Definition of epic proportions:
Such that someone is willing to compose an epic.
An unsung hero is one who failed to properly inspire the poets - poets find heroic deeds and generosity to poets far more inspirational than heroic deeds alone.
Like the current situation where a small event with good video is more newsworthy than a large one without, I suspect the Trojan War was an epic event in large part because of the quality of the poets who sang of it. It did involve the destruction of a significant enough city that evidence could be found thousands of years later, so we aren't talking about a completely media-generated event.
