I've been thinking about historical fiction and nonfiction. From a plotting perspective, they're unusual in that we usually know how the story ends. We know how World War II came out, what happened to the Hindenburg, and when Vesuvius erupted. The writer's challenge is to create tension in the face of a known ending. Sometimes writers choose historical mysteries for that reason, or historical figures about whom very little is known, so they can create a world from plausible conjecture. Sometimes they create tension around the fate of individual fictional characters--for example, we may know how and when a war ended, but we don't know whether the characters we've been following will survive it.
The inevitability of known outcomes is also tough to keep out of the characters' minds. When we readers and writers know how things come out, it's tempting to think the characters should know it, too. But when I look at the world today, I have no idea how things will go. Many historical events only look inevitable in hindsight, and I think that sense of uncertainty, that sense that anything could happen, is crucial if difficult to capture.