During the Great War Against Chaos, Aurelion led a defense of Ulthuan against an army led by the Dark Elf Sorceress Lilaeth. When Lilaeth's army was destroyed, Aurelion chose to spare Lilaeth rather than kill her because she believed it would cause her more pain to live with her failure.
After the Great War Against Chaos was over, Aurelion travelled to the Empire and assisted the young Captain Stefan von Kessel in his efforts to purge the Empire of the remnants of Chaos. Ultimately, they led a defense of Talabheim against the Daemon Prince Thorgar the Blooded One, and vanquished the Chaos Hordes.
Following this victory, Aurelion remained for a time in the Empire, but was ultimately hunted down by Lilaeth. Lilaeth taunted Aurelion, claiming that there was no army to protect her this time. Following a short but intense duel, Lilaeth emerged the victor. Aurelion vehemently claimed that the Witch King would never sit upon the Phoenix Throne, and that Lilaeth's little victory meant nothing; Lilaeth responded by killing her and dedicating her sacrifice to Khaine.