Alpha Legion - A War in Shadow: Once the Great Crusade was fully underway after 798.M30 and the first of the great Expeditionary Fleets had set out en masse to bring unity to the galaxy, the XXth Legion disappears from official history for many solar decades. However, there seems to be a connection between them and certain shadowed events during the Great Crusade that have never been adequately explained by the official record, even to what was known to the highest echelons of the Imperium, including even the Throne of Terra itself.Some suggest that during this time the XXth Legion, without their lost primarch, had a secret role to play in ensuring the Imperium's future. It has been suggested since the earliest days of the Great Crusade and the Emperor's great vision of a united humanity free of the shackles of torment of nightmarish enemies, as well as the threat of enemies without, there has remained the danger of the enemy within as has been proven time and again.Evidence for this hypothesis can be seen by the fact that the nascent Imperium of Man was plagued with rampant insurrections, petty rebellions and the dangerous plots of Renegades and Traitors. Such enemies had slunk into shadowed obscurity following bitter defiance and crushing conquests during the bloody wars of Unification, but yet plotted vengeance. Many were twisted by lust for power or tainted by exposure to the horrors beyond, and sought to pervert the Imperial Truth to their own ends.None thought that such hidden foes could strike at the heart of the Imperium until the so-called "incident" that reached into the Astartes gene-seed reserve that was nearly to doom the IIIrd Legion (the future Emperor's Children) occurred -- an act which many have since attributed to the actions of a secret enemy within. It was not long into this dark event in the fourth solar decade of the Great Crusade (ca. 838.M30) when the IIIrd Legion's gene-seed was tainted by a terrible viral blight that scattered and unspecified reports of anomalous Space Marine Legion activity came to light.These actions were uniformly tactical scale operations, which occurred far from the front lines of the Great Crusade by small detached units, ranging between squad and company in size. The warriors who carried them out were doubtless of the Legiones Astartes, identified by their power, abilities and wargear, but their identity remained concealed. These mysterious Legionaries carried little or no unit markings or heraldry, or in some cases wore unrecognised markings not in the official record.In some stranger instances they operated under a "false flag", wearing the livery of a known Legion, often amid a war zone where that impersonated Legion was operating but without that Legion's knowledge, license or command. These actions were uniformly of a covert nature; surgical strikes, assassinations, espionage, sabotage, the recovery of unknown artefacts and the abduction of important individuals or entire groups for some unknown purpose. Such strikes, carried out both at the front lines and within the already Compliant worlds of the Imperium, were deadly accurate and seldom left any witnesses alive to tell directly of them.The predations of what came to be known in certain circles as the "Ghost Legion" were rare -- at least those that came to light were few -- and protests by local Imperial commanders or Planetary Governors against them were rebuffed or simply ignored. It was suggested by some within the Imperial High Command that the XXth Legion was at work, but as other, specialised agencies of the Imperium such as the Legio Custodes, the Securitas Inconcensus and the Officio Assassinorum rose to power and established themselves, aspects of this unknown force faded and began to enter myth, although they never entirely disappeared.If such a "Ghost Legion" existed as a coherent entity, then it represented the frightening prospect of a Legiones Astartes force whose specialisation was to act in a way that was distinctly different from its peers, and to do so in secret. If this force was indeed the XXth Legion, then it may have been operating in the shadows of the Imperium for more than a Terran century, building a wealth of influence and experience akin to any other Space Marine Legion and undertaking a secret war at once part of and parallel to the Great Crusade itself.What it became, what it learned during these years remains unknown, but even if this supposition is true and not merely a conspiracy theory fashioned after the fact in regards to what was to follow, it poses yet another question -- why was the purpose of this "Ghost Legion" in its particular role ended? Had it simply been replaced by more specialised and newly founded Imperial powers, or had it become perhaps too unpredictable, uncontrollable or even too dangerous in its current form?Had the Great Crusade's need for front-line battle Legions to add to its war effort proved too great to allow the XXth Legion to remain in the shadows, or had the long awaited discovery of their primarch necessitated the change? Irrespective of the truth, the twisting coils of the Alpha Legion rose from the darkness and into the light of the Imperium.