Black Legion - Legion Command Hierarchy: As with all of the Space Marine Legions, Horus' command as Primarch over his own Legion was absolute. Beneath Horus were his Captains, beneath them were the squad Sergeants, and where a formation of squads came together for a purpose, the informal rank of "Chieftain" was given to the Sergeant granted field command authority, a matter not always of seniority, but rather selection of the best or most suited Astartes for the task at hand; an approach which fitted well within the Legion's pragmatic and sometimes impulsive approach to warfare.Beneath these non-commissioned officers were the rank-and-file Battle-Brothers of the Luna Wolves and the Sons of Horus. This simple hierarchy belied the truth of matters when applied in practice within the XVIth Legion. Within each rank, prestige and personal reputation counted for much within the brotherhood of Space Marines.There were distinctions between those who fought with the Legion for longer, between those who had fought in different campaigns, between those who had received certain honours, and between ordinary squads and those who formed a Captain's Honour Guard. Beneath the surface of this simmered other divisions, not easily visible to the outsider, divisions of blood and origin, divisions that the mere act of becoming a Space Marine should have washed away, but for the Sons of Horus did not in many cases. These hidden divisions would eventually bear bitter fruit.The rank of Captain within the Legion also held subtle variations of authority. Generally those in command of a lower numbered company outranked those in a higher numbered company, while those who had once had overall command of a campaign were considered superior to those officers he had commanded during that action. At the top of this informal but very real hierarchy of Legion officers were those Captains who served as Horus' closest advisors and in particular the First Captain of the Legion who commanded the elite 1st Company and also served as his Primarch's principal field officer and second-in-command.The senior-most Captains comprised the Legion's Mournival, the quartet of Astartes who served as Horus' closest advisors and companions within the XVIth Legion and who existed outside the regular command structure. Before the outbreak of the Horus Heresy, the final Mournival of the Sons of Horus included Captains Garviel Loken, Horus Aximand, Tarik Torgaddon and Ezekyle Abaddon. The Mournival served as an advisory body to Horus in both military and political matters, but in truth its members held no formal power above that of the other company Captains.Held together by Horus' personal charisma and brilliance as a leader, the command structure of the Luna Wolves and then the Sons of Horus proved highly effective, adaptable and resilient. Combined with the XVIth Legion's skill in rapidly concluding campaigns, it allowed the Legion to flow from one victory to another, forming and reforming to meet each new challenge.Each Son of Horus knew his capabilities and the capabilities of those around him, both by given rank and personal repute, capabilities that were enshrined in a hierarchy determined by deeds rather than the demands of military or ceremonial formality. Effective as it was, one cannot help but notice the importance of personal prestige and the pack-like sorting of authority as a hallmark of the XVIth Legion, and upon occasion the source of some conflict and vendetta within the ranks, a seed of the terrible division to come.As the character of the Legion was an echo of its Primarch, so one can perhaps see the flaw of the father in the pride of his sons. So it was that when Horus fell from grace, so too did his gene-sons, and their faults, long-sleeping, multiplied and grew to consume them: pride, ambition, the desire to be greater than any other and the savagery and merciless will to make such dark dreams manifest.