I was inspired to write this article when trying to read an execrable novel of historical fiction. The history had to do with the Irish rebellion of 1916 and the events leading up to it. The fiction mostly concerned the development of two repressed Irish Catholics's sex lives. The history was well researched and well interpreted. The fiction, however, was not well executed.
Upon giving up about halfway through the book, I did some thinking about blending history and fiction. After all, such blends are a major part of the fantasy/science fiction field, even constitution their own subgenres, historical fantasy and alternate history. Romance and mystery, and SF/F crossovers with these genres, often use historical settings as well. I asked myself: what approaches make such blends riveting, and what approaches turn out clunkers?
Most, if not all, of the following points apply to any blending of history and fiction, regardless of which subgenre it comes under.
Most SF and fantasy has a setting other than the here and now, so we're used to communicating unusual environments to our readers. Using historical settings involves two further considerations.
How familiar is the reader with the historical era? If you're writing for an American audience, then it's reasonable to assume that your readers have a basic grasp of the D-Day invasion of Normandy, the 1930s Dust Bowl, and the Constitutional Convention of 1787. However, even broadly educated readers may not be familiar with the Japanese invasion of China in 1937, the widespread famine in the 1930s Soviet Union, and the Belgian declaration of independence from Austria in 1789.
The less familiar your readers are with your setting, the more "explaining" you'll have to work into your story. A few readers will be experts on your setting, but don't worry about them. They will understand that most people aren't familiar with these people, events, customs, and locations, and they will be patient as the story brings them up to speed. On the other hand, don't be in too big a hurry to explain everything. SF/Fantasy readers are notably willing to wade deeply into a story without understanding a lot about the world, as long as it's a good story and as long as how the world works is revealed eventually. We SF/fantasy fans are also willing to learn about people, places, and events we'd never heard of before, so don't shy away from "obscure" (obscure to most of your readers -- not, obviously, obscure to the folks involved) history.
How much detail should you provide? Lots. It's as if you were setting your story on another planet, except that, ironically, you probably have to provide more detail. When reading about another planet, the readers only need to know enough about the world to understand the story. In historical fiction, however, the readers are seeking the special joy that comes from participating, albeit vicariously, in real events in real places with real people. It's fun to walk down a medieval London street in a Church processional or to give a speech in the Roman senate. Why is it so much fun? Because we're getting a chance, in effect, to time travel. So don't stint on the description -- it's at least half the fun.
You have some choices here, but whatever you do, your story must involve the characters as key players. If they're mere bystanders to events, even exciting events, then we readers won't be exciting. Just as in every other story, our protagonists must have opportunities to make decisions, take actions, and reach epiphanies (or fail to do so).
One choice is to choose an interesting era but involve your characters in a made-up "event" that never made the history books for some reason. Such an "event" must dovetail with whatever is in the history books. Pat Murphy's Nadya, Toni Morrison's Beloved, and F. Paul Wilson's The Keep are examples of this approach. Outside of SF/fantasy, Bernard Cornwell works well with this approach in his Napoleonic and American Civil War series. In his books, his protagonists usually do play key roles in major historical events, typically on very crowded canvases where their intrusion isn't noticeable. He sometimes assigns them a role played by other, real people (with apologies to the historical personages in the back of the book) and sometimes makes them the cause of an event that historians can't explain (e.g., Robert E. Lee's strategy being found by the North wrapped up with some cigars in a field).
Another choice is to change history and go forward from there. The catalyst for change can be outside intervention. For instance, in Harry Turtledove's Guns of the South, South African racist whites travel back in time with advanced technology to create a Southern U.S. in which they can live. In his WWII series, aliens attack Earth just as the war is turning against the Axis powers. Alternatively, the story can assume that an event that went one way simply went another, as in Steven Barnes's Lion's Blood, in which Socrates fled Athens and survived, setting off a chain of events that led to America being colonized by Islamic Africans.
Yet another choice is to use an historical era as a guideline but depart freely from it. For example, Katherine Kurtz's Camber of Culdi series takes place in a thinly disguised medieval England, where Catholic ritual and magic are one and the same but the types of political intrigue and warfare feel very familiar. Likewise, Jacqueline Carey's Kushiel's Dart series happens in a world that is clearly medieval-to-Renaissance Europe, Middle East, and Africa -- complete with Jews, Romany, and invading Germanic tribes -- but where the dominant European religion is polytheistic, the gods intervene, and some magic works.
Good rules of dialog still apply. We never want to write dialog the way people really talk -- it's nearly incomprehensible. When we convey dialect, we should use a light touch to keep the text readable and so as not to parody our characters. In historical work, the dialog shouldn't be too historical -- a few thees and thous go a long way. Likewise, just as with any other kind of story, we don't use dialog to infodump. Characters carry on conversations. They do not speak essays at each other to edify the reader, nor do they tell each other things they already know. "Hey Bob, the Romans have been dominating us for decades." Bob: "Yeah, but a lot of men have joined the legions and done well." Gaah!
Handling point of view (POV) in historical work can be challenging. The character of the period does not notice the same things we would notice. Deirdre the medieval mage will not think, "No one in the crowded inn had bathed for a month, and the place reeked of body odor." Unless mages have different bathing habits than other people, Deirdre smells just like them, and people have always smelled that way to her. We wouldn't think, "We entered the crowded nightclub, and everyone was wearing clothes. There was fabric everywhere."
At the same time, it's exactly those indigenous details, the ones that create the historic period, that our readers want (see "Setting" above). So what to do? If Deirdre has just come in from outside, her nose will get used to the smell of lots of bodies in the same way that her eyes will adjust to the dim light. She would remark that. She won't think about bathing habits, because that's just a given, but she might feel a sense of comfort from the smell of people. She might, for example, remember sharing a bed with her four sisters growing up and how close and safe their bodies smelled around her.
Plenty has been written elsewhere about researching historical settings. I'll just say this: if you want to write fiction but find yourself writing a history book instead, stop and reevaluate your approach.