The Soviet Union under Stalin
The Soviet Union under Stalin (28 October 1939)
Historical Map of Russia & the former Soviet Union
On 23 August 1939, even while it was fighting Japan on the Mongolian border, the Soviet Union shocked the world by agreeing to the Molotov–Ribbentrop Pact with Nazi Germany. Formally, this was a non-aggression pact between two ideological enemies. However a secret clause agreed to the division of eastern Europe. When the Germans invaded Poland in September, the Soviets joined in and invaded from the east.
Molotov-Ribbentrop Pact signed
Germany invasion of Poland
Using several German-staged incidents as casus belli, Nazi Germany strikes Wieluń, Poland, with the Luftwaffe at 04:40 on 1 September 1939 - the first blow of World War II. Five minutes later, the German battleship Schleswig-Holstein opens fire on a Polish military transit depot in the Free City of Danzig, with Germany launching an all out attack on Poland's northern, western, and southern borders later that day.