Great War

The Great War (大戦, Taisen), also referred to simply as The War (戦争, Sensō), is an event that appears in the Tales of RWBY series. It was a significant conflict that occurred on Remnant, the being between all of the Kingdoms located in the southern and western parts of the world on one side and the Kingdoms located in the northern and eastern parts of the world on the other side. It came to its conclusion eighty years before the events at the beginning of the series.

The Great War preceded the Faunus Rights Revolution, a conflict over racial politics, by several years. However, no specific time frame has been provided.

"On this day, nearly eighty years ago, the largest war in recorded history came to an end. It was a war of ignorance, of greed, and of oppression. A war that was about much more than where borders fell or who traded with whom, but about the very idea of individualism itself."
 * —Ozpin, on the Great War.

Tensions
The humans use a technology known as blastia, which is fueled by aer and was created by the ancient Geraios Civilization, a civilization of Krityans who can communicate with the Entelexeia, a wise, long-lived race that keeps the amount of aer in the world in balance. The humans greatly favored the convenience of the blastia. One day, a Krityan man known as Hermes invented the Hermes blastia, which was more powerful than the traditional blastia and absorbs several times as much aer. The combined aer consumption of the ever-popular traditional blastia, and the testing of the Hermes blastia brought the aer levels to a catastrophically low amount. If the level of aer could not be restored back to normal, it could awaken an apocalypse the Geraios named the Adephagos.

Seeing that the Adephagos was awakening, the Geraios built the Enduring Shrine of Zaude. This shrine was a large barrier blastia capable of shielding the entire world from the Adephagos. After building it, Krones, an Entelexeia, lifted up the city to house what is now Myorzo.

Uprising
Since then, there was high tension between the kingdoms, mostly caused by Mistral, which had allied itself with Mantle. The two traded frequently, with Mistral sending supplies and Mantle providing insight on how to settle the snowy northern region of Anima. After an incident with the Grimm, Mantle came to believe that, if it abolished the arts and repressed self-expression to control its citizens' emotions, it would be safer from Grimm. Rather than lose its alliance, Mistral complied with Mantle's wishes to an extent, banning the arts and self-expression everywhere in the kingdom except for within its central power. This added to the list of things that Vale disliked about Mantle and Mistral, which included the two kingdom's treatment of their own citizens, their use of slave labor and their insistence that their way of life was what was best for everyone.

Eventually, Mistral and Vale both set their sights on settling the islands and peninsulas on the east coast of Sanus. Despite what his citizens wanted, the king of Vale chose to share the land with the settlers from Mistral.

Outbreak of Conflict
However, the immensely high tensions ultimately resulted in a riot between the bands of settlers. It is unknown who attacked first, but this disagreement initiated and began the first battle of the Great War. Mantle quickly came to Mistral's aid, and battles were fought on both Sanus and Anima soil.

For a time, Vacuo remained neutral, due to Mantle and Mistral having established a presence in their territory in the years prior. When the two began pressuring Vacuo to ally with them, the citizens of Vacuo realized that if Vale fell, there would be no one left to stop Mistral and Mantle from conquering them. Vacuo rallied against Mantle and Mistral and pushed them out of the Vacuoan territory and allied themselves with Vale.

Overall, the Great War lasted for ten years. Blastia, Food and Dust rations were put into effect, development of technology accelerated, Humans and Faunus on the battlefield grew closer and Grimm attacks increased worldwide. Whenever the Grimm would invade a battlefield, the armies called a temporary ceasefire long enough to eradicate the monsters, before continuing to fight each other. Many settlements were lost to the Grimm, due to their best warriors being away to fight in the War, and most of those settlements were never reclaimed.

Events
The Great War took place across the world. The most notable area of fighting took place at Mt. Temza, which was the world's largest mountain and site of a Krityan city, Temza, as well as the home of Hermes and his sole daughter, Judith. With the area being a war zone, Mt. Temza, as well as the Temza, were reduced to a gaping crater in the mountain range. The two notable humans who died there in the war were Damuron Atomais, a member of the Imperial Knights and supporter of Commandant Alexei Dinoia, and Casey, a good friend of Damuron's.

Seeing that Damuron could be of some use, Alexei replaced his heart with a Hermes blastia and renamed the reborn Damuron "Schwann Oltorain", who would later take on another alias, "Raven". Many Entelexeia died in the war, most notably Elucifur, who fought alongside the humans. His close friend, Duke Pantarei, was a human, and he and Duke won the war. Unfortunately, the humans feared Elucifur's power and killed him, sparking Duke's hatred for his own race.

Approximately eighty years before the beginning of RWBY, the Great War came to an end during the Vacuo campaign, where Mantle and Mistral targeted Vacuo, hoping to cut off their enemy's blastia and Dust supplies by conquering Vacuo's mines. The king of Vale arrived and personally led his army alongside Vacuo's, thoroughly decimating the opposing forces. It is said that Vale's king, from then on nicknamed the Warrior King, laid waste to countless men on his own, but historians believe that this feat was aided by Vacuo's unusually violent weather patterns and Mantle's inexperience in desert combat. Ultimately, it was the deadliest battle of the entire war.

Resolution
Following this battle, the four kingdoms gathered on neutral ground on the island of Vytal, where they formed a treaty and planned the future of Remnant. Although the Kingdoms were ready to bow before the rule of Vale and it's Warrior King, he decided against it. Instead, the leaders redistributed territories, abolished slavery and restructured the governments. The Faunus were given equal rights and were gifted the continent of Menagerie for their own use in order to compensate for their previous mistreatment.

The Entelexeia, having nearly driven to extinction since from the war, harbors an underlying hatred toward blastia. The only known Entelexeia still alive during the events of the story are Ba'ul, Phaeroh, Belius, Gusios, Khroma, Astal, Krones, and Spiral Draco, king of the Entelexeia.

Vale's king founded the Huntsman Academies in each of the four kingdoms; Beacon Academy in Vale, Shade Academy in Vacuo, Haven Academy in Mistral and Atlas Academy in Mantle. He placed his most trusted followers in command of each academy. The intended purpose of the academies was to train Huntsmen and Huntresses, warriors whose sole purpose would be to fight the Grimm, and whose allegiance would not be tied to the kingdoms. Secretly, the academies were also given the task of safeguarding four Relics. Sometime after the end of the Great War, Mantle's capital was moved to Atlas, and the government, military and academy were combined.

Tales of RWBY
In "Field Trip", Professor Ozpin talks about the War in a speech to an assembly of students from all four kingdoms. He states that the War was the largest conflict in recorded history. Today, Remnant enjoys peace and "unity through diversity". This diversity is celebrated in cultural events such as the Vytal Festival, named after the place where the peace was brokered. Those who opposed the destruction of individualism made it a part of their legacy by naming their children after the fundamental aspect of art, color, to demonstrate that they and future generations would always oppose oppression, a trend that continues into the present era.

Jaune Arc reveals in "The Shining Beacon" that his sword and shield, Crocea Mors, were passed down from his great-great-grandfather, who used it to fight in "the War". The simplistic design of Crocea Mors in comparison to other weapons seen in the series may give some clues as to the nature of the weaponry used in the war.

In "A Minor Hiccup", Weiss Schnee explains that in the aftermath of the Great War, the Kingdom of Atlas developed and shared the Cross Continental Transmit System in order to allow the four kingdoms to communicate with one another more effectively.

Notes & Trivia

 * The War also provides an in-universe explanation for the "Color Naming Rule" of the Tales of RWBY universe. These guidelines, which was been set by Monty Oum, state that most characters and team names in Tales of RWBY must have a name that is either a color, sounds like a color, means a color or is otherwise evocative of a color.