Ask any reader or Google the question:
and for the most part you will get the answer of “very”.
It’s true that there are some who believe that authors aren’t teachers. That it’s not our job to educate readers on events or time periods. However, you have to still argue that with why even write historical novels if you are going to take liberties with fact? Isn’t that the point of writing (and reading) historical novels? To travel back in time? Of course, with this I know that authors can’t be 100% accurate all the time. But, I do think that we should try to be mindful of our writing.
Word of caution when choosing to fiddle with historical face. While Hollywood can get away with messing up facts in order to create good fiction, writers and authors have to tread a little bit more carefully when blurring the lines. Movies like Braveheart are praised (even if mocked for its historical inaccuracies), but had it been a novel? That author would have probably been strung up by his/her toes.
Sure you can mess with some details when creating your fiction; however, you have to keep it within reason. For example, changing the dates of a war? Okay. Changing who won the war? Yikes. No, just no. *Of course, this rule doesn’t apply if you are writing an alternate historical novel.
Depending on the era of your novel, you should also be mindful of bringing in real-life people. Messing around with characteristics and behaviors can be tricky if there are living relatives and descendents who will take offense to how their ancestors are portrayed.
Elements to Historical Fiction and Historical Romance
Rules for Historical Fiction and Historical Romance