Brother turned against brother during the bloody days known as the War of Legions
The War of Legions was a conflict that occurred in the twilight years of the Empire of Stars, in which the Empire's fourteen Legions turned on one another, eventually leading to the complete collapse of the Empire.
This civil war had its beginnings in the crowning of Zaramoth the Unmaker as Stellar Emperor following the sudden, supposed suicide of Emperor Veransk III. Many suspected Zaramoth's complicity in this death, and even those who did not knew well of Zaramoth's brutal and bloody conquests across eastern Aranna. While thirteen of the imperial Legions initially swore their fealty to the Unmaker, the 10th Legion refused, fleeing far to the west rather than accept his claim.
The Azunite rebellion would also go on to stoke the growing fires of discontent, with many legionnaires joining Azunai's cause against the increasingly tyrannical Empire under Zaramoth. Zaramoth's death during his climactic duel with Azunai, coupled with the ravages of the First Cataclysm, finally sundered any harmony that may have remained between the Legions, turning the north into a war-ravaged quagmire for centuries afterwards.
Many Humans claim to be descended from the warriors of these legendary Legions, although some, like the Elves of Aman'lu, believe that the Empire's self-destruction was so thorough that none survived to pass on their heritage.