All about Invasion of Poland – (05)…
Phase 2: Soviet invasion…
From the beginning, the German government repeatedly asked Vyacheslav Molotov whether the Soviet Union would keep to its side of the partition bargain. Soviet forces attacked Poland on 17 September. It was agreed that the USSR would relinquish its interest in the territories between the new border and Warsaw in exchange for inclusion of Lithuania in the Soviet „zone of interest”.
By 17 September 1939, the Polish defence was already broken and the only hope was to retreat and reorganize along the Romanian Bridgehead. However, these plans were rendered obsolete nearly overnight, when the over 800,000 strong Soviet Red Army entered and created the Belarussian and Ukrainian fronts after invading the eastern regions of Poland in violation of the Riga Peace Treaty, the Soviet-Polish Non-Aggression Pact, and other international treaties, both bilateral and multilateral. Soviet diplomacy claimed that they were „protecting the Ukrainian and Belarusian minorities of eastern Poland since the Polish government had abandoned the country and the Polish state ceased to exist”.
Polish border defence forces in the east, known as the Korpus Ochrony Pogranicza, consisted of about 25 battalions. Edward Rydz-Śmigły ordered them to fall back and not engage the Soviets. This, however, did not prevent some clashes and small battles, such as the Battle of Grodno, as soldiers and local population attempted to defend the city. The Soviets murdered numerous Polish officers, including prisoners of war like General Józef Olszyna-Wilczyński. The Organization of Ukrainian Nationalists rose against the Poles, and communist partisans organized local revolts, robbing and murdering Poles. Those movements were quickly disciplined by the NKVD. The Soviet invasion was one of the decisive factors that convinced the Polish government that the war in Poland was lost. Prior to the Soviet attack from the east, the Polish military’s fall-back plan had called for long-term defence against Germany in the south-eastern part of Poland, while awaiting relief from a Western Allies attack on Germany’s western border. However, the Polish government refused to surrender or negotiate a peace with Germany. Instead, it ordered all units to evacuate Poland and reorganize in France.
Meanwhile, Polish forces tried to move towards the Romanian Bridgehead area, still actively resisting the German invasion. From 17 September to 20 September Polish armies Kraków and Lublin were crippled at the Battle of Tomaszów Lubelski, the second largest battle of the campaign. The city of Lwów capitulated on 22 September because of Soviet intervention; the city had been attacked by the Germans over a week earlier, and in the middle of the siege, the German troops handed operations over to their Soviet allies. Despite a series of intensifying German attacks, Warsaw—defended by quickly reorganized retreating units, civilian volunteers and militia—held out until 28 September. TheModlin Fortress north of Warsaw capitulated on 29 September after an intense 16-day battle. Some isolated Polish garrisons managed to hold their positions long after being surrounded by German forces. Westerplatte enclave’s tiny garrison capitulated on 7 September and the Oksywiegarrison held until 19 September; Hel Fortified Area was defended until 2 October. In the last week of September, Hitler made a speech in the city of Danzig in which he said:
Poland never will rise again in the form of the Versailles treaty. That is guaranteed not only by Germany, but also… Russia.
Despite a Polish victory at the Battle of Szack, after which the Soviets executed all the officers and NCOs they had captured, the Red Army reached the line of rivers Narew, Western Bug, Vistula and San by 28 September in many cases meeting German units advancing from the other direction. Polish defenders on the Hel peninsula on the shore of the Baltic Sea held out until 2 October. The last operational unit of the Polish Army, General Franciszek Kleeberg’s Samodzielna Grupa Operacyjna „Polesie”, surrendered after the four-day Battle of Kock near Lublin on 6 October marking the end of the September Campaign.
The Polish September Campaign was an instance of total war. Consequently, civilian casualties were high during and after combat. From the start, the Luftwaffe attacked civilian targets and columns of refugees along the roads to wreak havoc, disrupt communications, and target Polish morale. Apart from the victims of the battles, it is alleged that the German forces (both SS and the regular Wehrmacht) murdered several thousand Polish civilians. Also, during Operation Tannenberg, nearly 20,000 Poles were shot at 760 mass execution sites by theEinsatzgruppen.
Altogether, the civilian losses of Polish population amounted to about 150,000–200,000 while German civilian losses amounted to roughly 3,250 (including 2,000 who died fighting Polish troops as members of a fifth column).