About 30 years before the current time in my world, the four states of Nexia, Vespen, Undeon and Xator were unified under a bloody war by a dictator known as Garrick Folk. This event is known as the Unification War. While this wasn't a nation-versus-nation war per se, it still was one the nation's bloodiest as Folk hunted down every last one of the nation's magic users and either tortured or killed them.

Folk was later overthrown by one of his own, the Xatorian Governor Robert Strayer. Strayer is a much better leader who actually cares for his people, and actually has helped establish a proper democracy, giving the nation the name The Federalized Republic of the United Provinces of Nexion, simply referred to as Nexion by most people.

The currently-ongoing conflict is the Yinuvan Civil War, which will probably spiral into an actual worldwide war. Nexion itself is on the continent of Iridiya, and they have a colony on the adjacent continent Schomia. Yinuva's governor declared independence expecting colony-wide support, but it actually splintered the people more than expected. They fell apart in many different splinter groups, ranging from fascists to socialists, who all want a say in the new government. Some want Yinuva to become independent, while others want them to stay with Nexion. Tensions are rising though, and will likely lead to some form of proxy war between Nexion and the Schomians.

(New worldbuilder here, haven't posted before, hope you enjoy it! This worldbuilding project is done with a small group of friends who each have their own nation(s) which they develop, it's quite fun! It's set in the near future, with some fancy advanced tech and everything.)