Is history... history?

The old adage always says "the victor writes the history".  I am coming to question the universality of this statement.  It seems to me sometimes the historical account pushed into record recounts in great details all the atrocities committed by the victor, while simultaneously washing the vanquished in guiltless attire:  Their atrocities never to be remembered in common society, especially not in polite society.  Any public evidence of such destroyed or removed to the fullest extent possible, and where impossible to erase:  Ignored, defaced, and buried.

... And because now some are trying to ascribe some devilish horrible vision of myself, I assure you I speak not of any specific person or people.  The concept stands for itself.  Very few societies are guilt-free.  I just find it interesting that as time goes by I find more historic reminders that no conflict is one-sided, more often than not, both sides were wrong, and most astonishingly there are those who many, many lifetimes later, will vilify the victor and sanctify the loser, burying all evidence and historical account to the contrary.

This begs the question.  How much of history has been manipulated to the ends of someone whose sole desire is to see the downfall of the victor, and is it possible this has happened often enough that the more distant the memory, the greater the odds that the recounting is in fact itself complete fabrication?