Unfinished business from the end of WWI.
Germany invaded Poland
Hitler invaded Poland before World War 2 started and it was the reason many countries declared war against Germany.
Germany started world war 2 when they invaded poland
In world war 1,germany started the war,but in world war 2,japan started it and usa ended the war
world war 1 started July 28th 1914 and world war 2 started 3rd September 1939
The German Invasion of Poland started World War 2.
The most simple reason of all: Good VS. Evil.
The bombing of Pearl Harbor was the main thing that started the war
Adolf Hitler started world war two when crowned chancellor of germany and invaded country
Nazism started World War 2
World War 2 was started in 1939
It started on 1st of September 1939.