1:World War II begins with the invasion of Poland by Nazi Germany. The resulting invasion of Poland lasts until October 6, 1939, when the final significant Polish military forces surrender at Kock. German operations are conducted under the operational plan Fall Weiss, while in Poland the campaign is referred to as the Polish Defense War of 1939.
7: The siege of Westerplatte concludes with the surrender of its remaining garrison. Polish supreme command relocates to Brześć from Warsaw. Defenses along the Narew begin withdrawal to the Bug River. Tarnów falls to the 14th Army.
8: The Siege of Warsaw begins the land phase with the arrival of German units in the suburbs. The air bombardment had begun at the start of the Campaign. The pocket at Radom is reduced by the 14th Army.
9: The Battle of Bzura begins with a counter-attack against the German 8th Army.
13: The Vistula defenses are penetrated as German forces cross the river south of Warsaw.
14: Germany captures Gdynia and Brest-Litovsk. Siedlce is captured by the 3rd Army.
15: The heaviest fighting of the Battle of Bzura concludes with the Germans having gained the advantage. In the east, Przemyśl is captured by the 14th Army.
17: The eastern front of the Campaign opens with the invasion of Poland by the Soviet Union. Kutno falls to the German 8th Army and Brest-Litovsk (Brześć) falls to the 3rd Army.
6: The Battle of Kock ends with the surrender of defending Polish forces. This is the final significant military resistance to the German or Soviet invasions.