So, the History began on that day and there had not been bombings (conventional, though it may be) of cities and villages in Europe. All sides did it. Half of Europe was in ruins. It is a veeeeeeeery weird comment.
No, the Bombs were the last events of the war that cemented the acceptance of civilians as legitimate targets in armed conflict. Yes, all sides treated civilians as legitimate targets (I say exactly that in post 27).