Almost every country/nation/state, in whatever form, has started something resembling agression against another, in some cases winning, at other times being the loser and facing the winner's justice.
It's a question of time: how far back do you want to go? The British, Americans, French, Italians, Russians to name but a few have all had their asses kicked after starting wars. Nobody likes losing so it's great to tell other people how bad and inhuman they are when they lose. It's natural that no-one wants to remember their own faults and move the focus swiftly to something else. It makes people feel better about themselves even if there really is nothing to feel better about because we are all human and have the same weaknesses.