What an interesting question! It begs the debate over the value of history and elicits a philosophical commentary on whether or not truth is an absolute good, a relative good, or perhaps has no merit whatsoever.
Taking the latter issue first, a skeptic might easily dispense with the notion that truth is an absolute good. For example, telling an adoring parent that they have an ugly child may be the truth, but it is a truth that serves no purpose save to do harm. Hence, truth cannot be an absolute defense for any action.
On the other end of the spectrum, one cannot completely dispense with the value of truth either. Telling a child not to put his or her hand on the hot stove because it will cause injury has value, and in its own small way is a noble act, as it safeguards the interests of another.
Accordingly, it would seem that truth has virtue under some circumstances, and not others--and so is a relative value.
What then is the relative value of a drop of truth in an ocean of lies? Perhaps the most facile argument is that it provides contrast. Were there no such thing as truth, how would you begin to define what a lie is? A lie, quite simply, is the absence of truth.
Few are naive enough to believe that a solitary truth will offset an avalanche of falsehood, and history is replete with such avalanches. Typically, right or wrong, winners of conflicts write the history. Still, somehow, civilization seems to advance in fits and starts. Human wrongs become more widespread. The rule of law becomes more and more accepted. Law itself becoming tool of control. The standard of living changes, admittedly unevenly, but globally nonetheless.
One must ask themselves, are those advances based upon the perpetuation of a culture of lies, or on the emergence of truth. And, in a seeming contradiction to the above, maybe there are even absolute truths. That there are such things as human dignity, right and wrong, freedom of action, and so on, irrespective of what we say or do, and what lies we tell one another.