The movies never get it right. History, that is. Now, as a historian (technically, anyway) I could turn this into a rant about that, and I have a book on my shelf that is, essentially, just that: a collection of articles that examine what movies get wrong when they turn to history. As interesting as the book is, though, I think it misses the point. The movies aren't about teaching, they're about storytelling. And while a good history film - or book - has a strong narrative, there's a difference between those and what a movie - or a novel - is trying to do.
In fact, one of the best historical novels I ever read was "The Killer Angels" which was pretty accurate, and made into a pretty accurate movie. But I wouldn't recommend using either to study for a test on the Battle of Gettysburg. By the same token, I love the movie "Glory," which the book on my shelf ripped to shreds. Admittedly, it is inaccurate. Highly so. (Watermelons, in Massachusetts? At that time of year?)
On the other hand, citing it's inaccuracies misses the point. It's not like Hollywood was going to green light multiple movies about African-American Civil War regiments. So while, yes, it's true the 54th was educated Blacks and not slaves, by making the movie 54th a more diverse mix I think it conveyed a broader message. And anyone who missed the symbolism of the watermelons wasn't paying attention.
Hollywood gets a lot of things wrong. Ask any cop, forensic scientist, or plain old physicist. There comes a certain point where certain sacrifices get made for the purpose of a good narrative. There's a line there, mind you, as do too much and you venture over into the realm of the truly silly. Also, sometimes, as a historian I do think that Hollywood could have and should have gone with the truth, and it would have made for just as good cinema. (It's Stirling Bridge, Mr Gibson, Stirling Bridge. Which brings me to...)
With a few examples, Hollywood gets most of it wrong. Braveheart is a great film. One of my favorites and I've watched it many times. As history... it's hysterical.
Apparently though, Hollywood isn't the only one that does this. Shakespeare, it turns out, may have over-stated the odds in Henry V. To that end, some NY Times op-ed person thought to rewrite the famous speech. You know, the "hold their manhoods cheap" speech. Which, in turn, is the real reason for this post. I'm reasonably certain Shakespeare new his facts. I'm also reasonably certain he knew a better story when he thought of one. As fiction, mind you. I don't think Shakespeare ever made any claims to be a faithful chronicler of history, which I kind of thought the NY Times piece overlooked in it's mock-up of the speech.
If you're going to write history, actual factual history, then yes, you need to be accurate as much as possible. But if you're sticking that "Based On" label, or better yet the "Inspired By" in front of your work, I think you ought to be granted some leeway with the actual events.
So long as you're telling a good story.