It could be argued that in a post-literate society where fewer books are read and more movies are made, filmmakers bear an increasing responsibility to be true chroniclers of history, because that is where most people will get their history...

  The trouble with historical fiction, in this case, film, is that it has a much wider reach, which is both a blessing and a curse.  It's a curse in the sense that a movie like "Gladiator" influences the general historical conscience in a way no professional historian can.  If/when fictional works are rife with historical errors, these may stick in the historical conscience of its audience.  There's no problem with an anachronistic piece of costume here and there, but a Roman Emperor stating, for instance, that he wants Rome to return to a Republic is a serious problem...

  What happens to real events when they become the subject of Hollywood feature films?  Is history served?  Is the audience..?

I think that today's filmmakers are far more interested in selling tickets than they are about accurately portraying history.  I agree with you that more and more people are depending on movies for their historical information, and it scares the crap out of me!  Of course there are going to be some exceptions - I think films like Schindler's List, Glory and Saving Private Ryan should be seen by everyone even if they aren't 100% accurate.  The feelings that those movies generated in me were far more powerful than any history lesson.  But where do you draw the line?  Should filmmakers be held to a higher standard when it comes to accuracy, or would it hamper their artistic vision?

Hollywood rarely cares about "reality".  All they care about most of the time is making a movie the way they want it, and by making money.

Of course, then you have those that "have a message to tell".  And they will frequently distort reality, and substitute their own.  And more oftne then not, people will then believe that reality.

But nothing will ever change that.  I worked as a "Military Advisor" for a while, and discovered that Directors really do not want "reality".  That is why we still have the hero shot 10 times, always a "flesh wound", and running through barrages of artillary fire, with no damage from shrapnel at all.

And do not even get me started on LAW rockets destroying tanks, and the other even more silly things I have seen in movies.