The son of the slain High-King Varag Skulltaker, Cormac harboured a soul-blackening hatred towards the newly ascendant Empire that had slaughtered and driven his people back to the barren northlands. His greatest resentment was reserved for the Unberogens and their king Sigmar Heldenhammer, who had led the charge against the Northern tribes. The molten core of violence within him, as well as his favour in the eyes of the Blood God, proved a potent force in unifying the scattered tribes of the Northmen; clad in his father's Chaos Plate and wielding a burning axe in which was bound the spirit of a daemon of Khorne, he was an avenging fury that laid waste to the enemies of his people.
In time, tales of Cormac's victories and strength reached to the eastern lands, drawing the Kurgan and Hung tribes to pledge their lives to his banner. In the year 9 IC, he led the Norsii wolfships to ravage the coastal regions of the Udoses tribe, before putting the town of Haugrvik to the torch and slaying all within as a sacrifice to Khorne. Cormac then led the Norsii to the Udoses capital and destroyed the castle of Salzenhus, personally slaying Wolfilla, chieftain of the Udoses, and crucifying him. The Norsii armies then marched unimpeded through the outlying Imperial territories, putting countless townships to the torch.
When the Emperor finally marshalled the tribes to face them, his army fared no better, and was forced to retreat to the city of Middenheim. The Norsii followed the battered remnants of Sigmar's army, intending to slay the Emperor and corrupt the sacred Flame of Ulric, thus destroying the faith of the Empire itself. The siege itself lasted over a dozen days. On the thirteenth, most terrible day of the siege, Cormac Bloodaxe, who had slain so many in battle that his axe now perpetually ran thick with congealed blood, awoke knowing the will of his god was to be carried out. For his vision seethed red as though his eyes were drenched perpetually in blood. Before a great pit where the Norsii had thrown the corpses of their enemies in honour of Khorne, there did Cormac command the greatest warriors of eight clans to sacrifice themselves to Khorne's glory. Mightily pleased with their valour and tithe, Khorne did take up the Norsii king and reforged him into a manifestation of rage - a Daemon Prince.
Cormac, in his new, resplendent form, is said to have strode forth and broken apart the walls of Middenheim with a single blow, slaughtering hundreds with sweeps of his burning axe while his very presence drove the men of the Empire mad with rage born of fear. The Norsemen roared their exultation to the cold thrones of the Gods, their cries now even more hideously animalistic than those of the Beastkin who stood alongside them, and they fought with fury so redoubled that none could withstand them - such was their joy to fight under the gaze of a living avatar of Khorne the Mighty.
Soon, the Daemon Prince crossed blades with Sigmar, the two kings fighting to decide the fate of their peoples. It was only through the aid of Myrsa, Warrior Eternal of the Fauschlag, and the divine power of Ulric himself, that Sigmar was able to marshall enough strength to defeat Cormac Bloodaxe, banishing the fallen king to the Realm of Chaos. With the banishment of Cormac, the morale of the Norsii army gave out, and they now fought their way past the vengeful press of Imperials to reach their wolfships and return to their new homeland. Though the Empire was ultimately victorious, the dreadful memory of how close it had come to desolation loomed long in the memories of all who had fought and suffered in the invasion; and few would ever forget the terror of the mighty Norsemen...
- 1: Empire (Novel) by Graham McNeill