I realized I completely forgot to write a lore article on
The Devastation of Tallarn. I must have been busy when it was released back in August 2024 - that was when I was preparing to return to Singapore from Minneapolis - so I wasn't able to write, and after I returned to Singapore, my stuff took a while to return, so it completely slipped my mind once things settled down. Oh, well.
In a way, I suppose it's fine anyway, given that Journal Tactica The Battle of Tallarn Part 1 is just released, and that covers the first, opening battle of the Battle of Tallarn. The Devastation of Tallarn, released for Legions Imperialis about 2 years ago, covers the fall of Sapphire City, which is way after that first ambush the Tallarn Reborn Cohort launched upon the invading Iron Warriors armored patrol. So chronologically, covering The Devastation of Tallarn's Sapphire City arc after Part 1's first ambush is more fitting.
I will have to sum everything up because there's over 50 pages of lore in this book, and I don't think anyone wants to read every single detail. If they do, they would have bought the book, not read an online article, ha ha. In a way, my summary is to persuade you whether you should buy the book, or to help you catch up on the lore quickly, to know what's this whole Tallarn is about.
Tallarn is located on a major warp route to Terra, connecting the holy birthplace of Man to the lynchpin Loyalist stronghold of Inwit. Initially, Tallarn tried to stay neutral, neither renouncing their Loyalty to the Emperor nor rallying to the Loyalist cause in hopes that the Heresy will pass them by, like the Great Crusade.
They were wrong.
Like in the Journal Tactica, they explain here that Tallarn is one of the first worlds encountered by the Imperium in the Trailing Tempest region, and had a bloodless Compliance. At first, the Imperium decides to preserve Tallarn as the only agri-world in the region, not wanting to destroy its biosphere, so they assemble facilities in vast caverns tunneled into the rock. Basically, they create subterranean storage vaults with the capacity to stockpile immense quantities of arms and munitions, as well as serve as secure shelters.
These are concentrated in the Crescent Province in the north, with Khedive Plateau serving as muster and landing ground for the colossal military formations of the Excertus Imperialis. There's also Rachab Fortress. Within the Tallarn system, Marad has refueling stations for docking vessels or Pilgrim's Rest for fleet anchorage.
As the Great Crusade expanded, the Imperium discovers more agri-worlds, and Tallarn's significance wanes, providing a place of refuge and rest, and as a supply hub far from the frontiers of the ever-expanding borders.
Here's a brief summary.
- The Inwit Protective, the Imperial Fists' primary fiefdom, is attacked by Traitor's forces, and Rogal Dorn's orders its garrison to marshal as many troops from local systems to defend the cluster. The strike frigate, Light of Inwit, at Pilgrim's Rest, redirects vessels from the Tallarn system toward the Inwit system.
- Perturabo and the Iron Warriors appear and virus bomb Tallarn to oblivion.
- The Iron Warriors land in Tallarn's northern continent, in a region they dubbed The Northern Desolation, to find a weapon (the Black Occulus/Cursus). The surviving millions of Tallarn's populace, alongside Imperlais Auxilia regiments and vast stockpiles of armored vehicles placed there before the Horus Heresy, having sought shelter underground, reorganize and begin a guerilla war. A surviving astropath in Tallarn also sends a cry for help, summoning vengeful Loyalist forces to assist Tallarn (this is also covered in John French's Tallarn stories).
- As Loyalists - comprising of hosts of Imperialis Auxilia, battle-automata, Legionaries, Knights and Titans - reinforce Tallarn, the Iron Warriors find themselves on the back foot. Perturabo dispatches a fresh force to establish a stronghold on the surface, targeting Sapphire City, which sits atop a massive shelter network thronging with Loyalist troops, and provides a staging point within the Northern Desolation. They succeed, slaughtering millions of Imperial Army crew, and also apparently with the help of Alpha Legion operatives, who attack the Loyalists from within.
- The Loyalists launch an attack to try and take back the Sapphire City, whose subterranean shelters they now name the Sightless Warren. They fail and are massacred by the Iron Warriors. Only the Solar Auxilia from the Ithak-Nur and Sectanal Regency Guard Cohorts escape, thanks to a near-suicidal breakthrough by the White Scars Brotherhood of the Foresworn.
- The Loyalists launch a second attack on the Sightless Warren. This time, Loyalist Mechanicum deploy a colossal macrocannon from the crashed battleship Victory's Sacrament in the Kadir Plains, and the vengeful survivors of Ithak-Nur and Sectanal Regency Guard Solar Auxilia Cohorts ambush the intercepting Iron Warriors, concealing their vehicles in a tank graveyard from the previous battle to surprise them. While the Loyalists succeed in retaking Sapphire City at first, sabotage blows up four Legio Gryphonicus Titans, obliterating vast swathes of Loyalist armor and forcing them to retreat.
- Despite their consecutive losses, the Loyalists score a tiny victory when Imperial Fists sabotage a macro transporter, Eagle's Talon, and deny the Traitors Iron Warriors Inductii and tanks reinforcements, and it falls right into the battle at Arida Pass, destroying everything there. Surviving Titans continue to fight in the crater.
- The Loyalists launch a third attack on the Sightless Warren, with a flotilla attempting an orbital drop despite the Tallarn defenders protesting that it's a bad idea. Unsurprisingly, the Loyalists fail once more, and Iron Warriors reveal a colossal force of tanks freshly constructed within the Sightless Warren, with their Inductii crew directly grafted into their armored hulls. Ugh.
- The vast Golden Fleet of the Rogue Trader Sangrea translates into the Tallarn system - and this is also in John French's Tallarn stories, by the way - and blasts apart the Iron Warriors fleet after pretending to be Traitors. The detonating Traitor vessels create an aurora that the Tallarn survivors call the Inferno Tide.
- Governor-militant Dellasarius is murdered by Traitors (Alpha Legion operatives), but the defenders are galvanized further, the Loyalists rallying and mustering every available asset upon the Khedive Plateau for one final battle, strengthened with reinforcements from orbit after the Iron Warriors fleet was blown apart. Just as he was about to lose, Perturabo predictably withdraws (a common pattern we see him repeat later during the Siege of Terra), using the Warmaster's order as an excuse for the IVth Legion's defeat. Tallarn is finally back in the hands of the Loyalists, the mortals claiming an undisputable victory over transhuman Astartes.
There's a further expansion of lore after that summarized chronology, but I'm not sure I can cover all the details. Here are some interesting stuff I picked up.
The Iron Warriors, after translating into the system and settling grudges within their own ranks (because Chaos and evil), coalesce around the Iron Blood, Perturabo's flagship, and attack the orbital refineries of Marad. Then they slingshoot toward Tallarn, whose orbital defenses are neglected. However, a cadre of officers from the 71st Cinder Born Solar Auxilia Cohort, took control of Tallarn's equatorial defense station and fought back against the Iron Warriors, bringing the orbital defenses back to life and broadcasting a warning to the population below, even as the IVth Legion fleet cut the weapons platforms and void craft apart. Even the Imperial Fists strike frigate, Light of Invit was hunted down by Kasimir Garsenn, an Iron Warriors commander.
Tallarn is then virus-bombed to oblivion, the Iron Warriors using a new strain of life-eater virus modified by their Lyssatra.
Perturabo believes the Black Occulus/Cursus is a weapon of arcane power, and sequestered on the doorstep to Rogal Dorn's fief, he believes he can use it to burn a path through the Inwit Protectorate, ruining the Praetorian's homeworld and lighting the way to Terra.
With Tallarn's atmosphere toxic from the virus bombs, the Iron Warriors descend in environmentally sealed vehicles to search for the Cursus, focusing on the northern continent, especially in the area that was formerly the Crescent Province, encompassing Tallarn's shelter network around Khedive Plateau.
Commander Garsenn is put in command of the search, and for almost two months, they find nothing. Instead, they dissolve into infighting and petty rivalry as tension grows. Eight weeks after the viral bombardment, they finally pick up vox and auspex signals, and they dispatch patrol sections to investigate. Commander Garsenn's 32nd Armor Echelon heads to the Sapphire City, encoutering Aurox carriers and Aethon heavy Sentinels, which they happily butcher.
Fortunately, they pay the price for callous murder with their lives.
Leman Russ Vanquishers show up and wreck Iron Warriors Predators. Secondary squadrons of Leman Russ Executioners and Annihilators back them up, showing livery of the Tallarn Reborn, luring the Iron Warriors into a trap and destroying their Predator tanks.
The Tallarn Reborn is primarily comprised of the 71st Cinder Born Cohort, rallying all the far-flung regiments stationed upon the world and Tallarn's surviving populace to retaliate against the Iron Warriors who murdered their world. Led by Cohort-Marshal Jasira Sannoval, who had retired long ago and now takes up command, the Tallarn Reborn is formed around a core of veteran Solar Auxilia. They are trained and armed in the pattern of Solar Auxilia armored cohorts, placing a single veteran auxiliary of the Cinder Born in command of a tank crew of second line Imperial Army troopers, multiplied ten thousand-fold across each shelter to form the skeleton of new cohorts.
Reacting with transhuman swiftness, the Iron Warriors fight back, their Predators destroying Leman Russ tanks in return. As Predator and Leman Russ squadrons tear each other apart, the Tallarn Reborn attempt to counter the Kratos squadrons, with Aethon Heavy Sentinels emerging to distract them and pin them in place.
Then entire squadrons of Leman Russ Vanquishers fire, simultaneous volleys targeting individual Kratos to ensure their destruction.
The Iron warriors are forced to retreat, maimed by the ambush, and two of their patrol sections are wiped out by concealed Tarantula sentry guns. Only a single patrol section wins, its Kratos smashing directly into Tallarn Reborn Leman Russ tanks and thwarting their ambush. The remaining two patrol sections limp away, severely mauled.
At Sapphire City's outskirts, Commander Garsenn's core armor centuries are ambushed by Imperialis Auxilia tanks consisting of Valdors, Macladors, Destroyers and a single Stormblade, Ignifera, the command tank of Cohort-Marshal Jasira Sannoval. Despite his three armor centuries comprising of Land Raider and Sicaran battle tanks, Garsenn is forced to retreat, swearing as "mere" auxiliaries annihilate his massed tank squadrons. He desperately requests for help over the vox, unaware that many IVth Legion divisions have also fallen prey to similar ambushes across the Northern Desolation's dead metropolises.
Only Warsmith Strux's 18th Grand Battalion responds, his storm batteries bombarding the Sapphire City. Garsenn dies, a firestorm engulfing his surviving tanks amidst the ordnance, and the Tallarn Reborn retreat.
The first Loyalist attacks claim over a thousand Traitor tank kills in the span of two hours. Impressive. On the other hand, they also lost almost a thousand Leman Russ tanks, ouch. However, this is evidence that mere humans can beat transhuman legionaries, having killed more Iron Warriors vehicles than they had lost.
However, the Iron Warriors are far from annihilated. Within a day, they land tens of thousands of vehicles, including bonded Legio Cybernetica maniples and massed tank formations of the Selucid Thorakite Legiones Auxilia.
Despite their initial successes, the Loyalists' ambushes stall. Iron Warriors storm batteries and Thorakite siege lokhos bombard cities to deprive the Tallarn of cover, Fire Raptors strafe the sites, and Land Raiders and Spartans' AV14 being too tough for the Tallarn tanks to penetrate.
Aware that they cannot win alone and need reinforcements, the Tallarn stubbornly continue their campaign of hit-and-run, keeping the Traitors at bay from their shelters. Aware of this - and this is actually the plot of one of John French's Tallarn short stories - Marshal Lycus, the only surviving Imperial Fist from the Light of Inwit, along with a tercio of Tallarn Reborn armor dispatched from the Rachab Fortress reach a lone astropath, who was staying at a tiny civilian shelter beneath Crescent City censorium before the Iron Warriors virus-bombed Tallarn. Iron Warriors Terminators followed in hot pursuit, massacring the Tallarn Reborn soldiers and killing Lycus, but they were able to prevent the IVth Legionaries from breaching the airlock. Before they sell their lives dearly, Lycus and the Tallarn soldiers are able to instruct the astropath to send a message pleading for assistance. Fortunately, 93 days after the Iron Warriors' arrival at Tallarn, Loyalist vessels show up to reinforce them.
Funnily enough, there's a small footnote that observes how vast armor reserves, food stockpiles, large qunatities of munitions and regiments of Imperialis Auxilia have been continually shipped toward Tallarn over the years, and they suspect Horus Lupercal planned to use Tallarn to consolidate military resources and an ideal stockpile for a Traitor push into the Segmentum Solar. Having observed both the lack of conviction for both Traitor and Loyalist cause within those Imperial Auxilia forces relocated to Tallarn, Horus intended to accrue forces on the backwater world without rousing the suspicions of the Loyalist war effort.
Unfortunately, that is all undone when Perturabo stupidly obliterates Tallarn without warning, just because he seeks the Cursus, and the Imperialis Auxilia regiments garrisoned on Tallarn are now forced to fight the Traitors just to simply survive. In other words, Perturabo messed up Horus's plans with his impulsiveness, and causes the wargear and military might amassed upon Tallarn to be wielded against them instead of for the Warmaster's cause. No wonder Horus sounds so pissed when he called Perturabo and orders him to withdraw from Tallarn. He must have known the vast reserves of armor, munition and Auxiliaries on Tallarn would drown Perturabo in an unending quagmire of war that the Traitors can ill-afford to be stuck in.
Anyway, back to the Loyalist vessels. You'll notice I'm not calling them a fleet...because they aren't. Rather, these Loyalist ships pour into the system either alone or in small flotillas, approaching from countless directions. The Iron Warriors fleet is suddenly outnumbered and unable to prevent all of these ships from landing reinforcements on Tallarn's surface.
Cohort-Marshal Jasira Sannoval's Carmine ambush tercio was fighting against the Iron Warriors in the Sapphire City spaceport when the reinforcements show up, about six freeblade Knights and their accompanying talons of Armigers smashing apart Iron Warriors Predator squadrons. The Empyrean Coursers Freeblade company has saved Cohort-Marshal Sannoval's Carmine ambush tercio, and they repay the favor by attacking alongside the Knights to annihilate the IVth Legion division.
Across the Northern Desolation, Iron Warriors armor centuries are overrun by massed Loyalist tanks, and the IVth Legion are driven back to their bulk landers and fortifications. The commanders in Sapphire City light up their array of geo-locator beacons, allowing the Loyalist reinforcements to assemble but also exposing their location to the Iron Warriors. Other shelters, such as the Rachab Fortress and Cobalack Shelter, simply rely on scouting forces of armor to escort the newcomers back toward their bases, not wanting to risk exposing their locations, but having to fight off Iron Warriors tanks prowling the wastes.
Among the reinforcements was Princeps-master Yasue Koenen of Legio Gryphonicus, arriving in the mustering ground of Khedive Plateau at the head of Battlegroup Meridian. White Scars show up in the Kadir Plains east of Sapphire City. Hundreds of thousands of tanks emerge from heavy landers and assault dropships across the Northern Desolation, comprising of many Imperialis Auxilia regiments. Including the Ryuusei Katanas. The armies of the Imperium consist of auxiliaries, taghmata, Legionaries, Knights (House Yato among them!) and Titans.
Perturabo refuses to give up, still determined to claim the Cursus for himself, and decides to build a fortress to turn the war into one of siege and attrition that the Iron Warriors are so famed for. He chooses Sapphire City, intending to obliterate the massed troops who had marshaled to the city. The Iron Warriors fleet converge in a single space above the Northern Desolation to land troops, sweeping aside the fragmented Loyalist fleet, with even the battleship Victory's Sacrament under Admiral Phoroc falling to the IVth Legion ships.
The Iron Warriors begin with an orbital bombardment of Sapphire City, then deploy a vast invasion host under the command of Warsmith Cyrus Strux and his Hexad Themata, as well as Titans. In contrast, the Loyalists are divided and bickering amongst themselves, with officers from a hundred different Imperialis Auxilia regiments arguing over the course of action, while Legiones Astartes, Taghmata and Knight commanders kept to themselves. This forces Cohort-Marshal Sannoval to rely only on the Tallarn Reborn even as the Sapphire City is bombarded.
Once the orbital bombardment ceases, tercios of the veteran Sapphirine Ghosts Tallarn Reborn Cohort emerge into the devastated Sapphire City. Though annoyed by her initiative, the Imperialis Auxilia commanders dispatch their tanks to join her tercios on the surface, where they prepare to ambush the Iron Warriors, tens of thousands of tanks ranging consisting of columns of Leman Russ, Malcadors and Carnodons.
Tanks emerging from Rho-West Shelter to join the forces at Sapphire City encounter Traitor Titans from Legio Krytos, who proceed to annihilate them before destroying the shelter. A Warmaster Titan is among them.
The Sapphirine Ghosts await the Iron Warriors' attack, but instead of the IVth Legion or the Selucid Thorakite, Leman Russ Demolishers, siege Malcadors and Stormsword super-heavies of the Galibed Oathsworn show up, and they are Iron Warriors' auxiliaries as well. So they excel in siege warfare. A Galibed Oathsworn Stormsword destroy a Sapphirine Ghosts Leman Russ Annihilator, and after a pause because they wonder if there are enemy tanks laying in wait, they move on because the Sapphirine Ghosts are disciplined enough not to fire. Thankfully, this reveals secondary squadrons of Basilisk and Medusa artillery following behind.
The Sapphirine Ghosts finally strike, a Valdor tank destroyer taking out 3 Leman Russ Demolishers of nthe Galibed Oathsworn. Leman Russ Annihilators of the Sapphirine Ghosts attack the Oathsworn tanks from behind, joined by Executioners' plasma cannons that blind the Traitor crews. Vanquishers disable or destroy Leman Russ and Malcador tanks on the flanks of the Traitor Stormblade super-heavies (not Stormsword? I thought they were Stormsword super-heavies).
Long story short, the Sapphirine Ghosts wipe out the Galibed Oathsworn tanks and artillery except for the Stormswords. Siege Breaker Company Thyreos surge forward, using the bulk of their super-heavies to smash aside the Loyalist tanks. Leaving the still-intact Stormswords and thousands of wrecked enemy armor in their wake, the Sapphirine Ghosts then encounter Iron Warrior Sicaran squadrons and Contemptor Dreadnought talons, who linger behind the Galibed Oathsworn, waiting as their allies are slaughtered for the defenders to reveal their position and true extent of their numbers.
Though the Tallarn Reborn would usually retreat here, thanks to their strike and fade as phantoms doctrine, the Sapphirine Ghosts instead hold fast as the Iron Warriors fall upon them. Unfortunately, in less than thirty minutes, almost all the 100,000 Sapphirine Ghosts auxiliaries who deploy to shield the Loyalists' muster are butchered, with the few surviving tercios hunted down by Orgus attack flyers.
Fortunately, the battle-automata of Taghmata Zelth emerge from south of Sapphire City to claw apart Iron Warriors tanks and tear down Contemptor Dreadnoughts. White Scars Thunderhawk and Storm Eagle gunships drop assault legionaries with melta bombs on the Iron Warrior tanks, with dismounted Tallarn Reborn infantry making use of the central rise's altitude to avoid the toxins and virus in the atmosphere. Both of these allies allow significant pockets of Sapphirine Ghosts tercios to escape.
The Sapphirine Ghosts didn't sacrifice themselves for nothing. Tens of thousands of tanks emerge from Sapphire City, amassing in a defensive line that stretches almost 40 kilometers. South of the Sapphire River, Loyalist super-heavies ready. The Loyalists and Traitors trade artillery fire. Then the Hexad Themata invade the city in a dozen divisions, each targeting a specific point in the Loyalists' line.
Kratos heavy tanks with flanking Sicaran Punishers, Arquitor, Vindicator and Thunderstrike bombards and storm batteries, smash into the defender lines, but the Loyalists have numbers and pour more tanks into the killing fields. Warsmith Strux's armor century of seven Fellblades lead a breakthrough attack, crushing Loyalist tanks as they desperately try to stop the Iron Warriors from breaching the Omikron-North shelter.
Legio Krytos Battlegroup Sabaktes reach Sapphire City along the Crescent Sea's shoreline. Loyalist armor are forced to retreat, as do the Taghmata Zelth battle-automata, the cybernetica directed to pull back to the Sigma-North shelter. However, the Traitor Titans are ambushed by Loyalist columns of armor who blow out the void shields of the Warhound Titan, Sunderer, and the Acassian Linebreakers' Bellerophon titan-killer trident, a squadron of Shadowswords, fire from their concealed positions and destroy the Sunderer with their volcano cannons.
The Iron Warriors appear to be winning, and despite their initial success, the Acassian Linebreakers cannot hope to stand against the full might of Legio Krytos Battlegroup Sabaktes. The Warmaster Titan Typhoeus is revealed to be among them. Fortunately, the Empyrean Coursers Freeblade company saves the Cohort from destruction, striking at the titan maniples' exposed flanks after wading through the Sapphire River.
In the north of Sapphire City, White Scars Predators and Sabers destroy Selucid Thorakite armor, the Brotherhood of the Foresworn making use of their mobility. They then clash against Taghmata Suhurmasu armor who are following the Secluid Thorakite, in a series of hit-and-run until the Incaladion Taghmata close about the shelter's entrances, then the White Scars are forced into a head-on fight, their Terminators wrecking automata, and jump pack troops attacking Mechanicum forces. Unfortunately, lots of White Scars power armored Legionaries die because of the toxins, but their sacrifice bought the shelter a reprieve, the Taghmata withdrawing after suffering losses.
Cohort-Marshal Sannoval is excluded from the main defensive front as reprimand for directing the Sapphirine Ghosts to the surface alone, so she musters whatever forces would heed her directive, including the Tallarn Reborn Cohort, to prepare a counterattack in the eastern cityscape.
While hundreds of thousands of troops die to enemy fire and toxic atmosphere, the Traitor host also invade the caverns beneath Sapphire City, exploiting the breach the Legio Krytos open in the Rho-West shelter and sending Iron Warriors breacher squads along the access tunnels. Termite assault drills also dig underground alongside tunneling machines belonging to the Magos of the Belial Ordo Reductor Covenant.
While Sapphirine Ghosts and Ithak-Nur Cohorts fight in the city above, the Tallarn Reborn infantry tercios muster to repel the subterranean assault, tercios of Veletarii equipped with augury scanners.
Then there's the story from John French's Tallarn: Executioner where Alpha Legion operatives infiltrate Loyalist armor cohorts to destroy them from within. Broadcasting Loyalist indents, they are allowed to go past the Loyalist defensive lines, and they do so before shooting the Loyalist tanks in the back. Ouch.
The treachery breaks the Loyalist defensive line, and reserves of Traitor Selucid Thorakite auxilia exploit it, pushing into the Xi-East and Xi-West shelters, their massive columns destroying Loyalist armor still escaping the shelters. The Acassian Linebreakers, having escaped Legio Krytos thanks to the Empyrean Coursers freeblade company, encounter the Iron Warriors Mastodon and Spartans with massed Terminator detachments and Leviathan Dreadnoughts.
Omikron-North and Omikron-Central shelters fall to the Traitors and basically Iron Warriors breachers and Ordo Reductor cyborgs manage to breach the shelters, and though the Tallarn Reborn manage to throw back a dozen successful Traitor breakthroughs with reserves of Imperialis Auxilia troopers, the Iron Warriors are inevitably getting closer to the shelters' entrances and environmental controls.
Only Omikron-South remains firmly in Loyalist hands, with Cohort-Marshal Jasira Sannoval and her Tallarn Reborn holding strong and firmly ensuring the retreating tanks aren't Alpha Legion operatives. Realizing that Sapphire City has fallen, Sannoval decides to issue the order to withdraw. Whatever armor from Sigma-South, Pi-East and Xi-South marshal to the surface with whatever fuel they can carry, to meet up with the retreating Loyalist tanks. The surviving auxiliaries from Omikron-South shelter set out and pass through the Sapphire River, collapsing the tunnels to bury both stalwart Veletarii and assaulting Traitors. They are joined by the cybernetica of Taghmata Zelth and White Scars tanks.
After joining the mustering host from Pi-East vault and companies of battered tanks who survive the conflict, led by surviving members of the Ithak-Nur Tallarn Reborn Cohort, they flee east.
Warsmith Strux has won and seized the Sapphire City, and his Legion and Mechanicum allies set about to repairing the significant damage dealt to the shelters. However, Strux hungers for more, desiring to annihilate the fleeing survivors in order to break the Loyalists' resolve, and also to eradicate the more unpredictable and resilient White Scars and Mechanicum contingents before they become a real threat.
The Loyalists head for the Cobalack Shelter east, encountering Selucid Thorakite Lokhoi but delaying them with delayed-fuse shells to escape. The Tallarn Reborn, White Scars and Mechanicum then spot a massed armored division ahead of them, who proceed to obliterate the Selucid Thorakite armor. The Imperial Fists 26th Household has arrived to help!
Further east, the Loyalists departing Sigma-South Shelter are saved from encroaching Legio Krytos Titans from Legio Gryphonicus Battlegroup Meridian, Princeps-master Yasue Koenen leading them to intercept the Traitor Titans.
South of Sapphire River, Legio Gryphonicus Titans and Imperial Fists make a stand to save the Loyalists. Imperial Fists rapid strike batteries of Sicaran Arcus and Whirlwind Scorpius artillery, and Inwit Phalangites Legiones Auxilia annihilate the advancing Selucid Thorakite armor, while Legio Gryphonicus trade fire with Legio Krytos, leveling the terrain. The Knights of House Caesarean attempt to flank the Loyalist Titans from the Crescent Sea's coast, but encounter Iron Hands. House Cadmus lances were destroyed earlier during planetfall, so Legio Gryphonicus Battlegroup Meridian enlisted Iron Hands armor for help, their hundreds of tanks garrisoning the Rachab Fortress and now rolling out to meet the House Caesarean Knights.
Clan Brannsar isn't just any tank column, possessing macro-destruction phalanxes of Cerberus and Falchion super-heavy tanks matching even the destructive power of Acastus-class Knights. Despite the Iron Hands' graviton and neutron weaponry, their tanks are no match for House Caesaran's Knights in melee, their Kratos and Sicaran tanks cleaved apart by the Knights.
Eventually, even as Warlord Titans detonate, the Loyalists manage to retreat.
There is also a cool footnote regarding Inwit. The star cluster of Inwit is among the first to receive the astropathic cry for help, and the Imperial Fists commanders realize the Iron Warriors' assault on Tallarn is a preamble to an attack on Inwit. So they assemble 7,000 Legionaries from the 26th Household, both Veterans and Inductii, along with three cohorts of Inwit Phalangites Legiones Auxilia. Among the earliest flotillas to arrive in Tallarn, the fleet stops at Pilgrim's Rest, under the command of Seneschal Vedasto Roche, to wait while accruing scattered Loyalist vessels and embarked troops arrived at the system's fringe into a growing mass of ships.
Though they do not arrive in time to prevent the fall of Sapphire City, their role in saving the Loyalists fleeing the doomed city would help swing the war in the Loyalists' favor later.
The Iron Warriors consolidate and rebuild the shattered Sapphire City into a fortress. The surviving Loyalists make the journey back to Rachab Fortress or the Crescent and Cobalack Shelters. Also, the terrain in Tallarn apparently transforms, with patches of ground turning into muck.
Here's the state of affairs after the fall of Sapphire City. The Iron Warriors have gained their beachhead from which to sally forth. But more Loyalists flock to Tallarn. The defenders now have an objective to strike, with Sapphire City representing the beating heart of the Traitor invasion. That explains why they attack Sapphire City three bloody times...anyway, the IVth Legion realizes this will be no easy victory for them, and their search parties risk encountering hostile patrols from Loyalist redoubts across the Northern Desolation, with ever deadlier armored hosts showing up.
While this also essentially means Inwit Protectorate is spared from an Iron Warriors invasion for now, as Loyalist hosts from across the Segmentum Tempestus are drawn to Tallarn, it also means Inwit is deprived of defenders as Horus Lupercal's forces close in on them, bleeding them out slowly.
In the end, Perturabo fails to get the arcane weapon he wants, and the Inwit Protectorate remains vulnerable to the Traitors. Apparently, the Domain of the Reaper - the Death Guard and Mortarion - expands from Barbarus as they swallow entire star clusters, while Loyalist holdings around Deliverance retract as Traitors and renegade hosts surge.
That's it for the story in The Devastation of Tallarn. As we know, the Iron Warriors are finally defeated and forced to leave, Perturabo ordered by the Warmaster to withdraw while his forces are being massacred in the surface by resurgent Loyalist armor in one final battle. But for now, the Iron Warriors have won and taken their prize, something that will not be dislodged from their iron grip despite the Loyalists desperately attacking it three times.
