What is your "Great War" that changed (almost) everything?

The "World war" or "Great Auryrisian war", was the largest conflict in military history up to that point and included all the worlds major powers as well as a plethora of minor ones.

For years now, the power of the autocrats, the emperors, and the aristocracy had slowly been waning across the world as ideas of democracy and self-rule as well new ideologies and technology had swept the planet.

But by the time that Kyosodour had invaded the Utans, triggering a huge international backlash that inevitably led to war being declared most of these despots still had firm control of their countries and ordered the conscription of as many able bodied young men they could get their hands on.

The war was devastating, over the course of it's 5 year duration over 50'000'000 people would die, most of them from the lower and middle class. It was finally at this point that many peoples of the world decided to all cry out in one voice for freedom from oppression and the tyranny of empires, setting off the largest wave of revolutions to sweep the planet in world history.

This would go on to end the age of the empires, culminating in the fall of Kyosodour, Ostalia, the Tamaruk Murkhanate, the Northern Commonwealth, the Kingdom of Arseilia, and the Esparian empire.

Thus, despite the incredible loss of life a new republican age supposedly free from the grasp of autocrats was on the horizon.

Or at least it would have been, had the Toyhuyn Nayonate not launched a campaign of expansionist against it's neighbors. This is not to mention the outcome of Arseilia's civil war, as won by the nationalist party under August Gendarme who has sowed the rhetoric that they where betrayed by their supposed allies and suffered the most with little or nothing to show for it. Paving the way for a surge in nationalism and world tension as August has been securing allies and building up an army the likes of which has never before been seen.

Many fear what the future holds, and for good reason.

/r/worldbuilding Thread