Question

I understand that the assassination is what sparked world war I, but what was it that sparked world war II?

Answer 1

the invasion of poland by nazi germany

Answer 2

But this is a little tricky
The japanese invasion of Manchuria sparked it in the pacific-ish region. In mainland europe, germany had begun passively invading nearby areas. After the invasion of Poland by Nazi Germany, Hitler and Stalin partitioned Poland and each took a half, thus the only safe way to say how it was started is to say that:
Naxzi Germany's invasion of Poland sparked World War II
Sorry for the rabble

Answer 3

thank you so much!