Alpha Legion - Fall to Heresy: With such examples existing in the Imperial records, it is perhaps easy to see why the Alpha Legion sided with Horus when the Warmaster made his pact with Chaos and rebelled against the Emperor; their martial pride and Alpharius' avoidance of all his primarch brothers apart from Horus seemingly the catalysts for their downfall. Yet, the Alpha Legion's turn to Chaos was, oddly, something they chose for the sake of the Imperium.While undertaking a war of Imperial Compliance on the planet of Nurth some two standard years before the outbreak of the Horus Heresy, the twin primarchs were approached by a man named John Grammaticus, an agent of an alien organisation known as the Cabal. The Cabal revealed to Alpharius Omegon, as well as two other men, Peto Soneka and a psyker by the name of Shere, the outcome of Horus being named Imperial Warmaster of the Great Crusade -- the onset of the terrible interstellar civil war called the Horus Heresy.They then presented two psychically foreseen possibilities to the twin primarchs: If the Emperor won the impending civil war, the Imperium of Man would slowly decay over the next ten to twenty millennia until it and trillions of souls were ultimately consumed by Chaos. If Horus won the war, however, after "two to three generations" Horus would be wracked with guilt for slaying his father the Emperor and would ultimately obliterate all Chaos-tainted factions in the galaxy and humanity itself in constant warfare. Humanity would be destroyed in the process, but the Emperor's greatest foes, the Chaos Gods, would be all but eliminated because so much of their power derived from the inherent psychic flaws of humanity itself.At this point, both primarchs staggered back and screamed at the vision: "The Alpha Legion has always, always, been for the Emperor!" The primarchs ultimately chose to follow Horus in their belief that the ultimate destruction of Chaos was the choice the Emperor Himself would have made, yet their loyalties remained with the Emperor even as they swore their souls to Chaos Undivided. The Cabal may have been sincere in its desire to prevent the terrible onset of the stagnation and constant warfare for the Imperium of Man that the Horus Heresy would initiate or it may have intentionally misled the primarchs, as the support of a Loyalist Alpha Legion might have changed the course of the campaign in ways that would have precluded Horus from reaching the Emperor and mortally wounding Him.Instead, by supporting Horus, the Alpha Legion actually implemented the future for humanity they had sought to prevent. It is unclear whether the Cabal misunderstood their psychic visions, thus acting in such a way that they created a self-fulfilling prophecy, or whether they were actually agents of Chaos or some other faction with an interest in attempting to subvert an otherwise loyal Legion.The Alpha Legion's present battle cry of "For the Emperor!," when viewed in this light, is not the mocking insult of a Traitor Legion it was once thought to be. Rather, it is a testament to the Legion's devotion that they have stayed true to their cause for so long. It is thought that the Alpha Legion's true goal at present is to release the Emperor from His "prison" of the Golden Throne so the revelation made to them by the Cabal is fulfilled.