And who defines who are the victors and losers anyway? It isn't just down to who won what war funnily enough. At least not in fiction. You get to define who wins and loses. You get to define if there is a downside to the win. You get to show who fights back from a loss and perhaps becomes a more determined character than they might otherwise have done.
You get to show how history changed life in one direction but there's nothing to stop you looking at the same event from a different character's viewpoint especially if there is a dramatic change of emphasis. Why do your characters hold such opposing views? Who backs them? And if you have a world which can change time, how does that world handle history?
What is important to one character/culture in your world will not be so vital to others and that could be worth exploring too.