I'm personally fascinated by history, but it's difficult for me to use this passionate love affair in my writing because I'm interested in real history and real historical figures. And if you write about real people in your books, even those who are long dead, you may experience backlash in all sorts of different forms. But other authors have learned how to beat the system, and they've done it so well there's an entire literary technique named for this sort of savvy trickery. It's called roman a clef, and you don't even have to be French to use it to avoid lawsuits and other author troubles.
At Their Own Game
Want to write about something real, but fear reprisal? Don't shrink from the story you want to tell. Pull a fast one on them, and use roman a clef.
This French term is used to describe a novel that is about real life -- real events and real people. This type of novel, however, is very thinly disguised as fiction. The trick is that the names are changed, and a key is added to the back of the book showing which "characters" represent which real people.
It's just that easy to beat the system. And it's been done time and time again by countless authors for all sorts of reasons.