Thousand Sons - Pre-Heresy Organisation: The organisation of the Thousand Sons before the coming of Magnus the Red is not currently known but it is recorded that they were not considered particularly different from the organisation of a typical Astartes Legion apart from their unusually high number of battle-brothers that possessed psychic abilities which resulted in the Legion possessing the most powerful Librarians during that era. When Magnus took over command of the Thousand Sons, he instituted organisational and hierarchical changes within his Legion.Line officers included the sergeants who led a squad-analogue unit called a "chantry," and lieutenants (junior centurions) and captains (senior centurions) who served as the sub-commanders and commanders, respectively, of a company-analogue unit called a "circle." Legion officers of higher rank, including consuls and praetors, commanded one of the nine "Fellowships" that togther comprised the entirety of the Legion. The Thousand Sons also utilised a unique and impenetrable chain of command derived from the hermetic teachings of Magnus the Red, wherein officers held multiple ranks in overlapping tiers of seniority and specialisation, including those of Fellowship, order and cult.Units known as "chapters" in some of the other Legions which contained approximately 1,000 Astartes were now referred to as "Fellowships" within the Thousand Sons. The highest number of Fellowships the Thousand Sons were able to field when they rebuilt the Legion following the return of the primarch was ten. However, at the conclusion of the particularly bloody Kamenka Troika Campaign where the Thousand Sons had lost nearly nine hundred Astartes, this effectively wiped out an entire Fellowship. Rather than rebuild the decimated Fellowship, Magnus decided to reorganise and maintain the Legion with only nine Fellowships. This organisation was referred to as the Pesedjet. The Legion's command structure was adapted in accordance with Prosperine philosophy and were now known as the "Rehati" (or the coven of Magnus), a secondary command-track in which the Legion's senior officers were ranked according to psychic ability and influence.As part of their training, all captains of a Fellowship undertook a secondment to another Space Marine Legion to learn its ways and further the Thousand Sons' understanding of the galaxy in their pursuit of knowledge. Khalophis had served with the Iron Warriors, a Legion he admired and ranked second only to the Thousand Sons. Phosis T'kar fought alongside the Luna Wolves, and never tired of regaling his brothers with tales of meeting Horus Lupercal, or boasting of his close friendship with Hastur Sejanus and Ezekyle Abaddon, the first primarch's closest lieutenants.Hathor Maat's secondment had seen him serving with the Emperor's Children in their earliest days as they fought alongside the Luna Wolves. As Hathor Maat told of his experience to his fellow captains, he had caught the Phoenician's eye with his perfectly moulded features, and had fought within his sight on many an occasion. Maat's proudest possession was an Oath of Moment carved by Fulgrim, and fixed to his breastplate as he took his leave to return to Prospero.Uthizzar's secondment had been amongst the shortest ever served, lasting a little less than a Terran year with the Space Wolves. Ahriman had spent five standard years with the Word Bearers, learning much of their Legion and methods of war.Magnus placed great faith in his subordinates, believing he had taught them well, that their powerful sorceries gave them the necessary tools to function independently of him. Before the Horus Heresy, individual Thousand Sons squads were not led by Veteran sergeants but by those who showed the most psychic promise. These "thrall-wizards" were apprenticed to more experienced sorcerers for their cabalistic training, but at the same time gained experience leading their fellow warriors in small units. While this practice meant it was rare for a Thousand Sons Astartes who did not possess some measure of psychic talent to become a ranking officer, it also meant those sorcerers who did gain prominence had considerable combat experience.As a result, the Thousand Sons, a numerically small Legion to begin with, rarely took to the field en masse. Instead they campaigned in smaller detachments under the command of sorcerers who often acted with much more authority independent of their primarch than the officers of other Legions. This past command experience has stood them in good stead as independent leaders of Chaos Space Marine warbands since the end of the Heresy, to the Imperium's considerable and continuing misfortune.