Northeast of Poland, Polish forces (the Polish 1st Legions Infantry Division reinforced by the units of the Wyszków Operational Group) under Gen. Wincenty Kowalski stop retreating and launch a major counter-attack for the town of Kałuszyn near Mińsk Mazowiecki. The town is recaptured after an incredibly brave and heroic charge by 85 infantry of the 4th squadron of the Polish 11th Uhlans Regiment. These men (33 perish) having cleared a path, the rest of the Polish infantry follows them. This is known as the Battle of Kałuszyn and is considered a high point for Polish forces in the war.

German forces (4th Light Division) that have taken Jaroslaw now approach the fortress of Przemyśl, crossing the River San. The Germans attempt to take it on the run but are repelled. The Poles counterattack during the evening, but run into German machine guns and withdraw into the fortress.

The battle on the Bzura River continues.

The Germans capture 60,000 Polish troops at Radom. This completes the capture of the key industrial region of Upper Silesia.

In Warsaw, German troops are blocked and remain on the outskirts.

Battle of the Atlantic: Germany, in response to the British announcement of a blockade of Germany, announce their own blockade of Great Britain. German radio says that they must "reply to [the British blockade] with the same methods."

The Polish government orders its submarines to either break out to Great Britain or be interned in Sweden.

Western Front: French forces advance in the Saar, including a bayonet charge near Merzig.

German Intelligence: The Germans successfully crack a key British cipher used by merchant ships, enabling them to identify convoy meeting points.

German attempts to jam Radio Warsaw fail, permitting further broadcasts from the besieged capital.

British Government: The Ministry of Information issues a declaration of policy that no peace is possible with a government led by Adolf Hitler because he cannot be trusted.

The King gifts a new fund of the British Red Cross and Order of St. John with £5,000.

Saudi Arabia: The country breaks off diplomatic relations with Germany despite having concluded an arms agreement with the Germans recently. They remain formally neutral.

Anglo-American diplomacy: President Roosevelt sends a brief message to First Lord of the Admiralty Winston Churchill asking him to "keep me in touch personally with anything you want me to know about." Churchill replies immediately, commencing his famous wartime correspondence with FDR. He signs his message "Naval Person."

Benito Mussolini on the cover of Life Magazine, September 11, 1939.

September 1939

September 1, 1939: Invasion of Poland
September 2, 1939: Danzig Annexed
September 3, 1939: France, Great Britain Declare War
September 4, 1939: First RAF Raid
September 5, 1939: The US Stays Out
September 6, 1939: Battle of Barking Creek
September 7, 1939: Polish HQ Bugs Out
September 8, 1939: War Crimes in Poland
September 9, 1939: The Empire Strikes Back
September 10, 1939: The Germans Break Out
September 11, 1939: Battle of Kałuszyn
September 12, 1939: The French Chicken Out
September 13, 1939: The Battle of Modlin
September 14, 1939: Germany Captures Gdynia
September 15, 1939: Warsaw Surrounded
September 16, 1939: Battle of Jaworów
September 17, 1939: Soviets Invade Poland
September 18, 1939: Lublin Falls
September 19, 1939: Germans, Soviets Hook Up
September 20, 1939: the Kraków Army Surrenders
September 21, 1939: Romania Convulses
September 22, 1939: Joint Soviet-German Military Parade
September 23, 1939: The Panama Conference
September 24, 1939: The Luftwaffe Bombs Warsaw
September 25, 1939: Black Monday for Warsaw
September 26, 1939: Warsaw on the Ropes
September 27, 1939: Hitler Decides to Invade France
September 28, 1939: Warsaw Capitulates
September 29, 1939: Modlin Fortress Falls
September 30, 1939: Graf Spee on the Loose

2019