| 1 Sep | Germany invades Poland. |
| 2 Sep | The passenger liner SS Athenia is sunk by the german submarine U-30. |
| 2 Sep | Italy proclaims neutrality in the german-polish conflict. |
| 3 Sep | Britain, Frace, Australia, New Zealand, India and South Africa declare war on Germany. |
| 5 Sep | United States proclaims neutrality. |
| 7 Sep | French troops enter Saar, Germany. |
| 10 Sep | Canada declares war on Germany. |
| 16 Sep | British carrier HMS Courageous sunk. |
| 17 Sep | Soviet Union invades Poland. |
| 19 Sep | Soviet and german troops meet at Brest-Litovsk, Poland. |
| 27 Sep | Warsaw surrenders. |
| 6 Oct | Last organised resistance in Poland is crushed. |
| 14 Oct | British battleship HMS Royal Oak sunk in the Scapa Flow navalbase by a german submarine. |
| 8 Nov | Failed assassination attempt on Adolf Hitler in Bürgerbräukeller, Munich. The carpenter George Elser is later arrested. |
| 30 Nov | Soviet Union invades Finland. |
| 1 Dec |
Stalin forms a soviet puppet-regime in occupied Terijoki, Finland, led by Otto-Wille Kuusinen. |
| 2 Dec | Soviet Union forces occupies Petsamo, Finland. |
| 17 Dec | German battleship Graf Spee scuttled of Montevideo, Uruguary, following the Battle of the River Plate. |