Education · basic · 12 min
Why did the war start in September 1939?
From the pact of 23 August to the partition of Poland: follow the chain of decisions on the map, then check what you remember.
Step 1 / 5
23 August 1939
Germany and the USSR sign a non-aggression pact. The secret protocol divides Poland and the Baltic region — turn on the 'Alliances' layer to see the new line between Berlin and Moscow.
Event: Molotov–Ribbentrop Pact
The map opens in a new tab — this lesson stays here.