The Night of the Wolf is a little known incident that occurred shortly after the massacre of the entire planetary population of the world of Ghenna by the World Eaters Legion during the Great Crusade in the late 30th Millennium. The Primarch Leman Russ had been charged by the Emperor to take his Space Wolves Space Marine Legion to Ghenna to bring the World Eaters to heel. The two Legions met at Malkoya, on the fields beyond the dead Ghennan city of the same name.
The Space Wolves Primarch Leman Russ had been charged by the Emperor to take his Space Wolves Legion to the world of Ghenna to bring the World Eaters to heel after the World Eaters' genocidal rampage had wiped out the population of that planet during its Imperial Compliance campaign. The two Astartes Legions met at Malkoya, on the fields beyond the dead Ghennan city of that same name. The World Eaters, battered and bleeding from Ghennan Compliance campaign, formed ragged lines before the assembled Space Wolves Legion.
The Primarchs stood before their hosts, armed and armoured -- Angron awash with blood and carved up by fresh wounds; Leman Russ in resplendent battle-plate the colour of the storms on his tempestuous homeworld of Fenris. In these early years of the Great Crusade, Angron still carried his first axe, the precursor to all others. He called it Widowmaker. It would break this very day, never to be used again. Russ carried Krakenmaw, his immense Chainsword, toothed by some Fenrisian sea-devil from that blighted world's many myths. Angron refused to recognise his brother's authority, and warned the Wolf King to depart before the situation became something that he would regret. But Russ refused to be cowed by the warlike Primarch. He informed Angron that the implantation surgeries must end, for the Emperor Himself had deemed it so. The massacres of newly discovered human worlds were to end with the fall of Ghenna. The World Eaters were to submit to the Space Wolves as their escorts for their Legion's return to Terra. Once they reached the Imperial Palace, everything would be done to remove the parasitic Butcher's Nails implants from the World Eaters' minds. Angron was not amused by Russ' implied threats.
No one ever saw who fired the first shot. In the decades after, the World Eaters claimed it came from the Space Wolves' lines, and the Space Wolves claimed the same of the XII Legion. Without either Primarch giving an order, the two Space Marine Legions fought. The Night of the Wolf, it was later called. Imperial archives referred to it as the Ghenna Scouring, omitting the moment the World Eaters and Space Wolves drew blood. A source of pride for both Legions, and a source of secret shame. Both claimed victory. But both feared they had actually lost, and in truth, the battle proved bloody but inconclusive. But the World Eaters did not return to Terra, and Angron refused to stop the implantation of his Astartes with the Butcher's Nails.
Paying no heed to the Emperor's command, Angron ordered his Techmarines to continue to use the Butcher's Nails cortical implant technology until nearly every World Eater Space Marine had undergone the surgery. Blood rites like blood-drinking and vicious gladiatorial combats became an increasingly important part of the World Eaters' Legionary rituals and customs as they continued to slaughter their way across a broad swathe of the galaxy. It soon became common practice for World Eaters to compete in the number of skulls that they could take in battle. For some World Eaters Space Marines, the result was an uncontrollable thirst for slaughter even away from the battlefield. However, the results produced by the World Eaters on the frontlines were so effective that the Imperium --and its Emperor-- proved willing to turn a blind eye to the World Eaters' savage practices for quite some time during the course of the Great Crusade. This would prove to be a terrible miscalcualtion, as the World Eaters were already falling under the sway of the Blood God Khorne and would prove a ready ally of the Warmaster Horus once he began his great betrayal of the Imperium.
- Betrayer (Novel) by Aaron Dembski-Bowden