Event · M30
Meeting of Alpharius and Horus
The Meeting of Alpharius and Horus was the encounter in which a primarch of the XX Legion boarded the Luna Wolves flagship Vengeful Spirit and was received by Horus Lupercal as a newly found brother. In the conventional telling, a ragtag fleet of primitive fighters forced Horus’s intervention; the primarch made his way to the bridge, killing or maiming several Luna Wolves before Horus stopped him, and answered the Warmaster’s demand for a name with the words “I am Alpharius.” Horus is then said to have kept him for some months before sending him on to the Emperor on Terra. Head of the Hydra gives a different identity to the figure on that bridge. By its account the twins had already reunited, and it was Omegon who took the name Alpharius before Horus while Alpharius himself stayed out of sight, the better to keep their dual nature hidden even from the Emperor. Both versions agree that only one twin appeared openly, that Horus welcomed him, and that the Legion thereafter entered the Great Crusade under the Alpharius name.
See where Meeting of Alpharius and Horus occurred on the galactic map during the Horus Heresy.