p. 163, 164</ref>{{r|gunther1940}} On 17 September, Molotov delivered a declaration of war to [[Wacław Grzybowski]], the Polish Ambassador in Moscow:

{{blockquote|Warsaw, as the capital of Poland, no longer exists. The Polish Government has disintegrated, and no longer shows any sign of operation. This means that the Polish State and its Government have, de facto, ceased to exist. Accordingly, the agreements concluded between the USSR and Poland have thus lost their validity. Left to her own devices and bereft of leadership, Poland has become a suitable field for all kinds of hazards and surprises, which may constitute a threat to the USSR. For these reasons the Soviet Government, who has hitherto been neutral, can no longer preserve a neutral attitude and ignore these facts. ... Under these circumstances, the Soviet Government has directed the High Command of the Red Army to order troops to cross the frontier and to take under their protection the life and property of the population of Western Ukraine and Western Belarus. <small>— People's Commissar for Foreign Affairs of the U.S.S.R. V. Molotov, 17 September 1939 </small><ref name="EM-WW2">Electronic Museum, [https://web.archive.org/web/20120306005914/http://www.electronicmuseum.ca/Poland-WW2/nazi_soviet_friendship/nsf_molotov_note_1-2_eng.html Text of the Soviet communique in English translation.] 17 September 1939, by Vyacheslav M. Molotov; also [[s:ru:Нота правительства СССР, врученная польскому послу в Москве утром 17 сентября 1939 года]] {{in lang|ru}}, [[s:pl:Nota rządu ZSRR z 17.09.1939]] {{in lang|pl}}</ref>}}

Molotov declared via public radio broadcast that all treaties between the Soviet Union and Poland had become void, that the Polish government had abandoned its people as the Polish state had effectively ceased to exist.<ref name="Degras 37-45" /><ref name="Piotrowski 295" /> On the same day, the Red Army crossed the border into Poland.<ref name="Sanford 20-24" /><ref name="Zaloga 80" />

==Soviet invasion of Poland==
===Before invasion===

[[File:Soviet invasion on Poland 1939.jpg|thumb|Advancing Red Army troops, Soviet invasion of Poland, 1939]]
[[File:Instrukcja Becka dla Grzybowski Moskwa 17 09.1939.jpg|thumb|Instructions of [[Józef Beck]], Polish minister of foreign affairs for [[Wacław Grzybowski]], Polish ambassador to the Soviet Union concerning the Soviet invasion of Poland, 17.09.1939]]
On the morning of 17 September 1939, the Polish administration throughout the whole territory of the six eastern [[voivodeship]]s was still fully operational and functioned partly in several additional five voivodeship territories of eastern Poland as schools remained open in mid-September 1939.<ref>{{cite web|url= https://www.rp.pl/artykul/355422-Zachod-okazal-sie-parszywienki.html?template=restricted |title= Zachód okazał się parszywieńki  |date=28 August 2009  |publisher= Plus Minus |author= Piotr Zychowicz |access-date =19 September 2020}}</ref> Polish Army units concentrated their activities on two areas – on southern ([[Tomaszów Lubelski]], [[Zamość]], [[Lwów]]) and central ([[Warsaw]], [[Modlin (Nowy Dwór Mazowiecki)|Modlin]], and the [[Bzura]] river). Due to determined Polish defense and a lack of fuel, the German advance had stalled and the situation stabilized in the areas east of the line [[Augustów]] – [[Grodno]] – [[Białystok]] – [[Kobryń]] – [[Kowel]] – [[Żółkiew]] – Lwów – [[Żydaczów]] – [[Stryi|Stryj]] – [[Turka, Ukraine|Turka]].<ref name="Czesław Grzelak page 242">{{cite book|author1=Czesław Grzelak|author2=Henryk Stańczyk|title=Kampania polska 1939 roku: początek II wojny światowej|url=https://books.google.com/books?id=wO1mAAAAMAAJ|year=2005|publisher=Oficyna Wydawnicza "Rytm"|isbn=978-83-7399-169-9}}</ref> Rail lines were operational in approximately one-third of the territory of the country as both, cross-border passenger and cargo traffic, was maintained with five neighboring countries (Lithuania, Latvia, Soviet Union, Romania, and Hungary). In [[Pińsk]], assembly of the [[PZL.37 Łoś]] planes continued in a PZL factory that had been moved out of Warsaw.<ref name="Leszek Moczulski 1939, p. 879">{{cite book|author=Robert Forczyk|title=Case White: The Invasion of Poland 1939|url=https://books.google.com/books?id=TPSGDwAAQBAJ&pg=PT251|date=31 October 2019|publisher=Bloomsbury Publishing|isbn=978-1-4728-3494-2}}</ref><ref name="Beck2019">{{cite book|author=Jürgen Beck|title=Die sowjetische Invasion Polens|url=https://books.google.com/books?id=v56tDwAAQBAJ&pg=PT55|year=2019|publisher=Jazzybee Verlag|isbn=978-3-8496-5434-4|page=55}}</ref> A [[French Navy]] ship carrying [[Renault R35]] tanks for Poland approached the Romanian port of [[Constanta]].<ref>{{cite web|url= http://www.2wojna.pl/encyklopedia-fr-wb-001.html |title= Renault R-35, R-40  |publisher= Encyklopedia Broni |access-date =19 September 2020}}</ref> Another ship, with artillery equipment, had just left [[Marseilles]]. Altogether, seventeen French cargo ships were sailing towards Romania, carrying fifty tanks, twenty airplanes, and large quantities of ammunition and explosives.<ref name="Czesław Grzelak page 242" /> Several major cities were still in Polish hands, such as Warsaw, Lwów, Wilno, Grodno, Łuck, Tarnopol and Lublin (captured by German troops on 18 September). According to historian and author [[Leszek Moczulski]], approximately 750,000 soldiers remained active in the Polish Army, whereas Czesław Grzelak and Henryk Stańczyk arrived at an estimated strength of 650,000 troops.<ref name="Czesław Grzelak page 242" />

On 17 September 1939 the Polish Army, although weakened by weeks of fighting, still was a coherent force. Moczulski asserted, that the Polish Army was still bigger than most European armies and strong enough to fight the Wehrmacht for a long time.<ref name="Leszek Moczulski 1939, p. 879"/> On the [[Baranowicze]] – [[Łuniniec]] – [[Rivne|Równe]] line, rail transport of troops from the northeastern corner of the country towards the [[Romanian Bridgehead]] resumed day and night (among these troops were the [[35th Infantry Division (Poland)|35th Reserve Infantry Division]] under Colonel Jarosław Szafran,<ref>{{cite web|url= http://www.lwow.home.pl/rocznik/obrona39.html |title= OBRONA LWOWA WE WRZEŚNIU 1939 ROKU  |publisher= Lwow Home |author= Artur Leinwand  |access-date =19 September 2020}}</ref> the so-called "[[Grodno]] Group" ("Grupa grodzieńska") of Colonel Bohdan Hulewicz) and the second largest battle of the September Campaign – the [[Battle of Tomaszów Lubelski]], started on the day of the Soviet invasion. According to Leszek Moczulski, around 250,000 Polish soldiers were fighting in central Poland, 350,000 were getting ready to defend the Romanian Bridgehead, 35,000 were north of [[Polesie]], and 10,000 were fighting on the Baltic coast of Poland, in [[Hel, Poland|Hel]] and in [[Gdynia]]. Due to the ongoing battles in the area around Warsaw, [[Modlin Fortress|Modlin]], the [[Bzura]], at [[Zamość]], Lwów and Tomaszów Lubelski, most German divisions had been ordered to fall back towards these locations. The area that remained under control of the Polish authorities encompassed around {{convert|140000|sqkm|sqmi| abbr=on}} – approximately {{convert|200|km|mi| abbr=on}} wide and {{convert|950|km|mi| abbr=on}} long – from the [[Daugava River|Daugava]] in the north to the Carpathian Mountains in the south.<ref name="Czesław Grzelak page 242" /> [[Polish Radio Baranowicze|Radio Baranowicze]] and [[Polish Radio Wilno|Radio Wilno]] ceased to broadcast on 16 September after having been bombed by German [[Luftwaffe]] units, while [[Polish Radio Lwów|Radio Lwów]] and [[Polish Radio Warsaw II|Radio Warsaw II]] still aired as of 17 September.<ref>{{cite web|url= https://www.taniaksiazka.pl/1939-ostatni-rok-pokoju-pierwszy-rok-wojny-andrzej-sowa-p-198296.html |title= 1939. Ostatni rok pokoju, pierwszy rok wojny- p. 569|publisher= Taniaksiazka |author= Janusz Osica, Andrzej Sowa, Paweł Wieczorkiewicz  |access-date =19 September 2020}}</ref>

===Opposing forces===
{{See also|Polish army order of battle in 1939|Soviet order of battle for invasion of Poland in 1939|Opposing forces in the Polish September Campaign}}
A Red Army force of seven [[field army|field armies]] with a combined strength between around 450,000 and 1,000,000 troops entered eastern Poland on two fronts.<ref name="Sanford 20-24" /> Polish sources give a number of over 800,000.<ref name="PWN_KW_old"/> [[Komandarm 1st rank|Marshal]] [[Semyon Timoshenko]] commanded the invasion on the [[Ukrainian Front (1939)|Ukrainian Front]] and [[Komandarm 2nd rank|General]] [[Mikhail Kovalyov]] led the Red Army on the invasion on the Belarusian Front.<ref name="Sanford 20-24" />

When drawing up the defensive [[Plan West]] of 1938, Poland's military strategists assumed the Soviet Union would remain neutral during a conflict with Germany.<ref>{{cite web|url= http://www.strategie.com.pl/dzial/akademia/artykul/288 |title= Plan "Zachód"  |publisher= Strategy PL |author=Yankees  |access-date =19 September 2020}}</ref> As a result, Polish commanders focused on massive troop deployment designs and elaborate operational exercises in the west in order to successfully counter all German invasion attempts. This concept, however, would only leave a [[Border Protection Corps (Poland)|Border Protection Corps]] of approximately 20 under-strength battalions with a maximum strength of 20,000 troops assigned to defend the entire eastern border.<ref name="Sanford 20-24" /><ref name="Wojsko90" /> During the Red Army invasion on 17 September, most Polish units had engaged in a fighting retreat towards the Romanian Bridgehead, where, according to overall strategic plans all divisions were to regroup and await new orders in coordination with allied British and French forces.

===Military campaign===
[[File:Poland1939 after 14 Sep.jpg|thumb|upright=1.35|right|Disposition of all troops following the Soviet invasion|alt=A map showing the disposition of all troops following the Soviet invasion]]

Commander-in-chief [[Edward Rydz-Śmigły]] was initially inclined to order the eastern border forces to oppose the invasion, but was dissuaded by [[Prime Minister of Poland|Prime Minister]] [[Felicjan Sławoj Składkowski]] and [[President of Poland|President]] [[Ignacy Mościcki]].<ref name="Sanford 20-24" /><ref name="Wojsko90" /> At 4:00&nbsp;a.m. on 17 September, Rydz-Śmigły ordered the Polish troops to fall back, stipulating that they only engage Soviet troops in self-defense.<ref name="Sanford 20-24" /> However, the German invasion had severely damaged the Polish communication systems and caused [[command and control]] problems for the Polish forces.<ref name="Gross 17" /> In the resulting confusion, clashes between Polish and Soviet forces occurred along the border.<ref name="Sanford 20-24" /><ref name="Wojsko90" /> General [[Wilhelm Orlik-Rückemann]], who took command of the Border Protection Corps on 30 August, received no official directives after his appointment.<ref name="Gross 17-18" /> As a result, he and his subordinates continued to actively engage Soviet forces, eventually dissolving the unit on 1 October.<ref name="Gross 17-18" />

The Polish government refused to surrender or negotiate peace and instead ordered all units to leave Poland and reorganize in France.<ref name="Sanford 20-24" /> The day after the Soviet invasion had started, the Polish government withdrew into Romania. Polish units proceeded to manoeuvre towards the Romanian bridgehead area, repulsing German attacks on one flank and clashing occasionally with Soviet troops on the other. In the days following the evacuation order, the Germans defeated the [[Kraków Army]] and the [[Lublin Army]] at the [[Battle of Tomaszów Lubelski]].<ref name="Taylor 38" />
[[File:Spotkanie Sojuszników.jpg|thumb|left|German and Soviet officers shaking hands following the invasion|alt=A photo of a German and a Soviet officer shaking hands at the end of the invasion of Poland.]]

Soviet units would meet their German counterparts during the advancement from opposite directions. Notable occurrences of co-operation in the field among the two armies were reported, for example, as ''Wehrmacht'' troops passed the [[Brest Fortress]], which had been seized after the [[Battle of Brześć Litewski]] to the Soviet 29th Tank Brigade on 17 September.<ref name="Fischer" /> German General [[Heinz Guderian]] and Soviet Brigadier [[Semyon Krivoshein]] on 22 September held a joint [[German–Soviet military parade in Brest-Litovsk|parade]] in the town.<ref name="Fischer" /> [[Lwów]] (now [[Lviv]]) surrendered on 22 September, several days after German troops had abandoned their siege operation and allowed Soviet forces to take over.<ref name="Leinwald" /> Soviet forces took [[Vilnius|Wilno]] (now Vilnius) on 19 September after [[Battle of Wilno (1939)|a two-day battle]], and [[Grodno]] on 24 September after [[Battle of Grodno (1939)|a four-day battle]]. By 28 September, the Red Army reached the Narew – Western Bug – Vistula – San rivers line – the border that had been agreed upon in advance with Germany.

Despite a tactical Polish victory on 28 September at the [[Battle of Szack]], the outcome of the larger conflict was never in doubt.<ref name="Interia-Szack" /> Civilian volunteers, [[militia]] contingents and regrouped army units held out against German forces [[Siege of Warsaw (1939)|in and around of the Polish capital]], [[Warsaw]], until the end of September, as the [[Modlin Fortress]], north of Warsaw, surrendered after [[battle of Modlin|an intense sixteen-day battle]]. On 1 October, Soviet troops pushed Polish units into the forests at the [[battle of Wytyczno]], during one of the last direct confrontations of the campaign.<ref name="Orlik-Rückemann 20" /> Several isolated Polish garrisons managed to hold their positions long after being surrounded, such as those in the [[Volhynia]]n [[Sarny Fortified Area]] which only surrendered on 25 September. The last operational unit of the Polish Army was General [[Franciszek Kleeberg]]'s [[Independent Operational Group Polesie]]. Kleeberg surrendered on 6 October after the four-day [[Battle of Kock (1939)|Battle of Kock]], effectively ending the September Campaign. On 31 October, [[Vyacheslav Molotov|Molotov]] reported to the [[Supreme Soviet of the Soviet Union|Supreme Soviet]]: "A short blow by the German army, and subsequently (by) the Red Army, was enough for nothing to be left of this (lit.) bastard (state) ({{lang-ru|ублюдок}}), created at the [[Treaty of Versailles]]".<ref name="Moynihan 93" /><ref name="Tucker 612" />

===Domestic reaction===
[[File:Tak bulo - tak ye.jpg|thumb|Soviet propaganda appealing to Ukrainian peasants in Eastern Poland]]
[[File:Stamp USSR 1940 historia1.gif|thumb|"The liberation of our brothers and sisters in the Western Ukraine and Western Belorussia on 17 September 1939" Postage stamps from the USSR, 1940.]]

The response of non-ethnic Poles to the situation caused considerable complications. Many [[Ukraine|Ukrainians]], [[Belarus]]ians and [[Jew]]s welcomed the invading troops.<ref name="Gross 32-33" /> Local Communists gathered people to welcome the [[Red Army]] troops in the traditional Slavic way by presenting bread and salt in the eastern suburb of [[Brest, Belarus|Brest]]. A sort of [[triumphal arch]] on two poles, decked with spruce branches and flowers was fashioned for this occasion. A slogan in Russian on a long red banner, glorifying the [[USSR]] and welcoming the Red Army, crowned the arch.<ref>{{cite web |url=http://www.vb.by/article.php?topic=36&article=14200 |script-title=ru:Радость была всеобщая и триумфальная |author=Юрий Рубашевский. |work=[[Vecherniy Brest]] |date=16 September 2011 |language=ru |access-date=15 December 2011 |archive-date=31 December 2013 |archive-url=https://web.archive.org/web/20131231001210/http://www.vb.by/article.php?topic=36&article=14200 |url-status=dead }}</ref> The event was recorded by [[Lev Mekhlis]], who reported to Stalin that the people of the West Ukraine welcomed the Soviet troops "like true liberators".<ref name="Montefiore 312" /> The [[Organization of Ukrainian Nationalists]] rebelled against Polish rule and Communist partisans stirred up local revolts, such as in [[Skidel]].<ref name="Sanford 20-24" />

===International reaction===
{{See also|Western betrayal}}
France and Britain refrained from a critical reaction to the Soviet invasion and annexation of Eastern Poland since neither country expected or wanted a confrontation with the Soviet Union at that time.<ref name="Prazmowska 44-45" /><ref name="Hiden-Lane 148" /> Under the terms of the [[Polish-British Common Defence Pact]] of 25 August 1939, Britain had promised assistance if a European power attacked Poland.{{#tag:ref|The "Agreement of Mutual Assistance between the United Kingdom and Poland" (London, 25 August 1939) states in Article 1: "Should one of the Contracting Parties become engaged in hostilities with a European Power in consequence of aggression by the latter against that Contracting Party, the other Contracting Party will at once give the Contracting Party engaged in hostilities all the support and assistance in its power."<ref name="Stachura 125" />|group="Note"}} A secret protocol of the pact, however, specified that the European power referred to Germany.<ref name="Hiden-Lane 143-144" /> When Polish Ambassador [[Edward Bernard Raczyński|Edward Raczyński]] reminded [[Secretary of State for Foreign and Commonwealth Affairs|Foreign Secretary]] [[Lord Halifax]] of the pact, he was bluntly told that it was Britain's exclusive right to declare war on the Soviet Union or not.<ref name="Prazmowska 44-45" /> [[Prime Minister of the United Kingdom|British Prime Minister]] [[Neville Chamberlain]] considered making a public commitment to restore the Polish state but eventually issued only general condemnations.<ref name="Prazmowska 44-45" /> This stance represented Britain's attempt at balance as its security interests included trade with the USSR that would support its war effort and might lead to a possible future Anglo-Soviet alliance against Germany (which indeed happened two years later).<ref name="Hiden-Lane 143-144" /> Public opinion in Britain was varied among expressions of outrage at the invasion on the one hand and a perception that Soviet claims in the region were reasonable on the other.<ref name="Hiden-Lane 143-144" />

While France had made promises to Poland, including the provision of air support, these were not honoured. A [[Franco-Polish Military Alliance]] was signed in 1921 and amended thereafter. The agreements were not strongly supported by the French military leadership, though and the relationship deteriorated during the 1920s and 1930s.<ref name="Hehn 69-70" /> The French correctly considered the German-Soviet alliance to be fragile and overt denunciation of, or action against the Soviet Union would serve neither France's nor Poland's best interests.<ref name ="Hiden-Lane 148" /> Once the Soviets had occupied Poland, the French and the British realized there was nothing they could do for Poland on short notice and plans for a long-term victory were devised instead. The French forces, that had [[Saar Offensive|advanced tentatively into the Saar region in early September]], retreated behind the [[Maginot Line]] upon the Polish defeat on 4 October.<ref name="Jackson 75" />

On 1 October 1939, [[Winston Churchill]] stated in public: {{blockquote|... That the Russian armies should stand on this line was clearly necessary for the safety of Russia against the Nazi menace. At any rate, the line is there, and an Eastern Front has been created which Nazi Germany does not dare assail. When Herr von Ribbentrop was summoned to Moscow last week it was to learn the fact, and to accept the fact, that the Nazi designs upon the Baltic States and upon the Ukraine must come to a dead stop.<ref name="Churchill2013">{{cite book|author=Winston S. Churchill|title=Into Battle, 1941|url=https://books.google.com/books?id=iVwqAAAAQBAJ&pg=PT96|date=1 April 2013|publisher=Rosetta Books|isbn=978-0-7953-2946-3|page=96}}</ref>}}Since the Molotov-Ribbentrop Pact was not an official alliance,<ref name="Moorhouse20142">{{cite book|author=Roger Moorhouse|url=https://books.google.com/books?id=Xv5sAwAAQBAJ|title=The Devils' Alliance: Hitler's Pact with Stalin, 1939–1941|date=21 August 2014|publisher=Random House|isbn=978-1-4481-0471-0|page=4|quote=It is worth clarifying that the Nazi-Soviet Pact was not an alliance as such, it was a treaty of non-aggression. Consequently, aside from the metaphorical tide used here - The Devils' Alliance - I generally refrain from referring to Hitler and Stalin as 'allies' or their collaboration as an 'alliance'. However, that clarification should not blind us to the fact that the Nazi-Soviet relationship between 1939 and 1941 was a profoundly important one, which consisted of four further agreements after the pact of August 1939 and was, therefore, close to an alliance in many respects. Certainly it was far more vital and far more crucial to both sides than, for instance, Hitler's alliance with Mussolini's Italy. Hitler and Stalin were allies in all but name.}}</ref> modern scholarship has described the German and Soviet cooperation in the invasion of Poland as [[co-belligerence]].<ref name=":0">{{Cite journal|last=Hager|first=Robert P.|date=2017-03-01|title="The laughing third man in a fight": Stalin's use of the wedge strategy|url=https://online.ucpress.edu/cpcs/article-abstract/50/1/15/607/The-laughing-third-man-in-a-fight-Stalin-s-use-of?redirectedFrom=fulltext|journal=Communist and Post-Communist Studies|language=en|volume=50|issue=1|pages=15–27|doi=10.1016/j.postcomstud.2016.11.002|issn=0967-067X|quote=The Soviet Union participated as a cobelligerent with Germany after 17 September 1939, when Soviet forces invaded eastern Poland}}</ref><ref name=":1">{{Cite journal|last=Blobaum|first=Robert|date=1990|title=The Destruction of East-Central Europe, 1939–41|url=https://heinonline.org/HOL/Page?handle=hein.journals/probscmu39&id=686&div=&collection=|journal=Problems of Communism|volume=39|pages=106|quote=As a co-belligerent of Nazi Germany, the Soviet Union secretly assisted the German invasion of central and western Poland before launching its own invasion of eastern Poland on 17 September}}</ref>

==Aftermath==
{{Main|Occupation of Poland (1939–1945)}}
{{further|History of Poland (1939–1945)|Polish prisoners of war in Soviet Union (after 1939)}}
[[File:Jeńcy1.jpg|thumb|right|Polish prisoners of war captured by the Red Army during the Soviet invasion of Poland in 1939|alt=A photo of a crowd of marching Polish prisoners of war captured by the Red Army during the Soviet invasion of Poland]]

In October 1939, Molotov reported to the Supreme Soviet that the Red Army had suffered 737 deaths and 1,862 wounded men during the campaign, a casualty rate that widely contradicted Polish specialist's claims of up to 3,000 deaths and 8,000 to 10,000 wounded.<ref name="Sanford 20-24" /> On the Polish side, 3,000 to 7,000 soldiers died fighting the Red Army as between 230,000 and 450,000 men were taken prisoners.<ref name="Wojsko92" /> The Soviet troops regularly failed to honour commonly accepted terms of surrender. In some cases, after Polish soldiers had been promised to retreat freely Soviet troops arrested them once they had laid down their arms.<ref name="Sanford 20-24" />
[[File:The German-soviet Invasion of Poland, 1939 HU87205.jpg|thumb|[[Red Army]] soldier guarding a Polish [[PWS-26]] trainer aircraft shot down near the city of Równe ([[Rivne]]) in the Soviet occupied part of Poland, 18 September 1939]]
The Soviet Union had ceased to recognise the Polish state upon the start of the invasion. Neither side issued a formal declaration of war. This decision had significant consequences and Rydz-Smigly would be later criticised for it.<ref name="Sanford 22-23, 39" /> The Soviets killed tens of thousands of [[Polish prisoners of war in Soviet Union (after 1939)|Polish prisoners of war]] during the campaign itself.<ref name="Sanford 23" /> On 24 September, the Soviet soldiers killed 42 staff and patients of a Polish military hospital in the village of [[Grabowiec, Zamość County|Grabowiec]], near [[Zamość]].<ref name="Grabowiec" /> Soviet troops also executed all the Polish officers they captured at the [[Battle of Szack]] on 28 September 1939.<ref name="Interia-Szack" /> The [[NKVD]] killed 22,000 Polish military personnel and civilians in the [[Katyn massacre]] in 1940.<ref name="Sanford 20-24" /><ref name="Fischer" /> [[Torture]] was widely used by the NKVD in various prisons, especially in small towns.<ref name="Gross 182" />

[[File:Katyn - decision of massacre p1.jpg|thumb|upright|left|Soviet document, proving the mass execution of Polish officers in the [[Katyn massacre]]|alt=The front page of the Soviet document of decision, with blue hand writing scrawled across the left-center of the page, authorizing the mass execution of all Polish officers who were prisoners of war in the Soviet Union]]

On 28 September 1939, the Soviet Union and Germany signed the [[German–Soviet Treaty of Friendship, Cooperation and Demarcation]], readdressing the secret terms of the [[Molotov–Ribbentrop Pact]]. [[Lithuania]] was incorporated into the Soviet [[sphere of influence]] and the border within Poland was shifted to the east, increasing German territory.<ref name="PWN_KW_old" /> By this arrangement, often described as a fourth [[partition of Poland]],<ref name="Sanford 20-24" /> the Soviet Union secured almost all Polish territory east of the line of the rivers Pisa, Narew, Western Bug and San. This amounted to about {{convert|200000|sqkm|sqmi| abbr=on}} territory, inhabited by 13.5 million Polish citizens.<ref name="Gross 17" /> The border created in this agreement roughly corresponded to the [[Curzon Line]] drawn by the British in 1919, a point that would successfully be utilized by Stalin during negotiations with the [[Allies of World War II|Allies]] at the [[Teheran Conference|Teheran]] and [[Yalta Conference]]s.<ref name="Dallas 557" /> The Red Army had originally sown confusion among the population, claiming that they had come to save Poland from Nazi occupation.<ref name ="Davies96 1001-1003">[[#Reference-Davies96|Davies (1996)]] pp. 1001–1003</ref> Their advance surprised Polish communities and their leaders, who had not been advised on how to respond to a Soviet invasion. Polish and Jewish citizens might initially have preferred Soviet rule to Nazi German rule.<ref name="Gross 24, 32-33" /> However, the Soviet authorities quickly imposed Communist ideology and administration upon their new subjects and suppressed the traditional ways of life. For instance, the Soviet government confiscated, [[nationalized]] and redistributed all private Polish property.<ref name="Piotrowski 11" /> During the two years following the annexation, the Soviet police forces arrested approximately 100,000 Polish citizens.<ref name="Karta" />

The Poles and the Soviets re-established diplomatic relations in 1941, following the [[Sikorski–Mayski Agreement]]. The Soviets broke off talks again in 1943 after the Polish government had demanded an independent examination of the recently discovered Katyn burial pits ([[Katyn massacre]]).<ref name="Soviet note of 1943" /><ref name="Sanford 129" />

Due to denied access to secret Soviet archives, estimates of the number of Polish citizens deported to Siberia and the total number of perished persons under Soviet rule, remained guesswork for decades after the end of the war. Estimates among the numerous publications varied between 350,000 and 1,500,000 for civilians deported to Siberia and between 250,000 and 1,000,000 for the total number of civilians who had died.<ref name="Rieber 14, 32-37" /> With the opening of the Soviet secret archives after 1989, more realistic and potentially smaller numbers were established. In August 2009, on the occasion of the 70th anniversary of the Soviet invasion, the [[Polish Institute of National Remembrance]] announced that research estimates on the number of people deported to Siberia and those who had perished under Soviet wartime rule amounted to around a total of 150,000 Polish citizens.<ref name="Polish experts lower nation's WWII death toll" />

===Belorussia and Ukraine===
{{further|Territories of Poland annexed by the Soviet Union}}
[[File:Polish eagle and Soviet soldier.JPG|thumb|Soviet propaganda depicting the [[Red Army]] as the liberator of [[Ukrainians|Ukrainian]] and [[Belarusians|Belarusian]] peasants from Polish tyranny (the [[Polish eagle]])]]
According to the last official Polish census the 13.5 million inhabitants in [[Polish areas annexed by the Soviet Union|the newly annexed territories]] consisted of 38% Poles (5,1 million), 37% Ukrainians (4,7 million), 14.5% Belarusians, 8.4% Jews, 0.9% Russians and 0.6% Germans.<ref name="Trela-Mazur 294" />

The [[Elections to the People's Assemblies of Western Ukraine and Western Belarus|elections]] of 26 October in the Belorussian and Ukrainian communities were utilized to bestow some degree of legitimacy upon the annexation.{{#tag:ref| The voters were presented with just one candidate for each position of deputy. The Communist party commissars subsequently would press their resolutions in the communities towards complete nationalization of the financial sector and the heavy industries and the transfer of private land to agricultural communities.<ref name="Rieber 29-30" />|group="Note"}} The Belarusians and Ukrainians in Poland had been alienated by the former [[Polonization]] policies of the Polish government and the repression of [[separatist]] movements and thus felt little loyalty towards the Polish cause.<ref name="Stosunki" /><ref name="Davies02 512-513" /> Not all Belarusians and Ukrainians, however, trusted the Soviet regime.<ref name ="Davies96 1001-1003" /> In practice, the poor generally welcomed the Soviets, and the elites tended to join the opposition, despite supporting the reunification itself.<ref name="Stosunki2">{{cite journal |language=pl |first=Marek |last=Wierzbicki |url=http://www.bialorus.pl/index.php?secId=49&docId=60&&Rozdzial=historia |title=Stosunki polsko-białoruskie pod okupacją sowiecką (1939–1941) |journal=Białoruskie Zeszyty Historyczne |publisher=Biełaruski histaryczny zbornik |issue=20 |year=2003 |pages=186–188 |access-date=16 July 2007 |url-status=dead |archive-url=https://web.archive.org/web/20080623073822/http://www.bialorus.pl/index.php?secId=49&docId=60&&Rozdzial=historia |archive-date=23 June 2008 }}</ref><ref name="Nowak" /> The Soviets eventually introduced complete [[Sovietization]] policies in Western Belorussia and Western Ukraine, including compulsory [[collectivization]] throughout the whole region. In the process, all political parties and public associations were ruthlessly destroyed and their leaders imprisoned or executed as "enemies of the people".<ref name ="Davies96 1001-1003" /> The Soviet authorities also suppressed the [[anti-Polish]] [[Organization of Ukrainian Nationalists]] for an independent and undivided Ukrainian state, that had actively resisted the Polish regime since the 1920s.<ref name="Nowak" /><ref name="Miner 41-42" /> The unifications of 1939 nevertheless proved to be decisive events in the history of the [[Ukraine]] and [[Belarus]], as these created the precursors to the two republics, that eventually achieved independence after the [[fall of the Soviet Union]] in 1991.<ref name="Wilson 17" />

==Communist and later censorship==
[[Politburo]] jargon would stylize the invasion a "liberation campaign" from its inception. The term would consequently be utilized throughout Soviet history among official references and publications.<ref name="Rieber 29" /> Despite the 1979 publication of a recovered copy of the secret protocols of the Molotov–Ribbentrop Pact in the Western media, the Soviet Union continued to deny their existence until 1989.<ref>{{cite web|url= https://communistcrimes.org/en/criminal-secret-protocol-molotov-ribbentrop-pact-chronology |title= The Criminal Secret Protocol of the Molotov-Ribbentrop Pact. Chronology – 23 August 1979   |date=22 August 2019  |publisher= Estonian Institute of Historical Memory  |access-date =19 September 2020}}</ref><ref name="Biskupski 147" />
Attempts to record the factual and fully detailed history of the 1939 Soviet invasion and its consequences have only been made after the fall of the USSR. Soviet [[Censorship in the Soviet Union|censorship]] and inaccessible archives prevented serious historic research until 1991.<ref name="Kubik 277" /><ref name="Sanford 214-216" /> Censorship was also applied in the [[People's Republic of Poland]] in order to preserve the image of "Polish-Soviet friendship" which was promoted by the two communist governments. Accounts of the 1939 campaign were to portray the invasion in accord with the Soviet [[Politburo]] narrative – a reunification of the Belarusian and Ukrainian peoples and the liberation of the Polish people from "Oligarchic Capitalism". The authorities strongly discouraged any study in depth and the teaching of the subject.<ref name="Fischer" /><ref name="Orlik-Rückemann 20" /><ref name="Ferro 258" /> Various underground publishers and artists addressed the issue, as in the 1982 [[protest song]] "Ballada wrześniowa{{-"}} by [[Jacek Kaczmarski]].<ref name="Orlik-Rückemann 20" /><ref name="Kaczmarski" />

=== Russia ===
In a 2009 letter to the Polish daily newspaper {{Lang|pl|[[Gazeta Wyborcza]]}}, Russian Prime Minister [[Vladimir Putin]] stated that the [[Molotov–Ribbentrop Pact]] of August 1939 was "immoral".<ref>{{cite book |last=Kuhrt |first=Natasha |date=2014 |title=Russia and the World: The Internal-External Nexus |url=https://books.google.com/books?id=1QLPBAAAQBAJ&pg=PA23 |publisher=Routledge |page=23 |isbn=978-1-317-85037-3}}</ref> In 2015, however, as President of the Russian Federation, he commented: "In this sense I share the opinion of our culture minister ([[Vladimir Medinsky]] praising the pact as a triumph of Stalin's diplomacy) that this pact had significance for ensuring the security of the USSR".<ref name="YahooMay2015">{{cite news |date= 10 May 2015|title=Putin defends notorious Nazi-Soviet pact |url=https://www.yahoo.com/news/putin-defends-notorious-nazi-soviet-pact-174156837.html |newspaper=Yahoo News|access-date=3 September 2016}}</ref>

In 2016, the Russian Supreme Court upheld the sentence of a lower court, that had found blogger Vladimir Luzgin<ref>{{cite web |url=http://news.sky.com/story/how-russia-is-engaged-in-a-battle-for-its-own-history-10691897 |title=How Russia is engaged in a battle for its own history |publisher=Sky News |date=11 December 2016}}</ref> guilty of the "rehabilitation of Nazism" after he had posted a text on social media that characterized the invasion of Poland in 1939 as a joint effort by Nazi Germany and the Soviet Union.<ref>{{cite web |url=http://www.tol.org/client/article/26273-russia-supreme-court-luzgin-1939-ussr-poland-nazi-germany-molotov-ribbentrop.html |title=Russia's Supreme Court Questions USSR's Role in 1939 Invasion of Poland |first=Azarova |last=Anna |date=2 September 2016 |access-date=3 September 2016}}</ref>

On September 17, 2021, Russia's Foreign Ministry marked the 82nd anniversary of the Soviet invasion of Poland with a Twitter post describing it as a "campaign of liberation", stating that "...peoples of Western Belorussia and Western Ukraine greeted the Soviet soldiers with rejoicing".<ref>{{cite web |url=https://twitter.com/MID_RF/status/1438768364353114115 |publisher=Официальный аккаунт МИД России |date=17 September 2021|title=17 сентября 1939 г. Красная Армия начала освободительный поход на территории Польши. Советские войска вышли на линию Керзона, не позволив вермахту подойти к Минску.}}</ref>

==See also==
<!--♦♦♦ Please keep the list in alphabetical order ♦♦♦-->
* [[Cursed soldiers]] 1944–1947
* [[Evacuation of Polish civilians from the USSR in World War II]]
* [[Germany–Soviet Union relations, 1918–1941]]
* [[History of Poland (1939–1945)]]
* [[Polish Operation of the NKVD|Polish Operation of the NKVD 1937–1938]]
* [[Russian involvement in regime change]]
* [[Soviet repressions of Polish citizens (1939–1946)]]
* [[List of German military equipment of World War II]]
* [[List of Soviet Union military equipment of World War II]]
* [[List of World War II military equipment of Poland]]

== Notes ==
{{reflist|group="Note"}}

== References ==
=== Citations ===
{{reflist
|refs =
<ref name="Davies72 xi">[[#Reference-Davies72|Davies (1972)]] p.&nbsp;xi</ref>

<ref name="Kaczmarski">{{cite web |url = http://www.kaczmarski.art.pl/tworczosc/wiersze_alfabetycznie/kaczmarskiego/b/ballada_wrzsniowa.php |title = Ballada wrześniowa |first=Jacek |last=Kaczmarski |language=pl |trans-title = September's tale |access-date = 15 November 2006 |url-status=dead |archive-url = https://archive.today/20121209133244/http://www.kaczmarski.art.pl/tworczosc/wiersze_alfabetycznie/kaczmarskiego/b/ballada_wrzsniowa.php |archive-date = 9 December 2012 }}</ref>

<ref name="Krivosheev">Кривошеев Г. Ф., ''Россия и СССР в войнах XX века: потери вооруженных сил. Статистическое исследование'' (Krivosheev G. F., ''Russia and the USSR in the wars of the 20th century: losses of the Armed Forces. A statistical survey'', Greenhill 1997, {{ISBN|1-85367-280-7}}) See also: {{cite book |first=Grigory Fedot |last=Krivosheev |title=Soviet casualties and combat losses in the twentieth century |location=London |publisher=Greenhill Books |year=1997 |isbn=1-85367-280-7 }} Same.</ref>

<ref name="Miner 41-42">[[#Reference-Miner|Miner]] pp.&nbsp;41-42</ref>

<ref name="Neilson 275">[[#Reference-Neilson|Neilson]] p. 275</ref>

<ref name="SCHULENBURG1">{{cite web |url = http://avalon.law.yale.edu/20th_century/ns069.asp| title=The German Ambassador in the Soviet Union, (Schulenburg) to the German Foreign Office No. 317 |publisher=Lillian Goldman Law Library |access-date=11 June 2009 |work=Avalon project }}</ref>

<ref name="Stanley 29">[[#Reference-Stanley|Stanley]] p. 29</ref>

<ref name="Weinberg 963">[[#Reference-Weinberg|Weinberg]] p. 963</ref>

<ref name="Kushner 219">[[#Reference-Kushner|Kushner]], p.&nbsp;219</ref>

<ref name="Biskupski 147">[[#Reference-Biskupski|Biskupski & Wandycz]] p. 147</ref>

<ref name="Carley 303-341">[[#Reference-Carley|Carley]] 303–341</ref>

<ref name="Dallas 557">[[#Reference-Dallas|Dallas]] p. 557</ref>

<ref name="Davies 22, 504">[[#Reference-Davies02|Davies (2002)]] pp. 22, 504</ref>

<ref name="Davies 371-373">[[#Reference=Davies02|Davies (2002)]] pp. 371–373</ref>

<ref name="Davies 376">[[#Reference-Davies02|Davies (2002)]] p. 376</ref>

<ref name="Davies 504">[[#Reference-Davies02|Davies (2002)]] p. 504</ref>

<ref name="Davies02 512-513">[[#Reference-Davies02|Davies (2002)]] pp 512–513.</ref>

<ref name="Davies72 29">[[#Reference-Davies72|Davies (1972)]] p. 29</ref>

<!-- <ref name="Davies96 440">[[#Reference-Davies96|Davies (1996)]] p. 440</ref> -->

<ref name="Davies96 1001">[[#Reference-Davies96|Davies (1996)]] p. 1001</ref>

<ref name="Degras 37-45">[[#Reference-Degras|Degras]] pp. 37–45</ref>

<ref name="Dunnigan 132">[[#Reference-Dunnigan|Dunnigan]] p. 132</ref>

<ref name="Ferro 258">[[#Reference-Ferro|Ferro]] p. 258</ref>

<ref name="Fischer">{{cite web |first=Benjamin B. |last=Fischer |url=https://www.cia.gov/library/center-for-the-study-of-intelligence/csi-publications/csi-studies/studies/winter99-00/art6.html |archive-url=https://web.archive.org/web/20070613112054/https://www.cia.gov/library/center-for-the-study-of-intelligence/csi-publications/csi-studies/studies/winter99-00/art6.html |url-status=dead |archive-date=13 June 2007 |title=The Katyn Controversy: Stalin's Killing Field |work=Studies in Intelligence |access-date=16 July 2007}}</ref>

<ref name="Grabowiec">{{cite web |language=pl |url=http://www.grabowiec.pl/portal/publikacje/epizod_roztrzelany_szpital.pdf |title=Rozstrzelany Szpital |trans-title=Executed Hospital |publisher=Tygodnik Zamojski |access-date=28 November 2006 |date=15 September 2004 |url-status=dead |archive-url=https://web.archive.org/web/20070307143816/http://www.grabowiec.pl/portal/publikacje/epizod_roztrzelany_szpital.pdf |archive-date=7 March 2007 }}</ref>

<ref name="Gronowicz 51">[[#Reference-Gronowicz|Gronowicz]] p. 51</ref>

<ref name="Gross 3">[[#Reference-Gross|Gross]] p. 3</ref>

<ref name="Gross 17">[[#Reference-Gross|Gross]] p. 17</ref>

<ref name="Gross 17-18">[[#Reference-Gross|Gross]] pp. 17–18</ref>

<ref name="Gross 182">[[#Reference-Gross|Gross]] p. 182</ref>

<ref name="Gross 24, 32-33">[[#Reference-Gross|Gross]] pp. 24, 32–33</ref>

<ref name="Gross 32-33">[[#Reference-Gross|Gross]] pp. 32–33</ref>

<ref name="Hehn 69-70">[[#Reference-Hehn|Hehn]] pp. 69–70</ref>

<ref name="Henderson 16-18">[[#Reference=Henderson|Henderson]] pp. 16–18</ref>

<ref name="Hiden-Lane 143-144">[[#Reference-Hiden-Lane|Hiden & Lane]] pp. 143–144</ref>

<ref name="Hiden-Lane 148">[[#Reference-Hiden-Lane|Hiden & Lane]] p. 148</ref>

<ref name="Interia-Szack">{{cite web |language=pl|url=http://encyklopedia.interia.pl/haslo?hid=106003 |title=Szack |work=Encyklopedia Interia |access-date=28 November 2006}}</ref>

<ref name="Jackson 75">[[#Reference-Jackson|Jackson]] p. 75</ref>

<ref name="Karta">{{cite web| language=pl |url= http://www.indeks.karta.org.pl/represje_sowieckie_4.html |title=Represje 1939–41 Aresztowani na Kresach Wschodnich |trans-title=Repressions 1939–41. Arrested on the Eastern Borderlands. |work=Ośrodek Karta |access-date=15 November 2006 |archive-url = https://web.archive.org/web/20061021190059/http://www.indeks.karta.org.pl/represje_sowieckie_4.html |archive-date = 21 October 2006}}</ref>

<ref name="Kenéz 129-131">[[#Reference-Kenéz|Kenéz]] pp. 129–131</ref>

<ref name="Kitchen 74">[[#Reference-Kitchen|Kitchen]] p. 74</ref>

<ref name="Kubik 277">[[#Reference-Kubik|Kubik]] p. 277</ref>

<ref name="Kutrzeba 524, 528">[[#Reference-Kutrzeba|Kutrzeba]] pp. 524, 528</ref>

<ref name="Leinwald">{{cite web | author=Artur Leinwand | title=Obrona Lwowa we wrześniu 1939 roku | publisher=Instytut Lwowski | year=1991 | url = http://www.lwow.com.pl/rocznik/obrona39.html | access-date=16 July 2007}}</ref>

<ref name="Lukowski">{{cite book |last1= Lukowski |first1= Jerzy |author1-link= Jerzy Lukowski |last2= Zawadzki  |first2= Hubert |year= 2001 |title = A Concise History of Poland |location= Cambridge, England |publisher= [[Cambridge University Press]] |isbn= 0-521-55917-0 | page=204 }}</ref>

<ref name="Manvell-Fraenkel 76">[[#Reference-Manvell-Fraenkel|Manvell-Fraenkel]] p. 76</ref>

<ref name="Montefiore 312">[[#Reference-Montefiore|Montefiore]] p. 312</ref>

<ref name="Mowat 648">[[#Reference-Mowat|Mowat]] p. 648</ref>

<ref name="Mowat 648-650">[[#Reference-Mowat|Mowat]] pp. 648–650</ref>

<ref name="Moynihan 93">[[#Reference-Moynihan|Moynihan]] p. 93</ref>

<ref name="Neilson 298">[[#Reference-Neilson|Neilson]] p. 298</ref>

<ref name="Neilson 311">[[#Reference-Neilson|Neilson]] p. 311</ref>

<ref name="Neilson 315">[[#Reference-Neilson|Neilson]] p. 315</ref>

<ref name="Nowak">[[#Reference-Nowak|Nowak]] (online)</ref>

<ref name="Orlik-Rückemann 20">[[#Reference-Orlik-Rückemann|Orlik-Rückemann]] p. 20</ref>

<ref name="PWN">{{cite web |language=pl |url = http://encyklopedia.pwn.pl/haslo.php?id=3949396 |title=Obozy jenieckie żołnierzy polskich |trans-title=Prison camps for Polish soldiers |work=Encyklopedia PWN |access-date=28 November 2006 }}</ref>

<ref name="PWN_KW_old">[https://web.archive.org/web/20060509003357/http://encyklopedia.pwn.pl/33490_1.html KAMPANIA WRZEŚNIOWA 1939] from [[Internetowa encyklopedia PWN|PWN Encyklopedia]]. Please note that the above link is the [[Internet Archive]] version, mid-2006. The [http://encyklopedia.pwn.pl/haslo.php?id=3959908 new PWN article] {{Webarchive|url=https://web.archive.org/web/20071228231408/http://encyklopedia.pwn.pl/haslo.php?id=3959908# |date=2007-12-28 }} is significantly shorter.</ref>

<ref name="Piotrowski 11">[[#Reference-Piotrowski|Piotrowski]] p. 11</ref>

<ref name="Piotrowski 295">[[#Reference-Piotrowski|Piotrowski]] p. 295</ref>

<ref name="Polish experts lower nation's WWII death toll">{{cite web |title = Polish experts lower nation's WWII death toll |url = http://www.expatica.com/de/news/german-news/Polish-experts-lower-nation_s-WWII-death-toll--_55843.html |access-date=4 November 2009 |date=30 July 2009 |publisher=AFP/Expatica }}</ref>

<ref name="Prazmowska 44-45">[[#Reference-Prazmowska|Prazmowska]] pp. 44–45.</ref>

<ref name="Rieber 14, 32-37">[[#Reference-Rieber|Rieber]] pp. 14, 32–37</ref>

<ref name="Rieber 29">[[#Reference-Rieber|Rieber]] p. 29</ref>

<ref name="Rieber 29-30">[[#Reference-Rieber|Rieber]] pp. 29–30</ref>

<ref name="Rieber 30">[[#Reference-Rieber|Rieber]] p. 30</ref>

<ref name="Roberts 66-73">[[#Reference-Roberts|Roberts]] pp. 66–73</ref>

<ref name="Roberts 74">[[#Reference-Roberts|Roberts]] p. 74</ref>

<ref name="Roshwald 37">[[#Reference-Roshwald|Roshwald]] p. 37</ref>

<ref name="Rummel 130">[[#Reference-Rummel|Rummel]] p. 130</ref>

<ref name="Rummel 132">[[#Reference-Rummel|Rummel]] p. 132</ref>

<ref name="SCHULENBURG2">{{cite web |url=http://avalon.law.yale.edu/20th_century/ns073.asp |title=The German Ambassador in the Soviet Union, (Schulenburg) to the German Foreign Office No. 371|publisher=Lillian Goldman Law Library |access-date=11 June 2009 |work=Avalon project}}</ref>

<ref name="SCHULENBURG3">{{cite web |url=http://avalon.law.yale.edu/20th_century/ns074.asp |title=The German Ambassador in the Soviet Union, (Schulenburg) to the German Foreign Office No. 372 |publisher=Lillian Goldman Law Library |access-date=11 June 2009 |work=Avalon project}}</ref>

<ref name="Sanford 129">[[#Reference-Sanford|Sanford]] p. 129</ref>

<ref name="Sanford 20-24">[[#Reference-Sanford|Sanford]] [https://books.google.com/books?id=tV2AAgAAQBAJ&q=3000%2B7000 pp. 20–24]</ref>

<ref name="Sanford 21">[[#Reference-Sanford|Sanford]] p. 21</ref>

<ref name="Sanford 214-216">[[#Reference-Sanford|Sanford]] pp. 214–216</ref>

<ref name="Sanford 22-23, 39">[[#Reference-Sanford|Sanford]] pp. 22–23, 39</ref>

<ref name="Sanford 23">[[#Reference-Sanford|Sanford]] p. 23</ref>

<ref name="Shaw 119">[[#Reference-Shaw|Shaw]] p. 119</ref>

<ref name="Shirer 503">[[#Reference=Shirer|Shirer]] p. 503</ref>

<ref name="Shirer 525">[[#Reference=Shirer|Shirer]] p. 525</ref>

<ref name="Shirer 536">[[#Reference=Shirer|Shirer]] p. 536</ref>

<ref name="Shirer 537">[[#Reference-Shirer|Shirer]] p. 537</ref>

<ref name="Shirer 541">[[#Reference-Shirer|Shirer]] pp. 541–2</ref>

<ref name="Snyder 77">[[#Reference-Snyder|Snyder]] p. 77</ref>

<ref name="Soviet note of 1943">{{cite web | date=25 April 1943 |title=Soviet Note of April 25, 1943 |url=http://www.electronicmuseum.ca/Poland-WW2/katyn_memorial_wall/kmw_note.html |access-date=19 December 2005 |archive-url = https://web.archive.org/web/20050909042329/http://www.electronicmuseum.ca/Poland-WW2/katyn_memorial_wall/kmw_note.html |archive-date = 9 September 2005}}</ref>

<ref name="Stachura 125">[[#Reference-Stachura|Stachura]] p. 125</ref>

<ref name="Taylor 38">[[#Reference-Taylor|Taylor]] p. 38</ref>

<ref name="Trela-Mazur 294">[[#Reference-Trela-Mazur|Trela-Mazur]] p. 294</ref>

<ref name="Tucker 612">[[#Reference-Tucker|Tucker]] p. 612</ref>

<ref name="WIF">{{cite book |title=Operatsiia Groza, Ili, Oshibka V Tretem Znake: Istoricheskaia Khronika|last=Bunich |first=Igor |year=1994 |publisher=VITA-OBLIK |isbn=5-85976-003-5 |page=88 }}</ref>

<ref name="Watson 695">[[#Reference=Watson|Watson]] p. 695</ref>

<ref name="Watson 695-722">[[#Reference-Watson|Watson]] p. 695–722</ref>

<ref name="Watson 698">[[#Reference=Watson|Watson]] p. 698</ref>

<ref name="Watson 708">[[#Reference=Watson|Watson]] p. 708</ref>

<ref name="Watson 713">[[#Reference-Watson|Watson]] p. 713</ref>

<ref name="Weinberg 55">[[#Reference-Weinberg|Weinberg]] p. 55</ref>

<ref name="Wettig 47">[[#Reference-Wettig|Wettig]] p. 47</ref>

<ref name="Wilson 17">[[#Reference-Wilson|Wilson]] p. 17</ref>

<ref name="Wojsko90">[[#Reference-Topolewski-Polak|Topolewski & Polak]] p. 90</ref>

<ref name="Wojsko92">[[#Reference-Topolewski-Polak|Topolewski & Polak]] p. 92</ref>

<ref name="Zaloga 80">[[#Reference-Zaloga|Zaloga]] p. 80</ref>

<ref name="pledge">{{cite web |title=Telegram: His Majesty's Ambassador in Berlin – Dept of State 8/25/39 |url=http://www.fdrlibrary.marist.edu/psf/box31/t295s04.html |archive-url=https://web.archive.org/web/20020220043844/http://www.fdrlibrary.marist.edu/psf/box31/t295s04.html |url-status=dead |archive-date=20 February 2002 |publisher=Franklin D. Roosevelt Presidential Library and Museum |access-date=11 June 2009}}</ref>

<!-- Unused citations
<ref name="Levin 31-32">[[#Reference-Levin|Levin]] pp. 31–32</ref>

<ref name="Mendelsohn 218">[[#Reference-Mendelsohn|Mendelsohn]] p. 218</ref>
-->
}}

=== Sources ===
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{{refend}}

==External links==
*{{Commons category-inline}}
*[https://en.wikisource.org/wiki/Molotov%E2%80%93Ribbentrop_Pact Molotov–Ribbentrop Pact]

{{Polish wars and conflicts}}
{{Russian Conflicts}}
{{Soviet zones of occupation}}
{{Joseph Stalin}}
{{Nazi-Soviet relations}}

[[Category:Soviet invasion of Poland| ]]
[[Category:1939 in the Soviet Union]]
[[Category:Conflicts in 1939]]
[[Category:September 1939 events]]
[[Category:October 1939 events]]
[[Category:Military operations involving the Soviet Union|Poland]]
[[Category:Polish–Russian wars]]
[[Category:Invasion of Poland]]
[[Category:Soviet military occupations]]
[[Category:Stalinism in Poland]]
[[Category:Belarus in World War II]]
[[Category:Western Belorussia (1918–1939)]]