Kyrl Grimblood was a Wolf Lord of a Space Wolves Great Company during the Plague of Unbelief. Fenris, the world of the Space Wolves, lay in the path of Bucharis's conquering armies as they swept toward the heart of the Imperium. For three years Bucharis's armies assaulted the Fang, millions dying as the inhabitants of Fenris fought a long war with the invaders.
Grimblood and his Great Company had departed Fenris five years earlier on a mission into the Eye of Terror. He returned just as the besieging armies prepared for the final attack, Grimblood's Marines smashing into the rear of the armies, allowing the defenders of the Fang to break the siege. The fleet of Admiral Sehalla was forced to retreat out of the system, leaving the Guardsmen of Colonel Gasto stranded and doomed.