Endless War
The Endless War was fought between the Empire and the Alliance for the right to rule Riftmoor.

The struggle for the throne began in the First Age, when the Wardens conspired to overthrow the King and seize power for themselves. Their rebellion was only partially successful. Though the King was gone, the victorious Wardens quickly turned against one another. The rebellion fractured almost immediately. From this division emerged the two great political leagues that would dominate Warden history.
The Empire consisted of the Lektro, Kryo, Geo, and Hydro Domains. They sought to preserve Imperial control of the throne, believing that they were the rightful inheritors of the power the Wardens had seized.
Opposing them was the Alliance, formed by the Bios and Ignis Domains, later joined by the Entro Domain. The Alliance believed that the throne had been stolen and now only force remained as a path for them back to it. Their struggle was therefore not simply to destroy the Empire, but to reclaim what had been lost.
Apart from these two powers stood the Aero Domain.
The Aero Wardens remained neutral through much of Warden history, refusing to permanently bind themselves to either league. Yet neutrality did not mean isolation. Aero Wardens continued to participate in the Imperial contests for the throne, and an Aero Warden who succeeded in claiming it was often regarded as having temporarily departed from their domain, until their reign was complete. The Aero Domain themselves maintained their neutrality even when one of their own sat upon the Imperial Throne as more often then not their homelands were intertwined with Alliance territory.
The first great turning point came with the Great Siege.
It was during this conflict that the Virborne were first witnessed upon the battlefield. Their appearance transformed the nature of warfare forever. What had once been a struggle defined primarily by political rivalry and border skirmishes became something far greater and far more destructive.
The Great Siege gave birth to the conflict that history would eventually call the Endless War.
The struggle expanded beyond individual domains and worlds, becoming an era-spanning conflict that would follow Warden civilization wherever it went.
As the Wardens expanded into Riftmoor and the Reach**, they carried the war with them.
New worlds were terraformed. New systems were populated. Yet wherever the Wardens established themselves, the old divisions followed. The Empire and Alliance continued their struggle across new frontiers, their wars becoming intertwined with the expansion of galactic civilization itself.
But regardless of its form, the conflict always returned to the same question:
Who had the right to rule from the Imperial Throne?
The Endless War finally ended only when the Wardens themselves vanished.
With their disappearance, the great political struggle that had defined their civilization lost its central purpose. The Empire and Alliance continued to exist, and some conflicts between them persisted. But what remained were only echoes.
The borders, rivalries, alliances, and hatreds created by the Endless War survived the Wardens who had begun it. The civilizations of the galaxy inherited a history shaped by a conflict whose origins had long since become obscured by myth and time.