The Thousand Years War (La guerre de mille ans) was a series of conflicts between the Baillairgé Coalition and the Deseretan Union. These wars and battles changed the entire world of Aemissum as a whole and were beneficial to the creation of advanced technologies such as the SPE and marchant-char.

The conflict itself began around 5C 209 and ended in 6C 10. It was first instigated by Deseret, who at the time was actually a colonial power with control over much of the western world rather than the smaller, isolationist nation that it is now. Upon contact with the nations of the new world, they had been almost immediately hostile due to seeing their inhabitants as "sub-human" and viewing themselves as the rightful heirs to humanity's legacy. They had started the conflict as a means of re-establishing the empires of old humanity in the new world. The Deseretans had the unique advantage of still retaining what little history remained of the old world and additionally having access to advanced technologies such as the marchant-char (albeit these were often salvaged and utilized flash-powder weaponry such as cannons and bombards) and matchlock weapons.

For the first 300 years of the war, it seemed Deseret was an unstoppable powerhouse, being able to seize territory in the southern regions of Ouvrard and much of the islands surrounding Eurasier as well as establishing puppet leaders in the regions of Raas, Dingo and Ruita (then known as Zion). However, this changed sometime around 5C 531: You see, at this time the Deseretans were facing troubles in their homeland, suffering from lower birthrates and an outbreak of disease which had lowered their population from around 500 million strong to around 379 million. But things got worse when a schism occurred between their military generals as a result of the lowered population of the country and losing morale daily due to their constant failed attempts to secure the Dujardin and Vigouroux lines. Deseret's forces were split between three different generals, each of whom would often infight or attempt to outright sabotage one another at every turn. This infighting also resulted in their failures to quell the constant uprisings in their controlled territories such as the underground resistance movements in Ouvrard and Ruita, which resulted in Ouvrard successfully being able to regain control over the southern half of it's country from the Deseretans due to several successful espionage and sabotage campaigns.

In the words of a certain TV salesman "But wait, there's more!": It only gets worse from here, as Deseret's civilian population who were forced to be drafted into the war were growing tired of fighting, often resulting in them starting a few rebellions of their own. These factors left the once powerful Deseret a shell of it's former self.

The Baillairgé Coaliation, founded in 5C 435 between the major nations of Aemissum, seized the opportunity and eventually began to strike back against their enemies, achieving a series of victories against the Deseretan Union. It was upon the rediscovery and reconstruction of the ancient marchant-char that the Coaliation would unveil it's greatest weapons yet: The Pilots. Pilots were mercenaries hired on behalf of noble families, men and women who could change the entire outcome of a battle with their presence on the field alone. As few as one or two of these Pilots being deployed to the front was enough to stop just about anything thrown at them. Ouvrardi citizens around southern Ouvrard viewed these Pilots as almost godlike, with them becoming folk icons among resistance movements and being instrumental in regaining control over their former territory. Many took up their own nicknames and insigias to match this legendary status as well.

The greatest victory of the Coalition was the destruction of the Twelth Apostle in 5C 881, the largest luftdreadnaught in the Deseretan air fleets. The destruction of this vessel was one of the many events that would spell the end of Deseret as a colonial empire. Deseret would go from a colonial superpower with control over much of the known world to an isolationist theocracy over the course of almost 800 years, with their armies being stripped of any kind of offensive capabilities and being forcefully turned into a self-defense force that could only act in defense of their nation. Their territories would go back to the control over the nations of the Coalition. In addition to this, Deseret's once renowned luftdreadnaughts and airships were dismantled, with them only being allowed to operate 5 of them at any time to act as part of their self-defense force. (One carrier, two light recon airships, one luftdreadnaught and one radio-communications airship.)

The major powers of the Baillairgé Coalition, Ouvrard, Eurasier, Strelka-Laika, Keeshondi and others, on the other hand would emerge victorious, becoming industrial powerhouses and strengthening their ties with one another. Eventually, the Coalition would become sort of a United Nations-esque group, albeit without it's own soldiers and acting more as a unified board for the peace and prosperity of nations underneath their alliance.

The Coalition's victories in the Thousand Years War would be far more beneficial to Aemissum, sparking the on-going era known as the Second Industrial Age. The technologies they had been inspired to develop or reverse engineer from the archives of old humanity and Deseret are used the world over. The most important piece of technology to emerge was the Spirit-Exploit Engine (SPE): An engine that can generate nearly infinite energy through constant recycling and recharging of souls/spirits transferred within. A single one of these SPEs can power things from marchant-char, cars, even entire cities.

Although the war ended officially in 6C 10, talks to end the war were started as early as 5C 984 with the first initial signing of the Treaties of the Baillairgé in the city of Orleanii in Ouvrard and others being signed in the Great Salt Lake of Deseret, which would relinquish the territories Deseret had taken over back to their former owners in the Baillairgé Coaliation, with Deseret having the afforementioned self-defense force pushed in to replace it's armed forces. Additionally, the Treaties forced all nations of Aemissum to willingly dismantle any form of soul cannon or similar weapons deemed as "extinction-level weapons" to ensure the safety of future generations. While the disarmament of extinction-level weapons and the dismantling of Deseret's armed forces were steps towards a more peaceful world, this obviously didn't put an end to wars or conflicts across Aemissum.


AFTERMATH:
It's been nearly 57 years since the war ended. The world has long since healed, but the scars still remain fresh for the surviving veterans and war refugees. It was a multi-generational conflict, one that saw the erasure and destruction of history the likes of which hadn't been seen since the End of Eras. Cities and villages were erased in the blink of an eye, ancient monuments and relics of the old world destroyed by artillery and gunfire.

With all of it's destruction, the war also brought innovation: The beginning of the Second Industrial Age would bring with it technologies such as the Spirit Exploit Engine, the marchant-char, radio and other forms of technology were brought to the general public, soon becoming widely adopted by the industrialized world. Monarchs and their royal lineages came into question, with many forgoing the idea of a monarchy in favor of republics. Others relegated their monarchs to serve less powerful roles as presidents and reformed themselves as constitutional monarchies. With widespread industrialization and urbanization, urban society would split from the rural, creating two vastly different worlds for their residents. The Second Industrial Age promises itself to be one of the most important timeframes in the history of Aemissum.