1 September firing her guns during the
battle of Westerplatte; taken by a
Nazi collaborator photographer with the
Associated Press demolish a Polish border crossing after
German bombing during the
battle of Tuchola Forest • Around 04:30 German
Stukas III./
KG1 dive bombers attack Polish
sapper positions around the
Tczew Road Bridge in the unsuccessful attempt to preempt the demolition of the bridge. This is widely recognized as the first attack of the invasion of Poland and subsequently World War II. • At 05:00, approximately 50,000 Slovak soldiers cross the Polish border, beginning the
Slovak invasion of Poland. • At 05:00, the
German Tenth Army,
31st Infantry Division,
1st and
4th Panzer Divisions crossed the Polish border and engaged the Polish
Volhynian Cavalry Brigade and
7th Infantry Division near the village of
Mokra. The
subsequent battle of Mokra led to one of the few Polish victories during World War II, as confusion among the German lines led to the Germans firing on their own positions. • The
German 3rd Army began
attacking the town of
Mława, which was defended by the
Polish 20th Infantry Division. This attack began the German offensive known as the
Battle of the Border. • The
German 4th Army advanced into the
Polish Corridor, but was stopped by a Polish counterattack near
Krojanty. The counterattack, known as the
charge at Krojanty, was by the
18th Uhlans and gave birth to the myth of Polish cavalry attacking German tanks. The battle at Krojanty was one of the several engagements during the
Battle of Tuchola Forest, where German forces were attempting to connect mainland Germany with
East Prussia through the
Tuchola Forest. • The
German 7th Infantry Division, under the command of Major General
Eugen Ott,
attacked fortified Polish defenses near
Węgierska Górka. During the battle, the Germans outnumbers the Polish defenders 100 to 1, but suffered "heavy casualties" after breakthrough attempts were repelled. • The
German 5th Panzer Division began
attacking the
Polish 6th Infantry Division near
Pszczyna amid the Battle of the Border. • The German military
launches an assault on the Polish
Hel Fortified Area, which would last until 2 October. • The
Einsatzgruppen, the
death squads branch of the SS, begin
Operation Tannenberg in Poland, which would kill around 20,000 selected Poles in two months. • The
Free City of Danzig is
annexed by Germany. • The
House of Commons of the United Kingdom passes an emergency military
budget, preparing for war against Germany. •
Polish Navy warships were attacked by German
Luftwaffe aircraft in
Gdańsk Bay (then
Danzig Bay). The subsequent
battle of Danzig Bay was the first naval-air battle of
World War II. • The
German 4th Army crosses the
Brda River. • German troops conduct massacres in
Bukownica,
Gostyń,
Łaziska Dolne,
Łaziska Średnie,
Torzeniec,
Wyszanów,
Parzymiechy and
Zimnowoda, killing over 200 Poles, including women and children. • Bombing of
Skierniewice by the
Luftwaffe begins. • German troops perpetrated massacres in
Albertów,
Imielin,
Jankowice,
Kobielice,
Krzepice,
Lędziny,
Mysłów,
Nierada,
Pińczyce,
Święta Anna,
Zawiść,
Zgoń and
Zrębice, killing 320 Poles, including women and children. • Soviet
Defense Commissar Voroshilov orders seven military districts in the western Soviet Union to increase their combat readiness.
4 September •
Schleswig-Holstein intensifies its bombardment (supported through
21cm howitzers brought from East Prussia) against Polish defenders at Westerplatte as the Battle of Westerplatte continues. • German 8th Army captures five bridges across the
Warta river intact and begins its river crossing. • Polish high command assigns the
41st Infantry Division and
44th Infantry Division, both still in deployment and unready for combat, to frontline duty to throw them into action. • German troops carried out massacres in
Cielętniki,
Częstochowa,
Kruszyna,
Pasternik,
Pławno,
Pszczyna,
Siewierz, and
Sosnowiec, killing over 350 Poles, including women and children. • Start of the evacuation of the Polish
gold reserve from
Warsaw to
Lublin. • The
Luftwaffe bombed a train with civilian refugees from
Ciechanów in
Łukowo.
5 September firing at
Westerplatte, 5 September 1939 •
Edward Rydz-Śmigły orders a general withdrawal by
Army Prusy,
Army Kraków,
Army Poznań and
Army Łódź to the east bank of the
Vistula and behind the
Dunajec. • Rydz-Śmigły orders a counterattack by Wyszków Operational Group with
1st Legions Infantry Division and
33rd Infantry Division at 18:15, though his order does not reach the Operational Group's commander Kowalski until 06:00 the next day. •
Krakow is captured by German forces. • The Polish air force attempts a general offensive and musters 164 sorties with 13 victories and nine planes lost. In the evening, orders are given to move all remaining Polish fighters to Lublin, where 88 fighters are subsequently formed into the newly improvised
Pursuit Brigade. • Decision of the German Ministry of the Interior to dissolve the
Union of Poles in Germany and close Polish minority schools, printing houses, and financial and cooperative institutions.
8 September • German forces reach the outskirts of Warsaw;
9 September on 9 September 1939 • 4th Panzer Division repeats its attack against Warsaw; Panzer Regiment 35 suffers heavy casualties, leading to the eventual recall of 4th Panzer Division from the Warsaw sector. • The German
5th Panzer Division attacked Polish forces at
Pacanów and
Stopnica.
10 September • German 14th Army forces its way across the river San on both sides of
Przemyśl. The gros of the 11th Polish Infantry Division is trapped inside Przemyśl. • German troops capture Skierniewice and
Kostrzyn. • German troops perpetrated massacres in
Bądków,
Gniazdowo, Kłecko,
Laski Szlacheckie,
Piaseczno,
Rawa Mazowiecka,
Stare Rogowo and
Zdziechowa, killing around 190 Poles, including 21 POWs.
11 September • Poland's submarines are ordered via radio to attempt the breakout to British waters, or to otherwise seek internment in neutral ports. • II Corps approaches
Modlin Fortress, where parts of the corps settle in to besiege the defenders, while the main body of the corps advances towards
Dębe. • Germans capture
Sandomierz. • German troops carried out massacres in Bartoszewice,
Koźmice Wielkie,
Kraków,
Łagiewniki,
Parma,
Sadówka,
Stare Kozłowice and
Szczucin, killing some 150 Poles, including over 40 POWs, and 42 Jews.
13 September • The German Group Kaupisch enters Gdynia (Polish remnant resistance in the city continues until 19 September). • The majority of Poland's gold reserve stored by the Polish government in
Śniatyn on the border with
Romania. • Poland's gold reserve evacuated from
Śniatyn to Romania. • Krakow Army attempts a breakout towards the Romanian frontier through Tomaszow Lubelski. • White Eagle Organization (
Organizacja Orła Białego)
Polish resistance organization founded on 20–22 September in
Kraków.
21 September • Polish garrison of Lviv unexpectedly attempts surrender to the withdrawing Germans; • Reinhard Heydrich issues a directive to begin the concentration of Poland's Jews in the major cities to prepare the formation of ghettos and to ease subsequent deportations to concentration camps. • Germans carried out the first mass execution of 88 patients of the
Kocborowo psychiatric hospital at the
Forest of Szpęgawsk.
23 September • Soviets carried out a massacre of 25 Polish POWs in
Husynne. Polish general
Tadeusz Kutrzeba meets with Johannes Blaskowitz to discuss the terms of surrender. • Germans carried out the second mass execution, this time of 16 patients of the Kocborowo psychiatric hospital, at the Forest of Szpęgawsk. • Soviets carried out a massacre of 18 Polish POWs from the
Riverine Flotilla of the Polish Navy in
Mokrany. == October ==