There was a war. It happened years ago, maybe even thousands of years. Characters refference it, especially if they took a part in it. Shell-Shocked Veteran never managed to get over with what he experienced back then. Phony Veteran, on the other hand, will never shut up about how many brave things he did on it. Sometimes people will reference to war to set some events in timeline – something happened few years before the war, or somebody did something after the war. Maybe people still have to deal with it's consequences. War was, and it left it's ugly mark on the world. But it's never shown to the audience. We never see a single flashback from war, never can get more than just a glimple of what happened. War will be referenced, but mysterious, unexplained. Why it happened? How it ended? What does all things that took place there, which of people talk like it should be obvious, mean? Never explained. War is only an mysterious event of the past, made mostly to add a bit of mystery and give people excuse for insane ideas. World War III can ofter be this, stories set After the End have thendency do do this with war that caused the end. Please, avoid shows refferencing to Real Life conflicts, we have much more informations about them that will be ever provided in the typical case of fictional conflicts mentioned here, so they cannot serve as so mysterious element.
- Star Wars: Legacy has conflict between Galactic Republic and Empire, whin by latter, who then got into the war with Sith.
- Clone Wars were this for first Star Wars Trilogy, until the prequels came, along two cartoons and lot of other things that explored it, ultimately subverting this trope.
- Time War from Doctor Who. It was never shown, we know only that it caused a lot of destruction and wiped out entire races, including Time Lords, whose last survivor was Doctor. Doctor has to deal with consequences of Time War from time to time and sometimes he or somebody else reference to some events of it, but it's still mostly a mystery.
- Star Trek has a lot of those.
- Third World War and Eugenic Wars all taking place on Earth and concerning only humanity. It was actually one war in Original Series, but was later divided.
- War between Federation and Klingons
- The Next Generation has war between Federation and Cardassians, which was responsible for creating Anti-Cardassian Marquis. Strangely, it wasn't mentioned in first seasons, only later.
- Earth-Romulan war ended as this, because Enterprise was canceled, before it could cover it.
- Both series of Battlestar Galactica has mentioned wars with Cylons.
- Silicate War, war with android revolution, taking place years before events of Space: Above and Beyond.
- War with Magogs from Andromeda which end caused Nietzschean revolution, that may count too, as it started at the begining of first episode. Episode then jumps 300 years in the future, to the main plot, not only skipping downfall of revolution, but also civil war among the ones who caused it, High Guard.
- Star Wars Knights of the Old Republic has Madalorian Wars – another mysterious wars we don't know much, despite that main character took a part in them and became well known war hero.
- Of course, all Fallout games have war that brought end of old civilization. We know why the war started and see how it ended, but not much more.
Hello, Unknown Troper. You'll need to get known to lend a hand here.