- "Our conquest is inevitable, our ascension a matter of time. Let none who are wise deny our destiny."
The Third Sphere Expansion was a series of campaigns unleashed by the Tau in the Eastern Fringe to continue the military expansion of the Tau Empire and spread the Greater Good across the galaxy. It began in 997.M41 in the wake of the Great War of Confederation against the Orks and was led by Commander Shadowsun. It ground to a halt not long after, due to the difficulties encountered in crossing the region known as the Damocles Gulf following the disastrous Second Agrellan Campaign of 999.M41 and increased resistance from the Imperium of Man, which had led to the assassination of the Ethereal Supreme Aun'Va.
The growth of the Tau Empire can be charted in three distinct stages. Called the First, Second and Third Sphere Expansions, each of these vast outward surges has seen massive military forces and wave upon wave of Tau colonists set out into the stars. Each has seized new worlds and assimilated new races for the Greater Good. In their earliest days, the Tau almost tore themselves apart as their technological innovation far outstripped their cultural development. It was only the coming of the Ethereals that rescued them from this dark period. These mysterious newcomers united the entire race, directing their efforts in a surge of incredible advancement and mutual benefit that culminated in the First Sphere Expansion. This was a heady time for the Tau, who stepped from their caves out into the stars with breathtaking speed. Losses were high among early colonists who pushed the boundaries of the possible with every new leap they took. Hostile flora and fauna as well as catastrophic accidents claimed many lives, but under the protection of the mighty Fire Caste the Tau established one colony after another. As they stretched outwards, they discovered that their homeworld, T'au, lay amid a dense cluster of viable exoplanets, and one by one, frontier colonies became settled and worlds civilised. As each star system blossomed, it was designated a Sept and named after its prime, or Sept World, each a teeming hub of culture and military strength that formed the heart of a whole settled system.
The millennia-long First Sphere Expansion saw the Tau assimilate their first alien cultures, the Ethereals guiding the absorption of the Thraxians, the Nicassar, the Kroot and many others. It also saw their first conflicts with the omnipresent menace of the Orks, a foe with whom no reasoned diplomacy could ever succeed. Soon enough, the Tau learned to hate the Greenskins for their mindless savagery, and resolved to avoid or destroy on sight every Ork they found.
By the end of the First Sphere Expansion, the Tau had secured eight glorious Septs, but this was a fraction of what the Second Sphere Expansion would achieve. From the Empire's spiritual home of T'au, the orders of the Ethereal High Council raced out along relays to its furthest comers, pushing always for greater advancements, new innovations and mightier weapons. With the invention of the ZFR Horizon Accelerator Engine that allowed Tau starships to achieve relativistic velocities in realspace close to that of the speed of light, the Tau fleets were able to push much further into space, and with a military force more impressive than any seen before in Tau history, the Fire Caste seemed ready to face whatever threats the distant stars held in store. Neither Ork WAAAGH! nor Tyranid splinter fleet could arrest the impetus of the Second Sphere Expansion, and it was not until the Tau crossed the treacherous Damocles Gulf that they encountered a foe that stopped their advance in its tracks.
The Damocles Gulf Crusade
Beyond the Damocles Gulf, the Tau encountered the Imperium of Man. Initially the Tau Empire annexed dozens of worlds on the ragged edge of the Emperor's realm, not realising the scale of the threat they faced. The Imperium's sledgehammer response came in the form of the Damocles Gulf Crusade in 742-745.M41 according to the Imperial Calendar. The Tau had never faced military strength in such concentrations, or wielded with such uncompromising belligerence, and their holdings beyond the Damocles Gulf were swiftly crushed. Worse, the Imperial forces used strange, reality-splitting space engines, the Warp-Drive, to pursue their quarry as they retreated back to the frontiers of the Tau Empire. The Imperial armies fell upon the Sept World of Dal'yth, and were only driven back at great and terrible cost. The Tau were shaken by the shock of defeat, and the Ethereal High Council knew that, should their people's confidence not be swiftly restored, cracks would form in their carefully-orchestrated beliefs. Rather than let this come to pass, the council placed the legendary Commander Farsight at the head of a mighty coalition fleet and sent him back across the Damocles Gulf to reclaim those colony worlds that had been lost. The tale of his initial successes, and of his subsequent mysterious disappearance, has been officially expunged from Tau history, yet its marks remain to this day. Regardless of his eventual fate, O'Shovah had served his purpose. In recapturing the worlds lost to the Imperium, he restored the confidence of the Tau in their destiny.
The Great War of Confederation
Throughout the Tau Empire, recently-built colony fleets were filling up orbital docks in anticipation of the call to launch a new Sphere of Expansion. Even as preparations were underway, warning signals ﬂashed across the Tau Empire's relay lines in 975.M41. An age-old foe had returned in numbers beyond imagination; the Orks were back.
They came from beyond the shroud of the Western Veil Nebula, the ragtag Ork armada emerging from the swirling gas clouds as suddenly as if they had materialised out of nowhere. As the first scans were picked up, the Earth Caste technicians believed their sensors were malfunctioning, for the size of the Greenskin fleet was staggering. The Ork invasion was composed of some dozen separate WAAAGH!s, each with a Warboss vying for overall supremacy. Only the decrepit state of the Orks' spacecraft and their incessant in-fighting allowed the Tau Empire time to react. Whilst many of the Tau panicked over the immensity of the looming threat, there was one who saw that, as always, if the Empire worked together, they could defeat even an invasion of this magnitude.
Aun'Va -- now Ethereal Supreme -- remained as calm as still water. He gathered the leaders of every Sept in order to form a comprehensive plan of action. Those Septs closest to the Ork threat -- Vior'la, Sa'cea, and Tau'n -- would combine forces in a delaying attack. Behind them, all other Septs would rush troops and starships towards the front to serve as the next wave of counterattacks. Across the Empire, the Air Caste scrambled their fleets converting trade ships and colony transports into troop carriers to accommodate the forces needed to stem the green tide. As the united Tau advanced to confront the oncoming Orks, initial engagements took place along the outermost regions of the Empire. The Tau Navy launched hit-and-run attacks to lure pursuing Ork ships within range of orbital defence stations. The combined firepower of fleet and orbital bases caused heavy Ork losses, although several stations were destroyed when Ork sabotage ships crashed into the vast structures, allowing numerous Greenskins to disembark and wreak havoc. Fire Warrior defenders were soon deployed aboard the remaining orbital stations and many desperate battles in the depths of space ensued, some lasting for many Terran months.
As the individual klanz of the Greenskins separated to follow their own pursuits, the fighting spread across space and over more than a dozen surface locations. Wherever Orks made planetfall, additional Tau ground forces were landed to reinforce the area, even on barren moons, for the aliens had to be denied any chance to scavenge supplies or set permanent roots within the territory of the Tau Empire. With the threat of being overrun forestalled, Aun'Va deemed the time was right for the next step of his master plan. Terran centuries before, when the Ethereal High Council knew that Commander Puretide, the greatest living Tau military strategist, was rapidly degenerating and would soon die, contingency plans were put into motion. The Earth Caste had long been preserving Puretide's memories -- seeking to build a sentient, artificially intelligent holograph that would look, act and most importantly, think like him.
At the time, however, there was no assurance that this would successfully replace the indispensable instructor. So, as a safeguard, it was ordained that several of Puretide's top students would be placed in stasis -- a time-proofing process that was then newly devised by the Earth Caste. This meant that, in future times of war or expansion, the Empire could still call upon masters of the art of war. Now, with the largest Ork invasion ever seen already within their borders, Aun'Va determined that a leader of great destiny was needed.
One of those cryogenically frozen was a recently promoted Tau Commander by the name of O'Shaserra, Commander Shadowsun. Of her generation of Fire Warriors, there was only a single rival who could match O'Shaserra's boldness and tactical abilities. That other warrior, O'Shovah, was not frozen, but rather chosen for glory, leading the Tau's expeditionary force to reclaim their colonies after the war with the Imperium. By the time O'Shaserra had completed her reindoctrination, the fighting had been going on for half a dozen years; the massive Ork invasion was now spread across the borders of many Septs. With their superior weaponry and the cohesion of their forces, the numerically inferior armies of the Tau had been able to check the disorderly Ork hordes. It was a stalemate, as the disparate Greenskins could not gain the momentum or unity to drive towards a Sept World, and the Tau could not eradicate the aliens from their realm. Taking leadership over a Hunter Cadre, Commander O'Shaserra joined the fray. After a daring string of victories, she earned control of a command -- a formation of many cadres. By the time Sa'cea Prime's largest moon, Vay'harra, was proclaimed clear of Orks, Commander O'Shaserra's name was already becoming well known. From there, she led major victories on the dawn worlds of Kormusan, and finally on the K'resh Expansions. With each triumph, more Tau forces were freed to apply additional pressure to the fractionalised Greenskin forces. After the total massacres of the K'resh Expansions, the power of the Orks was broken. The Great War of Confederation, as it came to be known, lasted a dozen years and firmly established a new hero in the hearts and minds of the Tau. O'Shaserra, now called Commander Shadowsun, had proven herself to a new generation -- her tactical manoeuvres at every level of command were executed flawlessly and she was not without personal heroics. Her penchant for infiltrating battlefields and launching deadly ambushes was already legendary. A bright new future for the Tau lay ahead.
The Third Sphere Expansion Begins
With the Ork invasion defeated and a new hero risen to lead the Fire Caste, Aun'Va knew the time was ripe to declare the Third Sphere Expansion in 997.M41 as the Imperials reckoned time. With more established Septs to draw resources from, this drive to expand the size of their realm was undertaken on a scale never before attempted by the Tau Empire.
As bold and dynamic as the previous Spheres of Expansion had been, they had been confined to the dense star clusters that surrounded the planet T'au. The scope of such expansions was limited -- the Tau did not have the population needed to spread further, and they had not yet fully learned to harness the full power of alien auxiliaries to aid their cause. Technical constraints proved a barrier as well, for the Earth Caste have constantly been seeking ways to develop starcraft with faster engines to allow them to bridge the vast gulf of empty interstellar space between star systems.
Aun'Va knew that now was the time for the Tau to seize their destiny. The Great War of Confederation had served to put the Tau on a total war setting -- as the Ethereals pressed each caste for greater production and higher efficiency. The Ork invasion had proven a harsh training ground for the Fire Caste, but they had now replaced the casualties of the long, drawn-out campaign. Furthermore, many Fire Warriors and their Commanders had gained invaluable experience. They were now better trained than ever to coordinate their efforts with other Septs and with the Tau Navy. The amount of alien auxiliaries at hand for deployment to the Fire Caste was greatly increased, especially the availability of the Kroot.
In order to reach those more distant systems earmarked as desirable by advanced scouts, the vast armadas of Tau starcraft had been outfitted with the latest Earth Caste modifications. The ships' propulsion systems were upgraded so that when magnified by Impulse Reactors, the new ZFR Horizon Accelerator Engines could obtain faster speeds -- propelling Tau starcraft forwards at hitherto unthinkable velocities just shy of the speed of light itself. To further lessen the burden on those space-faring craft with the longest journeys, the Earth Caste had outfitted transport craft with large stasis chambers -- allowing Hunter Cadres or whole commands to shift to far distant battle zones Terran months or years away without actually aging a day in the process.
While all Septs sent ﬂeets to aid in the great expansion, the largest gathering of force was at the northern and western extremes of the Tau Empire. There, massed at the ports and orbital docks of Dal'yth, Sa'cea, and Vior'la, were huge flotillas. In addition to the fighting classes of starships, the Tau Navy also provided whole armadas of transports to carry armies, colonists, pre-fabricated domes, Tau Drone builders and all manner of equipment. This massive force was to be led personally by Commander Shadowsun -- the newly appointed highest-ranking Fire Caste officer. Their course was to cross the Damocles Gulf, travelling past the Gri-lok asteroid fields. Target destinations had been meticulously planned out -- all planets and moons desired for colonisation were well-marked on the fleet's holomaps. Those worlds that had indigenous populations had already had many preemptive visits by Water Caste traders and ambassadors in order to explore possibilities for a peaceful annexation.
Some of the planets branded for absorption into the Tau Empire were worlds that belonged to the Imperium of Man. In these cases, Aun'Va's timing of the Third Sphere Expansion could not have been better. Water Caste agents and Gue'vesa -- human helpers who had sworn loyalty to the Tau and the Greater Good -- confirmed what the Earth Caste had already reported via intercepted Vox transmissions: due to wars elsewhere, the number of Imperial defenders at the borders of their territory was much reduced.
Some Imperial planets, those open to bribery or idealists that wished to escape the pressing yoke of servitude to an overbearing tyrant, lay down their arms at their first opportunity -- welcoming Water Caste ambassadors with pledges of cooperation. Most human worlds, however, rejected Tau overtures -- mistrusting all aliens or perhaps simply more frightened of the repercussions they would suffer at the hands of their own race. For those frontier worlds that resisted, Shadowsun and her armies swept down in a series of precision strikes. The human Planetary Defence Forces proved insufficient to even slow the Tau down, much less them hold off.
The northernmost sector past the Damocles Gulf was soon wholly in Tau hands, while to the galactic west, the sectors adjoining the Red Sun Systems were cleared of Hrud, Orks and rebel humans. Fleets of Water Caste Indigenous Inhabitants Liaison conclaves were deployed to begin their long integration process for those aliens that wished to seize upon the enlightenment that was being offered. The Earth Caste, eager to exploit their new domains, was already dropping producer domes upon recently-seized planets rich with resources. In order to keep the drive going outwards, the Tau needed to establish fuel sources closer to the front lines of expansion. Linked back to the Tau Empire by long chains of relay comms, the expansion had already claimed dozens of new worlds -- yet this was only the start.
Buoyed by her initial successes, Shadowsun rapidly led her armies deeper into Imperial territory. She seemed to be everywhere at once, driving her forces onwards. At the forefront of the offensive, the Fire Caste spearhead were already en route to their next targets before the consolidation forces that followed hard on their heels had fully landed on the newly conquered planet. Here, Shadowsun was using the old Puretide maxim: "Follow up a victory by striking quickly, and you will win another."
As Shadowsun passed into the Imperium's interior she encountered ever greater resistance, and she saw that to overextend her forces would deplete the momentum of the attack. Instead of crashing headlong into well-defended planets, she split her fleets, scattering them to a dozen headings. Each began a devastating series of hit-and-run attacks against which the Imperium could mount no effective counter. At length, the Imperium settled into a static defence of a handful of their most key worlds. Shadowsun exploited this strategy too, for it allowed her to again marshal her forces together and launch a massive attack on the planet of her choosing. Her first target was the Hive World of Agrellan, a gateway planet to the Dovar System whose orbit safeguarded a rich cluster of Imperial planets called the Gilded Worlds.
Transports of fresh Fire Caste warriors and many of the newest Tau weapon prototypes were rushed to this battlefront for what would surely be a pivotal conflict. Aun'Va himself came to inspire the Fire Caste, and upon seeing him, the Tau knew their victory was assured. At last, the largest class of Tau Battlesuit was unleashed, and under Shadowsun's inspired leadership, its use proved a resounding success; everywhere one strode, victory followed. Fittingly, it was this new XV104 Riptide Battlesuit that delivered the killing blow during the final engagement -- laying waste to the massive Imperial heavy tanks that had so long blocked the gates to the world's capital hive city. Although the Imperial defenders fought with their usual fatalistic grit, it was not long before the hive corridors ran with blood and only a few isolated pockets of resistance remained. The planet of Agrellan, renamed Mu'gulath Bay by the Tau after it was integrated as a new Sept World, belonged to the Tau after only a single solar day of combat and soon the whole star system would follow. As such, among the other worlds added to the Tau Empire during the Third Sphere Expansion, three full new Septs were created: Ksi'm'yen, Fi'rios, and Mu'gulath Bay itself.
The anticipated counterattack from the Imperium fell upon the Zeist Sector during the Zeist Campaign of 999.M41, and this too was part of Shadowsun's plan. As a diversion, this far-ﬂung region was sacrificed for the Greater Good of the Third Sphere Expansion. While many seeded Tau colonies fell to the elite forces of Mankind -- their vaunted Space Marines -- the eﬀort tied down the majority of the Imperium's rapid strike forces and allowed the main Tau assaults to scythe deeply into more desirable neighbouring star systems. The worlds of the Imperium toppled one after another before the precision onslaught. By the time the Zeist Campaign ended, the Tau's Third Sphere Expansion had already enlarged the Tau Empire by 133% of its prior size. The Tau showed no sign of stopping their aggressive expansion in the Eastern Fringes despite their losses in the Zeist Campaign.
Yet the commanders of the Imperial armies were infuriated that Agrellan had been taken at all, let alone in so short a time. After regrouping, the various dignitaries assigned to reclaim the lost Imperial worlds held a council of war. They agreed to stage purposefully slow retreat towards the Feudal World of Voltoris, drawing Shadowsun's fleet after them into an area where she would be badly outmatched.
The Imperium laid a deadly ambush, using Voltoris' most defensible area -- the fortress of Furion Peak -- as its anchor. The Tau, so sure of their orbital recon scans, vastly underestimated their foes. Within the forests and gulleys of that proud mountain were Colonel "Iron Hand" Straken's Catachan Jungle Fighters, Shadow Captain Kayvaan Shrike's Raven Guard, and Kor'sarro Khan's White Scars, all hidden from sight by the psychic mists of the Stormseer Sudabeh.
When Shadowsun's army made planetfall at the foot of Furion Peak, the jaws of the Imperial trap closed. Being psychically inert, the Tau were baffled by the storm-magics of the White Scars Astartes, who then led the charge to engage their foes at close range. Power Fists, Chainswords and even Combat Knives took a heavy toll upon the beleaguered Tau. Shadowsun hunted down and slew Stormseer Sudabeh, causing his mist-spell to dissipate, but by then the gates of Furion Peak had yawned wide. Scores of Imperial Knights sallied forth, cannons blasting the Tau army until the forest road was a churned mess of craters. Many of Shadowsun's most trusted teams had to give their lives to secure her escape. She swore to honour their sacrifice by redoubling her efforts in the expansion of the Third Sphere.
The Prefectia Campaign
Directly in the sights of Shadowsun's new offensive was the Dovar System. Around the star Dovaris orbited the four Gilded Worlds, a system impossibly rich in precious metals. Yet mountains of platinum and gold are as meaningless to the Greater Good as notions of individual wealth. The only resources precious to the Tau are those that can be turned to their empire's expansion -- such as energy sources that can drive the ever-evolving technology of their growing fleets.
The Fortress World of Prefectia near the Dovar System was not only an ideal staging post from which to engineer the collapse of the entire Dovar System, it was also an untapped reservoir of geomagnetic energy. The Imperium, in its typically myopic way, had fashioned the world into a planet-sized fortress, for it stood between the xenos-haunted reaches of the Eastern Fringe and the Gilded Worlds. In their ignorance, they had harnessed but a fraction of Prefectia's potential and exhausted the planet's garrison the better to wage war upon Agrellan and Voltoris. This was a fact that offended and appalled the Earth Caste scientists who studied it; properly terraformed, Prefectia would become a dynamo that would boost the Tau's conquest of the entire Segmentum Ultima into overdrive.
So it was that Shadowsun's expeditionary force turned its attention to Prefectia, the united castes bringing ruin to the planet's bastion networks and munitions hives just as they had to Agrellan. The Imperial commanders, in many ways glad the Tau had pressed no further towards Dovaris, sent in their legions for a new phase of war. It was a battle that would ultimately go the Tau's way, and the Prefectia Campaign of 999.M41 represented yet another defeat in the face of the growing power of the technologically-advanced xenos.
The Tau overcame what remained of the Imperium's defences, and had just begun to set up their own installations when the Imperium struck again. Elements of several Space Marine Chapters, foremost amongst them the Raven Guard and White Scars, executed a series of simultaneous planetstrikes, initiating a seek-and-destroy mission to swiftly eliminate the Tau forces' leadership. Kor'sarro Khan, Captain of the White Scars 3rd Company, personally vowed to decapitate Commander Shadowsun, for she had first outmatched him on Agrellan and then escaped his blade again on Voltoris.
Using herself as bait, Commander Shadowsun took advantage of the Imperium's fixation on slaying her in order to spring a masterful trap. Many casualties were inflicted upon the Space Marines, including the Raven Guard Chapter Master, Corvin Severax, who was slain by Shadowsun herself, to be replaced by his subordinate Shadow Captain Kayvaan Shrike. Not even a large contingent of Imperial Knights from House Terryn of Voltoris could turn aside the devastating Tau counterattacks. Only through heroic actions were any Imperial forces able to retreat off-planet. Their foe defeated, the Tau believed their expansion into the Dovar System and beyond could now continue unopposed while the Imperium nursed their wounds. In this prediction, the Tau ultimately proved to be profoundly mistaken.
On Prefectia it was the deployment of the KV128 Stormsurge Ballistic Suit, the first in a new generation of Tau super-heavy war assets that served as mobile artillery, that proved to be the turning point. Besting the forces of both the Raven Guard and White Scars Astartes as well as the Imperial Knights of House Terryn, Commander Shadowsun had claimed what the Tau believed to be their greatest victory yet.
With the fighting withdrawal of the Space Marines and the evacuation of House Terryn's assets, the remainder of the Imperial forces upon Prefectia soon followed suit. Shadowsun, her forces already enveloping the last centres of resistance, had secured her dominance beyond doubt. The expansion of the Third Sphere would continue apace. The deployment of the Stormsurge KV128 Ballistic Suit was by no means limited to the battle on the edge of Goliath's Eye. In every Tau theatre of war, the looming artillery walkers emerged.
Some of their number, in a practice pioneered by Commander Sternshield, were used as the centrepieces of a variant Kauyon where the lure was not only the bait to draw in the enemy army, but the tidal wave that broke it against the unyielding cliff of the wider Tau force. Others formed roving gun emplacements that added daunting firepower to the Tidewall Rampart gun clusters. They strengthened the Tau's stranglehold upon Prefectia day by day, blasting apart the remnants of Imperial occupation, pulverising the gun-gargoyles encrusting each dormant hive and toppling the statues of the planet's former owners from every plinth. In a matter of Terran months, the Fortress World had fallen completely to its Fire caste conquerors, just like Agrellan before it. To great celebration, Prefectia entered the Tau Empire as the Tau Sept of Vas'talos, which means "boundless scope" in the Tau Lexicon.
Soon enough, plans were being made for the next stage of the Third Sphere Expansion. Many of the shas'ar'tol believed the consolidation of their gains to be the next step, the better to build the foundation from which they would strike further into Imperial space. Aun'Va overruled the Fire Caste council in person, the wisdom of his speech so obvious his commanders felt foolish they had not reached the same conclusion themselves. The Tau expeditionary force would divide its strength, one half pushing further into the Dovar System whilst the other returned to ensure the supply route to Mu'gulath Bay remained intact.
Across every Sept World, colony and orbital station, Prefectia was already being portrayed as the Tau's greatest victory yet. Already plaudits were being given and speeches being made, the Water Caste extolling far and wide this latest glorious manifestation of the Tau's destiny. Much mention was made of Commander Shadowsun, her image broadcast across unnumbered holoscreens on a daily basis. The grand Kauyon she had staged upon Prefectia was hailed as a work of genius. She had slowly escalated the engagements against the Imperium's shock troops, many true believers in the Tau'va giving their lives in battle to goad the enemy further and further until they attacked in force, then trumping them with the true strength she had concealed all along. In this manner the Supreme Commander of the Fire Caste had personally slain what the Tau believed to be the grand monarch of the Space Marines, a grim-faced figure in black armour who had long directed the Imperial war effort, but had only now been lured into the open by Shadowsun's masterful Kauyon strategies. With the death of their greatest leader, the Water Caste excitedly reported, the armies of the Imperium would be cast into disarray, caught in a power vacuum which it would take them many of their years to escape.
Featured prominently on every holoscreen from one end of the Tau Empire to the other were the Ghostkeel Battlesuits and Stormsurge Ballistic Suits that had given the Fire Caste the edge they needed to defeat the warmongering brutes of Humanity. At the end of every triumphant broadcast, serene images of the Ethereal Caste would dominate the screen, telling the Tau that every life lost in the furtherance of the Greater Good was a life well-spent, and that no true follower of the Tau'va could believe otherwise.
These broadcasts were kept on loop for many Terran days, not purely for the sharing of information, the betterment of unity and the raising of morale, but also because the Ethereals knew well that conviction was amongst the Tau's strongest weapons. The battle for Prefectia was won, they said, but the war against the corrupt and bloated empire of Mankind was only now beginning. They had little idea how right they were.
The sheer scale and ambition of the war for the Eastern Fringe was becoming one of the wonders of the Tau Empire, feted loud and clear by every one of its citizens. News of the morbid, brutish race they had outwitted and outfought spread far and wide. Every new clutch of Tau youngsters was told stories of greedy, rotten humans that sought to smother the stars, suffocating all light and hope without ever knowing why.
The news of the Great Victory was also broadcast to those civilisations that had allied themselves with the Tau Empire, and even many who had not. There were those amongst them who realised that under the triumphalist claims was buried a death toll that likely spiralled into the billions. Some of their number, those who had come to truly understand the Imperium of Man, realised that the grandiose war the Water Caste spoke of had every chance of drowning the Tau Empire in an unremitting tide of death. The news soon reached a chain of star systems coreward of the Damocles Gulf, long abandoned by the Tau Empire. There, a legendary leader, Commander Farsight, gathered his people and made ready for a war that would change the history of the Tau forever.
Upon Prefectia, the Tau Empire had proven itself a force to be reckoned with. On a strategic level, their warsmithing was impressive, and their carefully prepared traps had lent them a tactical advantage time after time. The greater battle, however, was yet to be won -- not only for the worlds surrounding the Damocles Gulf, but for the Tau's place in the galaxy.
The Imperium had lost Prefectia to Aun'Va's expeditionary force, expertly commanded by the military genius of O'Shaserra. Ultimately, though, the Imperium considered that world of little strategic value. There were more vital targets in the Eastern Fringe, targets to which warfleets had already been despatched via the fickle tides of the Warp. Countless regiments of Astra Militarum, Orders of Adepta Sororitas, and macro-level war cohorts from the Adeptus Mechanicus were inbound, slowly but unstoppably, to the greater war zone. According to the assessments of Imperial strategos and war savants, there was no way the Tau could conquer the Gilded Worlds without either abandoning the surrounding star systems or leaving their own heartlands poorly defended. Both were courses of action they believed the Tau would never take.
As for the battlegroup assigned to the reclamation of the worlds recently taken, they too had greater plans reaching fruition. With the focus of the Fire Caste High Command upon Prefectia, the Imperium turned its eyes once more towards Agrellan, renamed Mu'gulath Bay by its presumptuous Tau conquerors. Though the twelve great hives of that world had been brought low by Shadowsun's masterful offensive, and though the planet's rad storms and toxic atmosphere made it all but inimical to new life, the location of the planet made it valuable indeed. More than that, it had become a symbol for the Tau Empire -- a symbol of triumph over Humanity that the Imperium could not abide.
The Imperium spans a million worlds, and with every cycle Holy Terra describes around Great Sol, dozens are lost and dozens more settled in the Emperor's name. Yet rarely does a Chapter Master of the Adeptus Astartes die in battle, and rarer still one of the First Founding, those whose predecessors fought at the side of the legendary Primarchs. Such fallen heroes are not to be forgotten, but to be avenged. Through the inky void the Space Marines and their allies headed for Agrellan once more, intent on striking the Tau defenders there whilst the pride of the Fire Caste was consolidating its gains in a different star system. The slight upon the honour of the Adeptus Astartes would be repaid a hundredfold.
There was revenge to be wrought, and in such matters, the Imperium is expert indeed.
Second Agrellan Campaign
Following the great victory upon Prefectia, Ethereal Supreme Aun'Va gave an impassioned speech. It was an awe-inspiring sight, the Ethereal hovering over the crater-ridden battlefield, the burnt-out frame of a fallen Imperial Knight as his backdrop. It was a broadcast viewed by every member of the Tau race, even those too young to walk.
In his victory speech, Aun'Va announced another Tau triumph. He praised the leadership of Commander Shadowsun, and acknowledged the mastery of the Fire Caste. The Ethereal Supreme spoke of how the Tau race stood now on the precipice of greatness. Before them lay endless possibilities -- they had but to seize them. Once, the Damocles Gulf had thwarted their expansion, as had the rule of the Imperium of Mankind. The Tau had now overcome these obstacles to stand once again victorious.
Aun'Va announced that the Third Sphere Expansion was only just beginning, and called upon each Sept World by name to give more of themselves to the Greater Good. Just as the frontline soldiers of the Fire Caste were asked to give everything in defence of the Tau'va, so too must each citizen of the Tau Empire; production must double, new technology must be developed and every part of society must be made more efficient.
It was a staggering statement, for the Tau Empire was already on a war footing -- production was running at maximum capacity simply to supply the enormous amounts of materiel needed to fund the Third Sphere Expansion. Yet Aun'Va was asking for more. To this request, the Tau responded with earnest devotion. If the great leader of their people asked, it would be done. There would be no questions and no qualms about the cost, only ardent efforts to increase production by any means necessary.
With the foe gone from Prefectia, Aun'Va began to plan the next phase of the expansion. Half of the Fire Caste forces on Prefectia were sent to aid in the exploitation of the Dovar System -- suppressing or eradicating native populations, protecting Earth Caste installations and safeguarding Water Caste diplomatic actions. The remaining forces were to return to Mu'gulath Bay. There, they could briefly refit and train while the war council laid plans for the next wave of planetary invasions. It was generally accepted that the Imperial hold upon the region had been broken, and it would be a long time before their forces returned in great numbers. The lmperium had suffered a series of losses that would have set the Tau Empire back generations, including the latest blow -- losing the "King" of the Space Marines. It would take them some time to recover from such shattering setbacks. In their understanding of the Imperium and its ways, the Tau could not have been more wrong.
Even before Agrellan was attacked, the aggressive infiltration of the Tau Water caste had been marked. Astropathic choirs broadcast warnings and armies were already mobilised before the Tau's lightning fast invasion was complete. The Tau success only increased the magnitude of the Imperial response. That many of the region's lesser holdings had previously given into Tau bribes and manipulations had only increased the Imperium's desire for retribution. Perhaps the only thing the Imperium was less tolerant of than xenos invasion was the betrayal or corruption of its own. The seditious, those who would lure Mankind to their doom, were loathed above all.
Forces were mustered, congregating in numbers beyond the scope of what the Tau believed possible. The vast armadas and armies of the Imperium were slow to gather momentum and had to span distances the Tau could not fathom, but once Task Force Retribution was finally launched into the Warp, there was no stopping its single-minded mission to reclaim the territory once ruled in the Emperor's name. The warriors of the Astra Militarum would not halt until they had raised the glorious banner of the Imperial Aquila where it rightfully belonged. And so, when the task force emerged from the Warp with klaxons blaring, it was as close to Agrellan's orbit as they dared, to maximise the advantage of surprise.
Soon all wrongs would be revenged a hundredfold.
The Second Agrellan Campaign, as Imperial savants would later name it, began well for the Imperium. Task Force Retribution's naval contingent was led by Lord Admiral Hawke while its Astra Militarum elements were commanded by the Cadian Lord General Troskzer from space. With the aid of the Raven Guard, the Imperial Navy successfully claimed the space above Mu'gulath Bay from the Tau orbital stations and fleet. The ground invasion was then led by the forces of the Imperial Guard, the Skitarii Legions and the Legio Cybernetica, screened by elements of the Raven Guard commanded by Kayvaan Shrike and the White Scars again led by Kor'sarro Khan. Troskzer and Shrike deployed their forces at three primary locations on the planet. These three fronts, the central, eastern, and western spearheads, would converge at the largest Tau installation located at the old capital hive city, Agrellan Prime. The ground invasion went well, and though Commander Shadowsun sprung yet another of her traps, the assault proved clumsy and hastily assembled, and it became apparent that the Imperial forces would weather the assault.
Then the skies turned red. For Commander Farsight and the forces of the Farsight Enclaves had come to aid their estranged brethren.
Shocking all sides, O'Shovah himself appeared on the field, followed by his command team The Eight. They lead a great Mont'ka assault on the Imperials. The Imperial commanders realised that with the arrival of the Tau reinforcements, victory had been snatched from their grasp and the world could not be reclaimed. They ordered a withdrawal in force, moving to Blackfossil Ridge amid a heavy supporting bombardment. They were joined by the Space Marines, who were evacuated from the field by Thunderhawk gunships save for the White Scars contingent under Kor'sarro Khan, determined to claim the head of Commander Shadowsun as they had sworn.
The tide seemed to turn again when an Officio Assassinorum Execution Force appeared on the battlefield, determined to slay the Tau's most important leaders. As chaos erupted among the Tau forces with the Assassins' attacks, Shadowsun managed to rally the Tau and withstand multiple reinvigorated Imperial assaults. However, while in her mobile command post, Shadowsun was suddenly assaulted by a Callidus Assassin disguised as the Ethereal Aun'Kar. Shadowsun was wounded, but with the aid of a force of Pathfinder bodyguards managed to take down the shapeshifting Imperial operative. But other members of the Tau Empire's critical leadership were not as lucky. The Ethereal Supreme Aun'va, trapped on Mu'gulath Bay at the time of the unexpected Imperial invasion in the wake of his speech heralding the great victory on Prefectia, was attacked by a sinister Culexus Assassin in his hidden bunker in the ruins of the hive city of Agrellan Prime. The Culexus psychically overwhelmed all of Aun'va's bodyguards before successfully hunting down and slaying the Supreme Leader of the Tau Empire.
Task Force Retribution had been intended to scour the xenos race known as the Tau from Agrellan, as those who had dared to confront the Imperium must learn of the consequences. That mission had been deemed a failure, and other elements within the task force now took precedence, and the evacuations of the Astra Militarum forces began.
The Space Marines that escaped Farsight's ambush had fought their way to evacuation points and returned to their orbiting spacecraft. They were in the process of rearming and coordinating their redeployment when they heard. A new Lord General had replaced Lord Troskzer, and his first act had been to issue an order calling for the Astra Militarum's immediate withdrawal from Agrellan. All Chapters looked to Kayvaan Shrike, for the Adeptus Astartes were under no authority but their own, and they wished to see what their highest ranking officer would do. Shrike announced that the Raven Guard would depart within the solar hour. So the Adeptus Astartes quickly embarked for other destinations, as there were more distress calls than Imperial forces to answer. Theirs was the way of war, and the concerns of one campaign or planet mattered little to them. Kor'sarro Khan, however, was enraged.
Once again the Khan was denied, once again he had failed to bring back the head of Commander Shadowsun. He was stubborn-minded enough to disregard what others were doing and continue with his own dwindling company of White Scars, but an additional command came. This one originated from the White Scars Chapter Master Jubal Khan. The remnants of the 3rd Company and its support were needed urgently back at Chogoris -- there could be no delays. The Khan was needed to help fight the Traitor Marines of the Red Corsairs.
Either not content with their triumph, or not wholly convinced of their foe's retreat, the Tau Empire counterattacked the retreating Astra Militarum and Adeptus Mechanicus forces as they made their way towards designated pick-up points across the planet's surface, often and without mercy. Ambushes slowed the Imperial forces or drained off their strength in hopeless pursuit. Yet worst of all were the air strikes. Imperial atmospheric flyers were concentrated around the landing zones, leaving the retreating masses on the ground open to the Tau Air Caste's endless strafing attacks and bombing runs. Beaten, bedraggled and showing the signs of early-stage rad-sickness, the foot soldiers of the Astra Militarum dragged themselves onwards beneath the blazing sun. In the end, many high-ranking officers of the Imperial Guard were winnowed out from the massed retreat and ferried to the landing zones aboard Valkyries. Those taken were the most highly decorated of their kind. Special operations airlifted out High King Tybalt of House Terryn and his remaining Imperial Knights, who returned to Voltoris for much-needed repairs.
In addition to key officers, heavy equipment was given priority. Far away, members of the Departmento Munitorum had rightfully reasoned that it was those items that were far harder to replace than the many millions of men that would soon be abandoned to their fate, though approximately fifty percent of the surviving Astra Militarum ground forces managed to make it off-world before the end came.
After disbanding the Task Force Retribution, Lord Admiral Hawke received a special gift from the Adeptus Mechanicus -- a specialised torpedo warhead capable of unleashing a very particular form of Exterminatus upon Agrellan by the unusual gasses present in the atmosphere of its northern hemisphere into a planetary firestorm.
The Third Sphere Expansion was over.
Mu'gulath Bay burned. The chain reaction sent unnatural firestorms sweeping over the lands of the Tau Sept World. This was beyond the Tau enviro-engines' ability to halt or control. Anything not beneath a protective shield dome was doomed. And only a single shield dome remained -- the massive one that spread over the city that the Tau called Lo'vasht'au. Many millions of Tau died, as did those soldiers of the Astra Militarum left behind by the foe.
When the Kor'vattra finally arrived they did not recognise the planet. The news they brought was worse still. Fires did not burn upon Mu'gulath Bay alone; the strange phenomenon known as the Damocles Gulf had become a roiling inferno. Those labyrinthine passageways through the region that it had taken the Tau so long to discover were untenable once again. For many Terran days, those trapped beyond the vast barrier were faced with the unsettling truth that they might never travel back to the Sept Worlds, that they were cut off forever from the Tau Empire. Communications could pass through the barrier, but starships could not.
Earth Caste engineers, however, were working ceaselessly to perfect a shield that would protect starcraft from the highly corrosive gases. Early tests were positive, as some ships survived the passage across the Damocles Gulf, but the failure rate was high.
Commander Shadowsun had recovered from her wounds, although she still grew weak quickly. As Supreme Commander of the Empire's Fire Caste, she spent long sessions with the Ethereal High Council, for there was much to plan and discuss. Terrible rumours swirled around the Tau Empire, but all fears and doubts were silenced by the announcement that, in a matter of Terran days, Ethereal Supreme Aun'Va would broadcast a speech, his new statement to be beamed across the Sept Worlds and beyond. It was to be a message of hope and courage, a message to be seen by all children of the Greater Good.
Commander Farsight was gone from Mu'gulath Bay, returning to exile in his Farsight Enclaves. His exit was sudden and without notice, for he left before the Ethereal High Council reached the inevitable conclusion that he must be captured and tried for treason to the Tau Empire.
Shadowsun knew she would be ordered to apprehend Farsight by the Ethereal High Council to force him to undergo a Trial of Judgment, a task she knew that she would carry out reluctantly but loyally. In truth, Shadowsun suggested that Farsight leave the system before those orders were given to provide her former ally a head start in making his escape.
Farsight left behind the roiling flames of Mu 'gulath Bay even as the hologram of the dead Ethereal Supreme began its broadcast to the Septs. While his warriors began their dangerous journey home, they listened to Aun'Va's speech. He spoke of the Empire's tragic losses, of how they would make them stronger. He spoke of how, more than ever, enlightenment must conquer savage barbarism. Aun'Va's image spoke of never underestimating their foe again.
It was only near T'lasla -- a planet earmarked for future Tau colonisation -- that the Enclaves fleet had received the distress call. In response, Farsight deployed his forces to the aid of T'lasla -- and the defeat of the Tyranid hordes of Hive Fleet Leviathan.
The events of the Second Agrellan Campaign brought the Third Sphere Expansion to a close. Unable to easily navigate the Damocles Gulf for a time in the wake of the Exterminatus action launched on Mu'gulath Bay, and forced to deal with the political ramifications of the death of the Ethereal Supreme, the Tau Empire paused for a short time in its rapid expansion to lick its wounds. The Tau eventually launched their Fourth Sphere Expansion not long afterwards. But it ground to an almost immediate halt in the early 42nd Millennium due to the birth of the Great Rift, which caused the loss of many of its forces amid the chaos roiling the Immaterium as the Noctis Aeterna descended upon the galaxy. However, the Tau eagerly launched a new venture, the Fifth Sphere Expansion, as soon as the Warp Storms dissipated enough along the Eastern Fringe to allow such a massive undertaking.
The Damocles Gulf Crusade
|Responding to Tau encroachments upon the Eastern Fringe, the Immperium despatches a vast Crusade force against this new xenos threat. The Tau colonies beyond the Damocles Gulf are crushed, the Emperor's armies then falling upon Dal'yth Prime in great force. A desperate war follows, in which Tau Commanders O'Shovah and O'Shaerra eventually stem the Imperial tide, though only at great cost. The retreat of Imperial forces marks the end of the Second Sphere Expansion.|
Great War of Confederation
|From beyond the Western Veil Nebula comes an immense Ork invasion. Ethereal Supreme Aun'Va calmly marshals the entire Empire to defend itself as the Tau'va teaches. Forces from those Septs closest to the threat -- Vior'la, Sa'cca, and Tau'n -- race to engage the foe, stalling the WAAAGH!'s impetus. Meanwhile, O'Shaserra is brought out of suspended animation to command the Tau war effort. In the sprawling conflict that ensues, a new legend, that of Commander Shadowsun, is born. From Vay'harra and Kormusan to the K'resh Expansions, Shadowsun stands supreme as the saviour of the Empire, and eventual vanquisher of the greatest Ork threat in Tau history.|
|Decades of Water Caste diplomatic work has converted many human worlds in the Lagan System. With the help of Expeditionary Cadres, the star system is graded a Class 1 colony, moving steadily towards becoming a fully-ﬂedged Sept. However all this preparation comes to naught as the sector becomes a war zone, targeted for xenos cleansing by the Ultramarines Chapter of the Adeptus Astartes. Many human and Tau colonists are slain as Lagan becomes a slaughterhouse, its cities reduced to smoking ruins.|
The Nimbosa Annexation
|Commander Brightsword, a student of Farsight's way of war, leads an attack to claim the Imperial world of Nimbosa. By the time the Imperium brings reinforcements, the Tau are prepared to defend their new planet. The fighting culminates with the infamous Koloth Gorge Massacre, where the forces of the Astra Militarum are so brutally slaughtered that Brightsword is censured, summoned back to T'au due to the remorselessness of his acts. Since this attack, the planet has changed hands several more times and remains a war zone.|
The Third Sphere Expansion
|The Third Sphere Expansion begins. Vast beyond anything that has come before, it sees the entire Tau race placed upon a war footing. The dynamism with which the Tau seize their destiny is irresistable and dozens of alien races are assimilated into the Empire. Borne far afield by enhanced ZFR Drives, the Tau claim star systems previously beyond their reach and the Empire grows like never before.|
|The first Sept of the Third Sphere Expansion is declared and used as a staging ground for further advancement.|
Defence of the Farsight Enclaves
|With his spearhead of eighty XV8 Crisis Battlesuit Teams, Commander Farsight leads a counterattack against a tendril of Hive Fleet Kraken that has entered his territory.|
|The Tau complete their annexation of what was previously the Imperial desert Mining World of Taros, renaming it T'ros. It becomes the prime planet of a new Sept; its remaining humans considered Gue'vesa citizens of the Tau Empire and congratulated on the wisdom of their decision.|
War Across the Stars
|Across the gulf of space, the Tau Empire knows one victory after another. The awoken Shas'O Kais, another of Commander Puretide's former proteges, seizes triumphs that see the establishment of the Fi'rios Sept. Upon the orders of Aun'Va, the Ghosts of N'dras begin covert operations against the Imperium, detonating the Worldcore on Lamdiah and assassinating Cardinal Ambros the Blessed. Meanwhile, Imperial forces later counterattack and drive the Tau from the Zeist Sector, only to find they have been intentionally sidetracked by Shadowsun, who claims victory elsewhere.|
|An Imperial counterthrust attacks the Tau colonies in the Zeist Sector. The Space Marines drive the Tau from many worlds in the sector, and while the losses are regrettable, the Tau gains elsewhere are on such a scale that, even to the casualty-conscious Tau, Shadowsun's diversion seems not just acceptable, but shrewd.|
|Commander Shadowsun sweeps the armies of the Imperium before her like ships upon a storm-tossed sea. Where her foes spread wide she strikes at their weakest links. Where they dig in and fortify, she bypasses their strongholds to wreak havoc elsewhere. Dozens of Imperial worlds are seized for the Empire. However, upon reaching the Hive World of Agrellan, Shadowsun faces a new strategic challenge. This massively fortified world stands as the gateway to the resource-rich Dovar System and its Gilded Worlds, meaning that it cannot simply be avoided, but must instead be conquered for the Greater Good. Accordingly, the Commander implements a masterful strategy, coordinating over twenty seprate planetary assaults and ensuring each is spearheaded by the newly deployed XV104 Riptide Battlesuits. Despite the efforts of the White Scars, the Raven Guard, the Imperial Knights of House Terryn and multiple regiments of Astra Militarum, Shadowsun's audacious battle plan sees the planet won in a single Terran day. During ferocious fighting around the capital city of Agrellan Prime, a significant portion of the Imperial defenders make good their escape, but even this cannot sour the incredible Tau victory. Yet there is no time for self-congratulation as Shadowsun drives her forces on before the fires of the newly renamed Sept of Mu'gulath Bay have even died.|
|Shadowsun suffers her first major defeat on the Knight World of Voltoris when the Imperial forces, led by the Raven Guard, the White Scars, the Catachan Jungle Fighters and the Imperial Knights of the ruling House Terryn, finally throw back a Tau invasion force.|
The Prefectia Campaign
|Commander Shadowsun returns to form during her assault on the Fortress World of Prefectia, hoping to open the way to the Dovar System for the Empire. The Tau forces overwhelm the Imperial defenders once more through the execution of her brilliant strategems. Kor'sarro Khan, Captain of the White Scars 3rd Company, personally vowed to decapitate Commander Shadowsun, for she had first outmatched him on Agrellan and then escaped his blade again on Voltoris. Using herself as bait, Commander Shadowsun took advantage of the Imperium's fixation on slaying her in order to spring a masterful trap. Many casualties were inflicted upon the Space Marines, including the Raven Guard Chapter Master, Corvin Severax, who was slain by Shadowsun herself, to be replaced by his subordinate Shadow Captain Kayvaan Shrike. Not even a large contingent of Imperial Knights from House Terryn of Voltoris could turn aside the devastating Tau counterattacks. Only through heroic actions were any Imperial forces able to retreat off-planet.|
The Second Agrellan Campaign
|Determined to eliminate the xenos threat to the Eastern Fringe, the Imperium unleashes a massive Retribution Task Force upon the former Hive World of Agrellan, now the Tau Sept of Mu'gulath Bay, the site of the Empire's greatest triumph. The Imperial assault goes well at first but is ultimately blunted by the unexpected intervention of the renegade Tau Commander Farsight, whose forces have traveled from the Farsight Enclaves to aid their estranged brethren. Seeing victory once more eluding their grasp, the Imperium unleashes an Officio Assassinorum Execution Force to destroy the Tau leadership. While Commander Shadowsun is wounded, she survives the assault by a Callidus Assassin. The Ethereal Supreme Aun'Va, trapped on the world by the Imperial invasion, is not so lucky and is slain by a Culexus Assassin. The Adeptus Astartes, Imperial Knights and approximately fifty percent of the Astra Militarum forces deployed for the campaign are recovered before the Imperium delivers its final judgement -- an Exterminatus action carried out by a special torpedo warhead provided by the Mechanicus that ignites the unusual gases of the world's northern hemisphere, unleashing a planetary firestorm that kills millions of Tau and many of the Imperium's own unfortunate troops. In the wake of the disaster, and the effect the ignition also has on the Damocles Gulf, the Third Sphere Expansion comes to a close.|
- Tau Empire
- First Sphere Expansion
- Second Sphere Expansion
- Fourth Sphere Expansion
- Fifth Sphere Expansion
- Codex: Tau Empire (6th Edition), pp. 17-19, 25, 29
- Codex: Tau Empire (7th Edition), pp. 8, 40-42
- War Zone Damocles: Kauyon (7th Edition), pp. 5-8, 99-101
- War Zone Damocles: Mont'ka (7th Edition), pp. 3-113
- Warhammer 40,000: Rulebook (8th Edition), pg. 134