The real history is usually messier than the movie. That’s the part worth reading.

Films need a clean shape: a hero, a villain, a reason for everything. Real events refuse to arrange themselves that way, which is why the actual account is full of mixed motives, decisions made in confusion and outcomes nobody intended. The mess is not a flaw in the history. It is the part that shows how things really happen, and it is exactly what a script has to cut.

Take a film about real events that you liked and read a few pages about what actually happened. Look for the bits that would not fit a script.