Alpharius Omegon - Solar Campaign: With its network of secret operatives and bondsmen and women, it is believed that even during the Horus Heresy the Alpha Legion had the means and opportunity to transfer materiel and personnel between sectors, including the Segmentum Solar and the strategically vital Sol System, whose defence had been entrusted to the Imperial Fists and their primarch, Rogal Dorn, the newly proclaimed Praetorian of Terra. Under the tireless efforts of the Imperial Fists, the Sol System had become a fortress, each strata of the Solar System being turned into a perfectly organised defence zone to break the Warmaster's eventual assault. Given the Alpha Legion's need to prove its own superiority, it would not suffice to simply break open Terra's outer defences. They wished to humiliate the VIIth Legion, and to do so they would have to infiltrate the most secure location in the entire galaxy -- the Imperial Palace.Alpha Legion units placed into enemy territory were trained and conditioned to pursue broad mission objectives in whatever way they thought best. The scope of these objectives were called mission parameters. An Alpha Legion force or warrior might have been given a series of potential mission parameters before its infiltration, some of which might be radically different in shape: killing or protecting the same individual, for example. Each parameter would have a single activation word or phrase that would set an infiltrator off towards a set of objectives. A word spoken on Vox or scrawled on a slip of parchment was enough to change the direction of their action from one parameter to another. And it was not uncommon for members of the same force to be following different mission parameters.Activating assets that had been dormant and hidden on Terra for several solar decades, the Alpha Legion would eventually succeed where all others had failed before, infiltrating several agents into the Imperial Palace and especially the Investiary, where great statues had been erected to commemorate the Great Crusade's greatest generals -- the primarchs of the twenty Space Marine Legions.Two plinths had stood empty for a long time, the statues adorning them destroyed when their respective owners were cast to oblivion and their history erased -- the Lost Primarchs. But the nine statues of those primarchs who had turned against the Emperor had merely been covered up, as if they were still capable of being saved. This area of the Palace was to be the Alpha Legion's target. Infiltrated Legionaries succeeded in penetrating into the Investiary and destroyed all the statues except two of them -- those of Alpharius and Rogal Dorn.Intended as both a challenge and a message, this feat was deliberately kept secret from the other organisations within the Imperial Palace. Even the Regent of Terra, Malcador the Sigilite, and the Emperor's own bodyguards, the Legio Custodes, were forbidden by Rogal Dorn from entering the Investiary and witnessing the shaming of the Imperial Fists. By what means the Sigilite still discovered the presence of the Alpha Legion on Terra remains a mystery, but Rogal Dorn was adamant that he would deal with the treacherous XXth Legion in due course.Shortly after this act of sabotage an Alpha Legion fleet, led by Harrowmaster Kel Silonius, attacked the Sol System's outermost defences, and managed to capture several of Pluto's moons, which constituted the heart of the outermost defence perimeter of the Sol System. What truly occurred there remains a well-guarded secret, one kept by Rogal Dorn and his Huscarl bodyguard.