Sanguinius, also sometimes referred to as the Angel during his lifetime, was the Primarch of the Blood Angels Legion of Space Marines. He was killed during the climax of the Horus Heresy during the Battle of Terra defending the Emperor of Mankind from the Warmaster Horus aboard his flagship, the Battle Barge Vengeful Spirit. Though Horus slew Sanguinius, who had once been one of his closest friends amongst the Primarchs, legend holds that it was the chink in Horus' armour created by the Angel that allowed the Emperor to slay the Arch-Heretic and thus prevent Mankind from falling to the corruption of the Ruinous Powers of Chaos.