Disguised as Ultramarines, Alpha Legion attempts and assassination of Roboute Guilliman on Macragge. Did they succeed or were their plans foiled?
Via our good friends at Lexicanum
After the virus-bombing of Isstvan III, the presumed loyal Alpha Legion was one of the legions sent by the Emperor to destroy Horus at his base on Isstvan V. Assigned to the second wave, the Legion instead turned on the loyalist first wave. It is thought by many that much of the traitors’ Isstvan V strategy was planned by Alpharius and the Alpha Legion.
When Raven Guard Commander Branne arrived at Istvaan V to retrieve several of what remained of the Loyalist forces including his Primarch – Corax – the Alpha Legion tried to help Corax escape, going as far as killing the commander of a World Eaters battle barge which could have delayed the superior Raven Guard fleet. The Alpha Legion had Apothecarii that were master of face transplantation. The took the faces of fallen Raven Guard to transplant them on their own Astartes. Together with the knowledge gained by digesting the brains of the dead Raven Guard, three Alpha Legion Astartes were able to infiltrate the Raven Guard Legion. Later about 50 Alpha Legion Astartes in the colours of the Raven Guard were sent as reinforcments for this agents. While Omegon could retrieve the data this infiltrators could optaion, all of them were killed by the Raven Guard. Learning of the Infiltration of the Raven Guard, Horus ordered Ezekyle Abaddon to find Alpha Legion agents in his legion at all costs.
During the Heresy, the Alpha Legion split off from the main body of Horus’s forces early and did not attack Terra, instead embarking upon a series of delaying actions in an attempt to hold Imperial reinforcements in place. A notable earlier example was attempting to block the White Scars at the Chondax System, but Jaghatai Khan was able to maneuver out of their trap. Alpharius or Omegon’s dubious agenda came to light at Chondax, where they were under orders from Horus to recruit the White Scars. Instead, the Alpha Legion fleet there engaged in hostile actions to seemingly provoke the Scars into a fight after blockading them long enough for them to get word from Rogal Dorn of Horus’ treachery. Indeed this message was only delivered because Omegon had dispatched forces to destroy an Alpha Legion-occupied Pylon array blocking the White Scars’ communications. Subtlety, the Alpha Legion or at least elements of it made sure that Jaghatai Khan would join the Emperor. Not even the Alpha Legion itself was spared from their own schemes. Alpharius was able to manipulate a strikeforce of Shattered Legionaires under Shadrak Meduson into eliminating a cell of seemingly loyalist Alpha Legion.
During the Heresy the Alpha Legion also engaged in smaller actions, defeating a White Scars force on Tallarn. During the Battle of the Alaxxes Nebula, the Alpha legion nearly succeeded in destroying the Space Wolves until the loyalists were saved by the Dark Angels. In addition, a squad of Alpha Legionaries disguised as Ultramarines under Aeonid Thiel nearly succeeded in assassinating Roboute Guilliman on Macragge.
Alpharius was eventually charged with Horus himself of spearheading the traitor advance into the Sol System. Alpharius himself led a large fleet against Pluto in the opening shots of the Solar War. During the battle, Alpharius was seemingly killed by Rogal Dorn but Omegon effectively took over his responsibilities.
Despite their contributions, however, Horus was ultimately defeated.
