Answer:
how and when but why it happened
That is correct. Were you trying to get someone to confirm that the statement is true?
It utterly exhausted Germany's eastern army and saw to a huge fall in German military moral due to the resounding defeat they suffered. It also weakend the western german army because Hitler pulled men and resources from them to try to win the East from the USSR.
I think it either could be compass rose or legend
It all depends on your personal beliefs now and days. some people believe it started from a bang, others believe that God from the bible created everything, and others believe that there are multiple gods that created the universe and everything. I say you do some research and figure out which of the hundreds of tales you believe.
hope this helps