The Great War Against Chaos was the moment the world came closest to falling. When the Chaos Wastes swelled and the daemon-tainted hordes of the north poured south under the warlord Asavar Kul, they threatened to sweep away every realm of the Old World in a single tide of ruin. Kislev burned, the northern provinces reeled, and the great fortress-city of Praag was subjected to horrors that scarred it forever.
Into that despair stepped Magnus of Nuln, called the Pious. A visionary touched by faith in Sigmar, Magnus rose from obscurity to rally the sundered Empire of Man, ending the Age of the Three Emperors by sheer force of conviction. He preached unity where there had been schism, and even reconciled the College of Wizards and the exiled Teclis of Ulthuan, who taught men to wield the winds of magic in ordered form.
The war reached its crisis before the walls of Kislev, where the united armies of men, elves, and dwarfs met the full might of Chaos. In a battle of unimaginable savagery, Magnus and his allies broke the horde and cast the survivors back into the northern wastes.
Magnus's victory did more than save the world — it remade the Empire. He was crowned Emperor, the provinces reunited under a single crown, and the Colleges of Magic founded. For two centuries after, the Empire knew a strength and unity unmatched since Sigmar's own age.