As usual, now that I've gotten my hands on a copy of the Journal Tactica: Skitarii: The Steel Hand of Mars, I'll be summarizing the lore in detail. That's what we're here for - the lore!
The journal tactica opens with the difference between the Skitarii's oaths and the Legiones Astartes - unlike the Space Marines, the Skitarii are sworn to safeguard and recover technological relics. Unlike most armies, who either served the Emperor or the Warmaster, the Skitarii only answer to the Fabricator General of Mars, though who they acknowledge as the Fabricator General is often up to debate. Their mission is to explore the galaxy, recover valuable technological relics, and bring them back to either the vast halls of Olympus Mons or the vaults of Phobos.
Divided into Conclaves, each Skitarii Conclave is dedicated to a specific aspect of the technological spectrum that formed the Mechanicum's core beliefs, e.g. atomantic power, plasma technology, or even xenos relics. Each Skitarii Battle-Pilgrym begins as a human thrall tithed from a forge-fane across the forge worlds in the Imperium, wherever the conclaves land and need to recruit as required. They undergo the Flesh-shriving, which augments their bodies with the augmetic armor known as Corpus Skitarii, which includes the locomotive prothestics and allow them to survive toxic environments. Their memories are also overwritten by engrams and they're subjected to hypno-indoctrinated training to turn amateurs into veterans, and also allowing the Marshal's memories to download into his successor.
They're more like light infantry who move at incredible speeds across any terrain (thanks to those long legs) and packing heavy firepower, which markedly differs from the attritional warfare that marked the doctrines of the Solar Auxilia and Legiones Astartes.
The Skitarii convlaves' origins date long before the formation of the Cult Mechanicum, the corpus-skitarii's augmetics based on adaptations used by ancient migrant scavenger clans that once roamed Mars. Back then, Mars was haunted by ferocious cy-carnivora and other technological abominations, so these wanderers survived by outrunning them, quite literally. They also recovered ancient technological artifacts, which helped in laying the foundation of the modern Mechanicum, and in honor of their service, they were inducted into the personal service of the first Fabricator General. Over time, they would grow into a mighty force wielded by the Fabricator General, organized into conclaves - small self-sufficient armies capable of operating far from Mars for extended periods of time with limited support. However, Skitarii are not Tech-priests, and so they are not trained in handling, operating, repairing or replicating tech-arcana. Separate from the Cult Mechanicus, they cannot control or use the relics they recovered, and instead simply bring them back to the vaults of Phobos.
During the Horus Heresy, there are about 30 conclaves. All the conclaves are supposed to be under the command of the Arch-Ordinator, the princpal ruler of the collected Skitarii Conclaves and answerable only to the Fabricator General of Mars. The Skitarii Conclaves are defined within the Imperial record as the
"Ancient standing armies of elite cybernetically and geneically engineered troops originating on Mars and principally loyal to theoffice of the Fabricator General." They are bound by specific Clade Parameters that govern their coded doctrines in battle, which is the sub-faction rule that gives us Line, Vanguard or better Deflagrate.
Each standard Conclave is divided into 16 individual Themata (the Skitarii equivalent of regiment), which are further subdivided into 22 Lochos (I assume battalions? They seem too big for company). Each Lochos is further subdivided into 12 corpus of Skitarii (squads), and these are commanded by a Skitarii Marshal while consisting of 16 Sktarii Battle-Pilgryms. They are supported by Armored Contingents that include Conveyor and Venator units held at the themata level and assigned to the commanding Marshal, as well as Bonepicker Hosts.
So basically, one Lochos, which is composed of 12 corpus of 16 Skitarii Battle-Pilgryms, contains approximately 192 Skitarii Battle-Pilgryms. I haven't even countered the Skitarii Marshals yet. A single Themata, made up of 22 Lochos, would bring that number up to 4,224 warriors. Since one Conclave comprises of 16 Themata, that means a single Conclave can muster up to 67,584 warriors. That's a lot! Given that there are about 30 Conclaves during the Horus Heresy, that would mean we have around 2,027,520 Skitarii Battle-Pilgryms. A significant force that outnumbers the Legiones Astartes, to be sure, but still very few when compared to the billions of Solar Auxilia and trillions of Imperial Army soldiers.
The clade paraneters are the following:
Incursus Clade (Ad membra fenax): Aggressive response against an enemy.
Excipio Clade (Acquisitor et cognitio): Acquisition of technological relics.
Speculor Clade (Occulus omnisior): Spies and scouts.
Vigilus Clade (Contra cladem): Protection, defense and custody of the vaults of the Mechanicum.
So we have Loyalist Skitarii and Traitor Skitarii. How did that happen when they're supposed to loyal to the Fabricator General? Well, as mentioned in the Loremasters post I did the other day, the engrammatic commandments are "The Skitarii serve the Fabricator General, the Fabricator General serves the Mechanicum." When Kelbor-Hal ordered the slaughter of perceived enemy Magi and the destruction of their forge-fanes, carrying out the Death of Innocence, they realized that Kelbor-Hal no longer served the Mechanicum, having forfeited his position as Fabricator General by his treachery. Logic dictates that their loyalty passes to his successor, Zagreus Kane. A full third of the Skitarii Conclaves have reassigned their loyalty to Zagreus Kane - the Fabricator General in exile, and through him, the cause of the Emperor.
The Traitor Skitarii are those who remain loyal to Kelbor-Hal, and because of the Loyalists who reassigned their loyalty to Zagreus Kane, he seeks to retain their loyalty by infecting then with scrap-code. This warps their engrammatic coding and prevents them from betraying Kelbor-Hal and the Traitors, and they become more erratic and prone to macabre displays, anointing their corpus-skitarii with blood of the slain. They are deployed by Kelbor-Hal ti reciver artifacts and relics of Old Night for Horus, to use against the Imperium.
The Skitarii Battle-Pilgrym Marshal is selected from the most compatible and veteran ordinators within a conclave, leading the warriors of a battle pilgrimage and acting as both field commander and representative of the Fabricator General's authority. This allows them access to sanctified relic-arms, including the auctorit scepter. The bulk of the nomadic contingents of the Skitarii Battle-Pilgryms are organized as conclaves, each war formation led by an ordinator, who is the equivalent of a sergeant.
Skitarii are warriors dedicated to combat, so they can't do other roles like repair and engineering. They can only perform the most basic of maintenance on the wargear forged for them, and they are dependent on the aid of forge worlds, an ancient and intended limitation on their power to keep them bound to the service and protection of the Mechanicum.
The Bonepicker Host is also known as the hosts of Ostologoi, hordes of numberless individuals who salvage armaments and armor from battlefields. Vultarax stratos-automata are employed primarily in a scout-surveyor role, retrofitted with additional auspex scanning arrays to search for relics while serving as mobile fire support to provide cover and suppress enemy forces.
Thankfully, the Skitarii Ordinator has the authority of the Fabricator General, so they can request the assistance of any magos of the Mechanicum to supply them with arms, munitions and support, as well as access to the forge world's factorum, warriors (e.g. Legio Cybernetica automata) and arsenals, but in a diplomatic manner that provides the service of their warriors in exchange...as long as it aligns with their retrieval mission or scouring xenos raucers, of course. The wandering Skitarii are able to accumulate a wide variety of transports and tanks, some incorporated into their ranks permanently and others on loan from the Magi. These include the Triaros Armored Conveyor, Krios battle tanks, Krios Venator tank destroyers and Karacnos assault tank.
The Triaros is a heavy transport found on every Forge World and its combination of heavy armor, potent weapons and a built-in flare shield allows it to serve as the mainstay transport of the Skitarii's infantry conclaves. Their familiarity across the Mechanicum also ensures that repairs and replacements can be easily conducted during campaigns. The Skitarii also makes use of the long-range phosphex mortars fired from the Karacnos, which is protected by heavy frontal armor and layers of defensive energy shields.
The compact Krios tank is protected by layers of energy fields rather than simple bulk armor and powered by a fusion ppower plant capable of accelerating it to incredible speeds. For the Skitarii, it serves as a rapid response and flanking unit that can outpace most other armor and outgun lesser units. Its systems are too complex for simple servitors or cybernetica cortexes, and so a Tech adept is integrated into the chassis to pilot it. The Krios Venator trades the lightning cannon of the more common Krios for a pulsar-fusil, a dedicated anti-armor weapon. Combining speed and firepower, the Skitarii uses the Krios Venator to intercept heavy armor.
The Journal Tactica also includes three battles detailing the involvement of the Skitarii. The first is the battle fot Vault Tharsis Deca-nine, where the Imperial Fists under a Space Marine Vigilator named Korben Talar clashed against the Skitarii of Conclave Speculor-Gamma-Mu. Two Imperial Fists Thunderhawks were taken out by anti-aircraft fire over the city of Mondus Gamma, but while their Captain is killed, Korben Talar took command of the survivors to fortify Vault Tharsis Deca-nine against the 600 warriors of Skitarii Conclave Speculor-Gamma-Mu.
At first, the Skitrarii wiped out the Castellax battle-automata and servitor-turrets guarding the vault, only for the Imperial Fists to show up and assault them. The Skitarii are forced into a retreat, but they have numbers on their side. Though the Inwit Imperial Fists fortify the place, using Castellax wreckage as a barricade, the sheer numbers of the Skitarii eventually overwhelm the stalwart Imperial Fists, and even Korben Talar is slain by the Skitarii Marshal, Speculor/4/11/θ/Tharsis. They are about to recover the dreadful weapon within the vault to unleash it upon Horus's enemies, but Talar has left one last gift to them - melta bombs. Unfortunately, Speculor/4/11/θ/Tharsis and the Skitarii only know how to fight, so they don't know how to defuse the melta bombs, and while Speculor/4/11/θ/Tharsis stays behind, the other Skitarii are forced to retreat. The melta bombs blow, burying both Speculor/4/11/θ/Tharsis and technological relic/dread weapon under tons of broken rock.
The survivors of Conclave Speculor-Gamma-Mu elect a new Marshal, then lop back out to the wastes to seek other lost vaults.
The second battle is the Loyalty Paradox, where the Skitarii warriors of Conclave Incursus-Lambda-Psi infiltrate Phobos to claim its relics in the moon's vaults. There's a reference to Order 66 from Star Wars, but as General Order Omega-99, which basically is an encoded binaric transmission to Skitarii to forewarn them of the Death of Innocence. It is here where the Skitarii no longer acknowledge Kelbor-Hal as the Fabricator General, especially Incursus-Lambda-Psi.
After entering Phobos, they massacre the Tech-thralls, then overwhelm the automata and simple servitor defenses protecting Phobos's fortifications. They eventually run into significant resistance in the form of Conclave Vigilus-Alpha-Omega, their fellow Skitarii querying them. Incursus-Lambda-Psi appeals to them by claiming that Kelbor-Hal has forfeited the role of Fabricator General and no longer serves the Mechanicum, the logic stipulating that Zagreus Kane is the Fabricator General now. Unfortunately, even if that logic holds, Kane has not issued any order to them to open the vaults of Phobos, so Vigilus-Alpha-Omega is unable to comply.
After the debate, they end up shooting each other. Ouch. This is the first Skitarii versus Skitarii action ever. Vigilus holds the advantages of superior numbers and prepared positions, and so the Incursus warriors are wiped out. However, it turns out that the main assault by Incursus-Lambda-Psi is a mere diversion. While Vigilus-Alpha-Omega annihilates the Incursus warriors in their last stand in Reliquary Vault 19-C, a much smaller, elite force has infiltrated an ancient tertiary vault and retrieved the sarcophagus of the first Fabricator General. They carry off the sarcophagus to their ships and set course for Terra, for Zagreus Kane and the court of the Emperor, aware that this relic is a symbol of authority for the true Fabricator General.
In the Coronid Deeps, the Sons of Horus landed on the isolated world of Cambrae to steal a relic buried beneath the obliterated ancienty city of Mithras, which survived Old Night. However, Blackshields allied to the Forge World Mezoa - the Disciples of the Flames - show up and attack the Sons of Horus. A Skitarii Conclave, Expurgis-Zeta-Phi, loyal to Mezoa and by extension Zagreus Kane and the Emperor, also appear to assist the Disciples of the Flames.
Though the Sons of Horus are elite and wear power armor, the Skitarii outnumber them, and overwhelm them with sheer numbers. The Praetor leading the Sons of Horus manage to counterattack, only for the Skitarii's Karacnos to show up and bombard the surviving Sons of Horus, annihilating them. The Skitarii then recover the technological relic underneath Mithras, leaving the Sons of Horus stragglers to the vengeful Disciples of the Flames, who engaged in an inefficient activity known as...hunting them for sport?
By the way, this relic is the Rhadamanthus, or The Judgement of the Dead, a black metal sphere 3 meters across and studdded with coolant hoses and ewreathed in a haze of steam. What does it do? Is it a weapon? No idea. One thing is for sure, it's a bloody macguffin, and an excuse for Loyalist Skitarii and Blackshield allies to fight Traitor Legiones Astartes. That's all I can say.
We also have a few notable events. The Death of Innocence should be familiar to everyone by now, but the Skitarii-focused narrative reveals that a third of the conclaves stayed loyal to Zagreus Kane, but are hunted down and destroyed. Fortunately, they are able to survive and either escape off-world in commandeered ships or continue a guerilla resistance in the MArtian wastes. A few conclaves arrive on Terra, following the heels of the Imperial Fists who evacuated Zagreus Kane, swearing their loyalty to him and dispatched to aid Loyalists in distant warzones.
The Word Bearers stupidly attack the Iron Hands' homeworld of Medusa after Ferrus Manus's death, landing several allied conclaves of Skitarii to raid the Keys of Hel. Though they succeed, it is a pryrhic victory for the Traitors, for they lost many of their forces to claim a small number of dangerous relics in Ferrus Manus's vaults, and this ends up galvanizing the previously disarrayed Iron Hands into launching the War of Bitter Iron.
On the other side, the World Easters and their Dark Mechanicum allies from Sarum assault the nine hollow worlds of Lastrati, a distant outpost of the Lucian Mechanicum. Four conclaves of Skitarii, pledged to Zagreus Kane, including Conclave Vigilus-Gamma-Phi and Conclave Incursus-Lambda-Psi (same one as the conclave who assault Phobos above) stand alongside Legio Astorum. Angron (in his Daemon form) and his flagship, the Conqueror, show up to land a ground assault, and the World Eaters basically slaughter the Loyalists in the system. Ouch.
Apparently, the Loyalist Skitarii Conclave Vindicor-Kappa-Delta goes missing when traveling to the forbidden world of Rangda for unknown reasons.
Cyraxus gets a mention here (man, I wish Fires of Cyraxus is a thing). Loyalist Skitarii conclaves in the Ultima Segmentum begin stockpiling recovered techno-relics on the remote forge enclave of Cyraxus. Starting as a research station within the Dominion of Storms, Cyraxus became one of the largest armories in the Segmentum by the final years of the Horus Heresy, but its location was llost after the battle for Honorium.
The end of the Mechhanicum and official appointment of Zagreus Kane of the new Adeptus Mechanicus, raises concerns regarding the loyalty of Skitarii serving the Loyalist cause, because they're afraid they might not welcome the change.
Phobos is raided by a coalition of Loyalist Skitarii Conclaves during the Siege of Terra. Having learned their lessons last time when Incursus-Lambda-Psi attacked, the fortress moon's defenses have been improved, including Traitor Skitarii, who have been transformed by Kelbor-Hal into warped and twisted creatures. The Loyalists fight fervently to cleanse the moon, but what they expected to be a temporary victory becomes permanent because Horus is slain by the Emperor shortly after. Unfortunately, they discover that many of Phobos's relics have long since been removed by the Traitors and transported to distant strongholds.
If there's one thing that annoys me, it's the whole nonsensical "the vast majority remain loyal to Kelbor-Hal" and "most of the Loyalist Skitarii (aligned to Zagreus Kane) are hunted down and destroyed." Like, they keep hammering us with how few Loyalist Skitarii there are, with most annihilated, and almost all Skitarii being Traitor (Kelbor-Hal aligned), but then you have a bunch of accounts of Loyalist Skitarii. I get the Phobos one, but the Cambrae/Mezoa Skitarii,
four conclaves showing up on Lastrati, an entire Loyalist conclave going missing on Rangda, Cyraxus, and a coalition of Loyalist Skitarii Conclaves during the Siege of Terra? Does that sound like "hunted down and destroyed" and a "mere handful" of Loyalist Skitarii to you? Where are all these Loyalist Skitarii Conclaves coming from? Does Zagreus Kane have some secret lab on Terra where he keeps churning out entire Skitarii Conclaves to send all over the Imperium or something? Something's not adding up.
It would be much better to simply state that most of the Loyalist Skitarii Conclaves are able to escape the Death of Innocence on Mars, and/or that Kane and other Loyalist Forge Worlds are able to rebuild and replenish the ranks of Loyalist Skitarii Conclaves. Otherwise, the overwhelmingly Loyalist accounts of Skitarii don't add up. I get it. In "modern" 40K, Skitarii are Loyalist. We don't have a Dark Mechanicum codex with Chaos Skitarii yet. If you see Skitarii on the tabletop, you know they are Imperium and Loyalist. That translates somehow into Horus Heresy...but if you think about it, you need to maintain consistency. Not claim "Loyalist Skitarii" are almost wiped out, with a mere handful remaining, but somehow you have plenty of them crawling out of the Imperial woodwork, ready to defend Loyalist worlds and serving Zagreus Kane's cause.
My head canon is that Zane has a secret manufactorum on Terra where he is able to replenish the ranks of his Loyalist Skitarii Conclaves, which is what occurs in Aaron Dembski-Bowden's Master of Mankind. That's why you have Skitarii in that novel, helping to fight the War in the Webway. That's the only thing that makes sense to me, and I will stand by this head canon. Oh, and that Loyalist Forge Worlds are active in helping reinforce and training new Skitarii. Perhaps this is what leads to the current status quo in 40K - so instead of Skitarii being the Fabricator General's personal army, they're now garrisoned across Forge Worlds because of the state of events when Zagreus Kane is in exile in Terra, and he has to rely on the myriad Forge Worlds to train and replenish Skitarii for him. So this continues into modern 40K, which leads to modern Forge Worlds all maintaining their own Skitarii Corps. It's a tradition that started with Zagreus Kane and the necessities of the Horus Heresy. Now everything makes sense!
