|The Compliance Action on the world of Nurth is not going smoothly. Despite the leadership of the particularly prestigious and accomplished Lord Commander Teng Namatjira and the presence of ancient and elite Imperial Army regiments, the native inhabitants seem to be holding off the Imperial forces with relative ease. |
Tired and stung by this turn of events, Adeptus Astartes reinforcement is requested, and granted. Astartes of the Alpha Legion, led by their Primarch, are tasked to the theatre. The Nurthene rebellion is doomed as a result, the majority of their armed forces bottled up in an enormous siege.
It becomes evident that the Alpha Legion do not operate as other Astartes Legions; they make great use of subterfuge, so much so that the Lord Commander was not aware of their presence and contribution to the campaign until they announced themselves. Subterfuge proves to be the order of the day in the Nurthene campaign, as it is discovered that a Xenos-augmented Human spy is loose in the theatre, attempting to orchestrate the complex plans of his masters...plans that included the manipulation of events that resulted in the Alpha Legion arriving on Nurth.
This spy, John Grammaticus, works for an organisation he knows as the Cabal, a group of Xenos species that apparently includes Old Ones. This Cabal is dedicated to the excision of the Primordial Annihilator, Chaos. Aware of the coming Heresy, they believe that the Alpha Legion represent the last chance to save the galaxy from the predations of the Chaos powers. To this end, they confer with the Primarch of the Legion, Alpharius Omegon, and sway him/them to their viewpoint. In order for Chaos to perish, Horus must win the Heresy. In order for that to happen, the Alpha Legion must side with him.