The USSR
Nonaggression pact
soviet union
Germany and Russia
The Soviet Union
Poland was divided by Germany and Russia
Poland
The Hitler/Stalin nonaggression pact was at the expense of Poland. Germany occupied western Poland and the USSR occupied eastern Poland, triggering WW II because Britain and France had promised to defend Poland.
The 1939 invasion of Poland caused Britain to declare war on Germany, which started WWII.
Germany .
the event was when Germany invaded Poland. when Britain and France found out they declare war on Germany.
first answer: nazis second more correct answer: Nazi Germany began the invasion of Poland on 1 Sept. 1939, however the Soviet Union joined Germany in the invasion on 17 Sept. 1939. A conquered Poland was divided between the two invaders. Then at the end of the war, when Germany was defeated, Poland (an ally) was not freed by the Soviets, instead it was occupied & turned into a puppet of the Soviets.
Germany's invasion of Poland.