Centurion War

The Centurion War was a massive conflict that place in the Centurion Sector and Drameara Expanse, a large region of Imperial space located on the western edge of the Segmentum Obscurus near the Helican Sub-Sector. This conflict was the result of the hubris of the rogue Fabricator-General, Atilla, of the forge world of Iternium. Dissatisfied with the Emperor's imposed limitations into the study of the forbidden sciences, such as cybermancy and most especially the development or study of Silica Animus (Abominable Intelligence or A.I.), he continued his forbidden research, despite repeated warnings from the Martian Priesthood. It is not entirely clear how Atilla managed to turn a half-dozen forge worlds and a significant portion of the armies under his command against the Emperor, but he was known to be a very skilled and persuasive leader who earned immense personal loyalty amongst his peers and subordinates. The Fabricator-General won over the loyalty of many of his fellow sector Fabricator-Generals after promising them the lost secrets of ancient Standard Template Construct technology and the ability to research the forbidden sciences at will.

He also garnered the support of two Space Marine Chapters, including the Knights of Guilliman and the Grey Gorgons as well as several million troopers from the local PDF, Astra Militarum and militia forces of the sector. With this powerful army, Fabricator-General Atilla and his cohorts broke away from the Imperium. The resulting conflict would draw in millions of military forces from the Imperium and result in the destruction of several worlds and deaths of billions within the sector, leaving this region of space a desolate wasteland and vulnerable to the predations of xenos raiders and secessionist forces within the region. This sector has remained in a constant state of warfare for over a century since the end of this conflict.

The Seeds of War are Sown (781-931.M41)
The reasons behind the coming war are not known in great detail, but Imperial scholars have pieced together some parts of the story. It seems that Fabricator-General Atilla was always known as being a highly arrogant and paranoid individual who chafed at the limitations imposed by the Imperium and longed to delve into technologies that were forbidden. He was appointed Fabricator-General of Iterium sometime in 681.M41, and soon began to conduct experiments into these banned technologies. This soon brought him to the attention of his superiors who ordered him to stop. But he paid no heed to these demands, and in fact, increased his work. In his goal of creating his own empire he persuaded the Fabricator-Generals of 6 other forge worlds to unite under his command and secede from the Imperium.

Knowing he would not be allowed to go peacefully he set about creating an army to do his bidding, using the power of 7 Forge Worlds, he set about creating an army that he believed would be enough to break away. To this end, he also used the long standing ties of his world to the vaunted Knights of Guilliman Astartes Chapter and to the Grey Gorgons, to convince them that his goals were honest. During the coming war, these two Chapters would commit themselves fully to Atilla and his plan, much to the ruin of them both. Allied to these formidable forces was the Atilla Legion - an army 100 million-strong created - from both local Planetary Defence Forces and Astra Militarum regiments in the Cluster, along with tens of millions of poorly trained, but very well-equipped Imperial militia units from the worlds of the Cluster. The soldiers of the elite Atilla Legion units were equipped with a lighter type of power armour similar to that worn by some Inquisitors, as well as with human-sized boltguns. Further strength was added from the massed Skitarii Regiments of the forge worlds along with Titans and Imperial Knights based there. Against virtually any foe, this powerful army would sweep all before them, but Atilla knew that the Imperium would commit vast forces to retake these important worlds, but despite the risk, he was set on his path and plunged his worlds into war.

The War Begins (931.M41)
The opening actions of the war were not the all-out attack that was expected, but rather a series of small raids carried out by elite Astartes units against known Imperial strongholds. The goal was to cripple the Imperium's ability to react swiftly. With these outposts removed, Atilla was able to launch his first major offensive against the holdout forge world of Lycan. Lycan was very important, as the only stable warp lane into the sector exited at this forge world, and so, the system became the main hub for all outgoing and incoming trade. Lycan was also intended to serve as an example of what happened to those who defied Atilla.

Secessionist Advance and Invade Lycan V, Corinth Holds Out (931-939.M41)
For the next few years the secessionists advanced and conquered several worlds, but several who refused to join Atilla would defy him, including Corinth, who would in a heroic stand that would go down in legend, and Lycan itself. Using a series of diversionary attacks Atilla was able to move his army into position above the world and with a single word the massed fleet opened fired, and soon the world's defences were neutralised, with very little loss to the secessionists. The fleet, led by the battle barges of their Astartes allies, soon directed their fire against the ground defences in order to allow the transports an unhindered approach to the landing grounds with the astartes striking at the command centres and major defence positions. The ground assault soon followed, and despite taking casualties, the Atilla Legion was able to gain several footholds and the Skitarii, Knights and Titans of Lycan were forced back into prepared defence positions on the northern continent and hunkered down to wait for the reinforcements that were certain to come.

Reinforcements, however, were not soon in arriving and it took two years for the first Imperial troops to arrive. The first of which was a Great Company of the Space Wolves Wolf Lord Erik Olafsson. He arrived to find a world under siege and began immediately to asses the situation. Thanks to the few transmissions that managed to get through the traitor's communications blockade, he learned that over the past 2 years the Atilla Legion had launched repeated attacks against the Skitarii of Lycan but had not been able to break the defensive lines and the war had become a stalemate with neither side moving much from their own lines. The Space Wolves wanted to launch an immediate attack to break the siege but were forced to wait due the strength of the traitor naval forces. But they would not have long to wait as the entire Ash Scorpions Chapter and a massive Imperial Navy and Astra Militarum forces were only mere days away.

Space Wolves recalled to Fenris, Corvo named Supreme Commander (936.M41)
With the power of an entire chapter behind his own forces, a Great Company and the Imperial Navy, the attack began in earnest. The traitor forces put up a significant fight but were unable to cope with the righteous fury of the Astartes. They were able to break through the blockade and launched the attack against the rear of the traitors in their siege lines. the fighting was fierce but over a number of days, six full Astartes companies and 30 Astra Militarum regiments landed, and they soon surrounded the traitors. In space, the fighting was just as brutal, but the traitors were forced to disengage from the fighting and fled back to the warp. Despite these successes, the Imperials did not have it all their own way as 30 vessels were cripelled or destroyed and thousands of guardsmen were killed, but the most telling casualty was Wolf Lord Erik Olafsson himself, who was killed leading a boarding attack against the Knights of Guilliman's flagship, Konor's Honour. With the failed attack, the Space Wolves disengaged and informed the Ash Scorpions that honour dictated that they return to Fenris to elect a new Wolf Lord. In most circumstances, the loss of a Great Company would be disastrous, but more Astartes units had arrived, including the Chapters of the Skull Reapers and Corvus Legion as well as companies from the Halo Dragons and Imperial Fists.

An enclave of Chapter Masters soon convened and elected Commander Corvo of the Ash Scorpions as Magister Militum (supreme commander) of all Imperial forces.

Increasing Numbers of Astartes join the War (936-939.M41)
Over the following years, following the attack on Lycan, significant numbers of Astartes Chapters flock to the war.

Corvo Launches Trident Plan, Battle of Sigma, Chaos Warships Encountered in Centurion Sector (937.M41)
While the fighting on Lycan raged on, Corvo was preparing the next phase of the war. The road to Iterium and Atilla, using the Lycan System as a springboard, the Imperial forces were to attack in three separate wings. The left wing would move through the Extal and Dorn's Light systems on towards the forge world of Undine, but would first have to destroy the traitor forces around Sigma. This would not be easy and Corvo dispatched significant forces including elements from 6 Astartes chapters led by Captain Pardis of the Halo Dragons 2nd Company. The fighting was especially brutal as Atilla had turned Sigma into a fortress world and forced the world's entire population to manufacture arms and other weapons of war. The Battle of Sigma marked the first occasion of human wave attacks as the civilian populations were used as cannon fodder to deplete the Imperial's ammunition and sap their morale, but victory was soon achieved and Sigma was marked as secured. Chaos warships were also noted in the Centurion Sector for the first time and the librarians of the the chapters warned of major disturbances in the warp.

Lycan V Liberated (939.M41)
This was a major turning point in the conflict as Lycan was finally liberated after 6 years and millions of casualties.

Secessionist Forces On The Defensive (939.M41)
With Lycan liberated and Sigma neutralised, Corvo was free to implement the next stage of his plan. Two more army groups would launch their attacks. The centre, led by Corvo, was to be directed at Lytonus, while the right wing would strike towards Granitan. The fighting would be intense as hundreds of worlds lay between the Imperial forces and their ultimate goal - Iterium.

Flesh Rippers Arrive and Destroy Knights of Guilliman, Massacre at Albion (940.M41)
With the war now nine years old, the number of Astartes and Imperial forces arriving were growing monthly, and this year marked the arrival of a force that would go down in infamy and would change the war in an unexpected way. During 940.M41, as the war finally began to turn in favour of the Imperial forces, Lord Commander Corvo (Chapter Master of the Ash Scorpions) was informed by his Chief Librarian that a significant force was making their way through the Warp and break into realspace behind Corvo's main force. Fearing that it was secessionists, he removed his entire Chapter from the fighting against the Knights of Guilliman and prepared for the arrival of this unknown force. What emerged from the warp was not what Corvo had expected. A full Astartes Chapter had arrived. This new Chapter immediately began broadcasting that they were friendly and even lowered their shields to show peaceful intent. They offered a parlay on the nearby world.

Leading a single squad Corvo met with these unknown Astartes and though he was wary of them, his Chief Librarian stated that he believed that they were not followers of the Dark Gods but nor could he certain they were followers of the Imperium. The unknown Astartes introduced themselves as the Flesh Rippers, a name Corvo dimly recalled hearing before, and their leader named himself Captain Moloch of the 10th Company. He told Corvo that the Lord Reaper would only talk through him. Over the course of several hours the two parties conversed until finally Corvo was convinced that the Flesh Rippers were true to the Emperor at least, and so, with some reservations he allowed them into his order of battle. Following this meeting, Lord Reaper Uric Draf led his entire Chapter against the Knights of Guilliman on their homeworld of Jorvick.

The Knights of Guilliman were a proud and storied chapter that though no fault of their own, had found themselves fighting on the wrong side against the Imperium. The reason behind this decision dates back a thousand years, back to when the Knights of Guilliman fought to defend the Iterium System from the foul Aeldari. At the height of this conflict, they, and Iterium's Fabricator-General, swore a binding oath to help each other when needed. With their homeworld close to the Centurion Cluster their choice was clear and they entered the war on the side of the Secessionists. They were however, an unreliable ally, as their loyalty to the Emperor and the Imperium warred with their sense of honour and the need to honour their oath. They never operated under the command of Fabricator-General Atilla and had few of his units in their ranks, and attempted to end any engagement with words rather than bolter and blade. Any foe that was beaten was granted passage to rejoin the Imperial Forces.

By 940.M41, they had however, grown tired of the war and desired to end its involvement and they began to believe that they had been deceived and that Fabricator-General Atilla, the Grey Gorgons and the other Fabricator-Generals had been corrupted and turned to Chaos, but they would not get the chance to end it peacefully. Recalling the entire Chapter and those units of the Atilla Legion that also wanted to end the war back to Jorvick, they began to prepare to surrender and submit themselves to the Emperor's Judgement, when an Imperial Force arrived in orbit, led by the Flesh Rippers. Any attempt to talk was ended as the Flesh Rippers' fleet opened fire on the Knights' fleet, and soon, a great battle raged in orbit as the secessionists fought back. With the help of the Imperial Navy who kept the Knights' ships and orbital defences at bay, the Flesh Rippers launched their entire Chapter into a massive assault against the world of Jorvick. Hundreds of drop pods and gunships roared through the atmosphere crashing into the ground outside the walls of the Fortress of Konor.

Led by their Chapter Master, the Flesh Rippers erupted from their drop pods and thunderhawk gunship and without heeding injury or loss, they hurled themselves at the walls. The Knights of Guilliman leapt to meet them, matching the Flesh Rippers' pure fury with pure determination. For nine blood-drenched hours, the two chapters fought in the most vicious fighting imaginable, until finally a ramp of corpses led up to a single breach in the wall, and the Astartes of the Flesh Rippers Chapter plunged in. Filled with rage, they were merciless. By the time the Salamanders, who were supposed to support the Flesh Rippers, arrived, the battle was all but over. The inside of the fortress was a slaughter house, filled with the dismembered and mangled corpses of the defenders, for not one soul had been spared from the fury of the Flesh Rippers. It was an absolute slaughter, the fortress having been transformed into an abattoir of mangled Astartes.

The Knights of Guilliman were all but destroyed and Corvo, though pleased that such a powerful force had been eliminated, was disgusted by the Flesh Rippers' actions. He called a meeting with the other chapter masters to discuss what was to be done about them. They unanimously agreed that the ferocious Chapter needed to be reigned in, and Corvo dispatched the Corvus Legion, Skull Reapers and Charnel Brethren Chapters to watch over them and lead the right wing in their campaign against Granitan. He hoped that the presence of 3 other chapter masters and their chapters would be enough to make sure that the Flesh Rippers were restrained in the future.

In this, Corvo was mistaken, as the next attack on Albion would descend to new depths.

Abion was an agri-world located not far from the Jorvick System, 10 regiments of Atilla Legion had been stationed there and Shadow Lord Rhargrimm (Chapter Master of the Corvus Legion) was determined to take it. He dispatched the Flesh Rippers and Charnel Brethren, along with 10 regiments of Astra Militarum troopers. The plan was simple, the guardsmen would land first and engage the Atilla Legion, while the two Astartes chapters would drop right into the heart of the defences and destroy the traitors from the inside. At first, the plan proceeded smoothly but Imperial Guard commanders soon realised something was wrong when the Atilla Legion began pouring towards the Imperial line. The senior Imperial Guard commander, Colonel Tayle, saw in the faces of the soldiers, absolute terror, and they displayed no fear of the massed guns of the Astra Militarum forces, only a desire get away from whatever was attacking them. The Colonel soon saw what it was - the Flesh Rippers and Charnel Brethren, apparently driven mad by some kind of battle-frenzy, crashed into the Atilla Legion's rear ranks, just as the first soldiers reached the loyalist Astra Militarum's lines.

The crazed Space Marines fell upon the Atilla Legion in an orgy of bloodletting. Many Astartes had removed their helmets, and eschewing the use of pistols and other ranged weapons, set about the soldiers with chainsword, chain-axe, combat knife and even their own teeth. Colonel Tayle witnessed in mute horror, Astartes ripping out the throats of men with their bared teeth. The raw fury and love of carnage he saw in their faces, as they literally tore the enemy apart, made him shudder in fear. The traitor forces were annihilated within minutes of the Space Marines' brutal attack, but the small number of the enemy were simply not enough for the Flesh Rippers and Charnel Brethren, who by now seemed to have been driven into a fever pitch of absolute bloodlust. With no more traitors for them to butcher, they scrambled over the breastworks of the Astra Militarum regiments and smashed into their own line. Properly driven into a true battle frenzy now, the Flesh Rippers and Charnel Brethren performed acts of the most debauched nature, in the name of violence.

Every guardsmen they found, fell beneath their blades. Even though they were allies, none were spared by the Marines crazed attack. Colonel Tayle and several companies were only just able to make it back to their drop ships, and soon fled to the safety of their ships, leaving behind terrified and helpless civilians to face these crazed Astartes alone. Colonel Tayle later reported that he had personally witnessed cannibalistic acts committed by the frenzied Space Marines. Colonel Tayle was able to report back to his commanders and to Lord Commander Corvo all that had happened on Albion. The Inquisition was informed of these events, and the matter would have to be handled at a later date, but for now, such matters had to be pushed aside as other events had forced Corvos's hand. Forces of Chaos had been conclusively identified and were increasing in number at each passing week. The matter of the Flesh Rippers and Charnel Brethren would have to wait until the war was over.

Imperial Left Wing Halted at Undine VIII (942.M41)
Eleven years had passed since the outbreak of this conflict and the situation was stable - dozens of worlds had fallen to the Imperials - but the massive forge world of Undine was the next target and this would not be easy to capture. Undine was the third largest forge world in the sector and had a standing army of some 8 million-strong and it was defended by a ring of orbital stations and a significant naval presence. These formidable defences were further augmented by massed defence silos and ground lasers which surrounded the manufacturing hubs. Most significantly, was an entire Titan Legion called the planet home and the nearby Knight World of Undine VI would also need to be taken. Lady Marshall Kasteen was fully aware that Atilla would defend these important worlds with all available forces, and so she dispatched an entire Astra Militarum army group - some 3 million troopers strong - and elements from 3 separate Titan Legions and numerous Imperial Knights to take it as swiftly as possible. She placed these forces under the command of Lord General Nayle. Undine VI was taken swiftly, as all but 3 of the worlds the Knights had been dispatched to defend Undine VIII, leaving it vulnerable to a swift assault from over 30 Knights who broke the defences, before moving onto the main target of Undine VIII, but thanks to a series of mistakes and general incompetence from Nayle, even the massive force that was assembled was unable to capture the world, and like Lycan, the fighting descended into a stalemate that would last four years.

Flesh Rippers, Charnel Brethren, Skull Reapers and Corvus Legion Retire from War (942.M41)
For reasons that have yet to be determined, these 4 chapters retired from the fighting immediately.

Liberation of Corinth, Largest Naval Action of War, Chaos Revealed (944.M41)
While the left wing of the Imperial crusade forces were busy fighting at Undine, the center was moving swiftly forwards and liberated the major hub of Corinth, which thanks to the Corinthian Dragoons Regiments, had held out for twelve years. At the same time, the largest naval action of the war took place at Oberon as Imperial forces clashed with the traitors in a battle that numbered close to 200 vessels. The Imperial Navy emerged victorious but badly mauled in the fighting and 47 ships were lost. It was during this year that chaos was suspected to be behind the war, thanks to an Imperial Assassin that brought the news back from a failed attempt on Atilla's life.

109th Siege Army Destroyed at Radium I (945.M41)
Whilst the fighting at Undine was underway, Lord General Nayle, commander of the 31st Siege Army Group, attempted to end the stalemate by launching an attack against the nearby forge world of Radium and hoping to draw away the stream of reinforcements that Atilla was sending to Undine. By attacking Radium, Nayle also hoped to divert attention from his failing at Undine. The 109th Army that was designated to capture the world was made up of new recruits and was badly under-equipped to fight on Radium which was, as it's name suggested, a barren wasteland covered in noxious fumes and high levels of radiation - the legacy of thousands of years of industrialisation. Anyone not wearing appropriate protective gear would be killed within hours. Nayle did not care that his troops would be killed in their thousands and ordered the attack. Nayle also ignored the reports that massive Chaos forces were present on Radium. The result was as expected, those few troops not killed by the massed ranks of chaos cultists and Traitor Marines were killed by radiation. Nayle would pay the price for his stupidity and was arrested by the senior commissar of Lady Marshal Kasteen and executed by Lord Inquisitor Diemos. Lord General Krag was appointed in his place. Krag immediately set about rectifying his predecessor's mistakes and dispatched the 3rd and 10th Siege Army, along with Skitarri forces from Lycan to take Radium. These two army groups and their Mechanicus allies were battle-hardened veterans and with the guard formations equipped with protective suits, they were finally able to fight on equal terms with the world's defenders. The centre wing at this time were able to capture Lytonus and continued their advance.

Largest Tank Battle of War at Radium I, Capture of Radium I, First Encounter with Bringers of Change (945.M41)
The war for Radium would be swift but brutal, as massed tank regiments fought over the barren ground. Eventually through sheer will, the Imperial forces pushed the chaos forces back and captured the world. Meanwhile at Kalen, the Novamarines would encounter for the first time, the Bringers of Change Chaos Warband and confirm, once and for all, that chaos had indeed corrupted Atilla.

Iron Snakes Suffer Heavy Casualties on Hive World Likal III, Ash Scorpions Divert to Undine VIII, Capture of Undine VIII, Imperial Navy Task Force Destroyed at Obtine V (946.M41)
In 946.M41, the war would take a major turn as fighting continued across the sector. At Likal,the Iron Snakes Chapter would suffer heavy casualties fighting amongst the hives of Likal against Heretic Astartes. Meanwhile, Lord Commander Corvo, impatient to finish things at Undine, moved his entire Chapter to the world and in heavy fighting, finally captured the world. Admiral Priett, left in command of the centre, would attempt to move swiftly and led a task force to Obtine, but was met with massed fire from numerous Traitor vessels. Admiral Priett and over 100,000 crewmen were killed. Lord Commander Corvo ordered elements from four chapters and four entire fleets to Obtine, and soon, the Imperials were able to land ground forces and fighting broke out across the surface.

Titans Clash at Obtine V, Obtine V Destroyed by Exterminatus (947.M41)
Unable to break the traitor lines on Obtine V, the Imperials deployed Titans and Knights and pushed back the traitors enough to shell the main manufactorum. Choas forces responded by unleashing a plague virus and plague zombies. Determining that the world was lost, Corvo ordered a retreat from the surface and destroyed the doomed world from orbit through Exterminatus.

Setback at Granitan, Imperial Left Wing Disbanded and Sent to Granitan, Astartes Forces diverted to Granitan, Massive Daemon Incursion at Likal VI (948.M41)
The Imperial right wing continued their advance towards Granitan but faced heavier resistance from chaos forces and were increasingly forced to slow their progress, but nevertheless, managed to force their way though, and soon, the twin forge worlds of Granitan were under siege. But large chaos forces counter-attacked and in a series of battles, forced the Imperial Navy out of the system, leaving the Imperial ground forces vulnerable and without orbital support. Lord Commander Corvo ordered all available Astartes forces to Granitan, he also disbanded the left wing and moved them to Granitan. His center increased their advance and moved towards Granitan. After several months of fighting the Imperial forces regained control of the system and were able to resupply the Astra Militarum units on the ground, but the battle would take a further four years before the world was declared secure. Meanwhile at Likal, the Grey Knights were fighting the largest daemon invasion of the war, emerging victorious, but only at great cost.

Final Assault on Iterium System (952.M41)
Once Granitan had been taken, the Imperial forces began preparing for the final attack on Iterium. Corvo knew that he faced not only the Dark Gods' mortal servants but also a massive numbers of daemons. When the Imperial force finally appeared over Iterium, the fighting took on a whole other appearance. It would take two years for the world to be subjugated. During the fighting the Daemon Prince Charon manifested. Atilla was able to make good his escape, along with the Traitor Marines, but millions of Chaos cultists were left behind to be destroyed.

The War is Brought to a Close (954.M41)
After twenty-three years of constant fighting, the war was finally over, but a heavy price had been paid - billions were dead and the sector was now a barren wasteland, and the 7 forge worlds that had been at the heart of the war had been left completely unusable. The Imperial forces withdrew and were sent to other warzones leaving the sector undefended. Orks, Aelderi and other xenos moved in and carved out territories of their own, and from the world of Pythonus, a snake-like reptilian race began to forge themselves an empire. From the nearby Koronus Expanse, Rak'Gol Marauders soon arrived, forcing the Inquisition's Ordo Xenos to despatch a Deathwatch task force  to deal with this new alien threat and fight yet another war for control of the Centurion Sector.

Order of Battle Centurion War (931-954.M41)
==== Imperium of Man==== Senior Commanders Lord Commander Corvo - Chapter Master of Ash Scorpions, overall commander Master Zahariel - Lions Malevolent 3rd Company Captain Master Anaziel - Dark Angels 4th Company Captain Captain  Adrax Agatone - Salamanders 3rd Company Captain Captain Mordacai - Novamarines 4th Company Captain Lord Reaper Uric Draf - Chapter Master of Flesh Rippers Reaper Captain  Moloch - Flesh Rippers 10th Company Captain Lord Michaelus - Chapter Master of Charnel Brethren Iron Lord Severon - Chapter Master of Skull Reapers Shadow Lord Rhargrimm - Chapter Master of Corvus Legion Wolf Lord Erik Olafsson - Space Wolves Wolf Lord Marshal Titan - Black Templars Crusade Marshal Captain Pardis - Halo Dragons 2nd Company Captain Cannoness Anastasia - Cannoness of the Order of the Emperor Resplendent Magos Dominus Balthasar - Fabricator General of Lycan Marchioness Elyssa Van Lycan - Lady of the Knight World Lycan VIII Princeps Alyssa Van Lycan - Senior Princeps of Legio Canis Lady Marshal Kasteen - Supreme Commander Astra Militarum Lord General Nayle - Commander of 31st Siege Army Group(Executed 945.M41) Lord General Krag - Commander of 31st Siege Army Group Lord General Vambrac - Commander of 110th Siege Army Group Lord General Imhorst - Commander of 203rd Siege Army Group Lord General Pial - Commander 17th Assault Army Group Lord General Ambelane - Commander 18th Assault Army Group Lord General Sturmm - Commander 94th Assault Army Group Lord General Jurgen - Commander 100th Assault Army Group Lord Admiral Pellas - Command of Imperial Navy Forces

Adeptus Astartes Ash Scorpions - Entire Chapter Novamarines - 2 Company's Lions Malevolent - 4 Company's Dark Angels - 1 Company (948.M41 to 954.M41) Salamanders - 1 Company Flesh Rippers - Entire Chapter (940.M41 to 942.M41) Griffon Lords - 2 Company's Imperial Fists - 1 Company Black Templars - 1 Crusade Space Wolves - 1 Great Company (931.M41 to 936.M41) Emperors Wolves - 1 Company Iron Snakes - 6 Company's (940.M41 to 954.M41) Charnel Brethren - Entire Chapter (940.M41 to 942.M41) Corvus Legion - Entire Chapter (936.M41 to 942.M41) Skull Reapers - Entire Chapter (936.M41 to 942.M41) Halo Dragons - 7 Companys (934.M41 to 954.M41) Red Hunters - 3 Companys (935.M41 to 954.M41) Grey Knights - Unknown

Imperial Guard 31st, 110th, 203rd Siege Army Groups 17th, 18th, 94th, 100th Assault Army Groups with the following Regiments Corinthian Dragoons - 1 Regiment Cadian Shock Troops - 139 Regiments Death Korps of Krieg - 51 Regiments Mordian Iron Guard - 17 Regiments Praetorian Guard - 7 Regiments Vresh Grenadiers - 9 Regiments Faeburn Vanquishers - 2 Regiments Elysian Drop Troops - 1 Regiment Tempestus Scions - 2 Regiments Athonian Tunnel Rats - 6 Regiments Vostroyan Firstborn - 3 Regiments Miasman Redcowls - 3 Regiments Valhallan Ice Warriors - 27 Regiments Hundreds of other Regiments whose names have not been recorded Unknown Number of Penal Regiments

Sisters of Battle Order of the Emperor Resplendant  - 11 Companys

Imperial Navy + Astartes Fleet Assets Battlefleet Centurion 11 Battleship's 19 Battle Cruisers 23 Front-Line Cruiser Squadron 51 Light Cruiser Squadrons 78 Escort Squadrons 8 Battle Barges (Ash Scopions 1, Flesh Rippers 1, Charnel Brethren 1, Halo Dragons 1, Black Templars 1, Skull Reapers 2, Corvus Legion 1) 47 Strike Cruisers 86 Escort's 1 Ark Mechanicus Battleship (Lycan V)

Adeptus Mechanicus Forces Forge World Lycan V (Skitarii - 10 Regiments, House Lycan based on Lycan VIII - 18 Knights, Legio Canis - Entire Legion) Legio Invigilata - 3 Maniples Legio Ignatum - Demi  Legion House Terryn - 38 Knights

Forces of the Inquisition Lord-Inquisitor Deimos - Ordo Hereticus Senior Inquisitorial Representative Inquisitor Vale - Ordo Malleus Inquisitorial Task Forces - CLASSIFIED Grey Knights - CLASSIFIED

Officio Assassinorum Agents - CLASSIFIED

Templars Psykologis Disruption Squads - 7 Augur Teams - 1

Secessionist Forces
Senior Commanders Fabricator-General Atilla - Senior Magos in charge of the 7 Forge Worlds of the Centurion Cluster - secretly a devotee of Chaos Lord Marius Gage Kruger - Chapter Master of the Knights of Guilliman Lord General Ligrus - Commander of Atilla Legion High King Litanus tar Iterium - Lord of the Knight World Iterium III Admiral Apolynia - Imperial Navy Secessionist, commanded fleet assets

Chaos Commanders (after 940.M41) Charon - Deamon Prince of Tzeentch Lord Thanatos - Sorcerer Lord devoted to Tzeentch and Charon, Commander of the Bringers of Change Lord Lucius - Chaos Lord of the the Bringers of Change Lord Severus - Chaos Lord of the Night Lords 38th Company Lord Amillus - Chaos Lord of the Alpha Legion 20th Company

Secessionist Adeptus Astartes Chapters (To 940.M41) Knights of Guilliman - Entire Chapter Grey Gorgons - Entire Chapter (Became Bringers of Change)

Chaos Warbands Bringers of Change (Grey Gorgons)- Entire Force Oracles of Change - Entire Force Night Lords 38th Company - Unknown Force Alpha Legion 20th Company - Unknown Force The Purge - Entire Force Skyrar's Dark Wolves - Unknown Forces Flickering Blades - Unknown Forces Angels of Ecstasy - Entire Force The Flawless Host - Unknown Force Swords of Khargoth - 30 Chaos Marines Extinction Angels - Entire Force Lords of Decay - Entire Force Warriors of Mayhem - Entire Force Gladiator Group 138 - Unknown Forces Angron's Chosen - Unknown Forces World Eaters - Unknown Forces Death Guard - Unknown Forces Word Bearers - Unconfirmed Sightings Iron Warriors - 2 Grand Companies

Chaos Cultists and Mutants + Daemon Forces (Encountered after 941.M41) Estimated 100 Million + of Cultists, Mutants and Daemons

Secessionist  Imperial Navy + Astartes Fleet Assets + Chaos Fleet Assets (Chaos Forces after 937.M41) 9 Battleship's 19 Front-Line Cruiser Squadron 41 Light Cruiser Squadrons 56 Escort Squadrons 3 Battle Barges (To 940.M41) 9 Strike Cruisers (To 940.M41) 23 Escorts (To 940.M41) Unknown number of Chaos Vessels (after 937.M41)

Secessionist Adeptus Mechanicus Forces Forge World Iterium VI  (Skitarii - 17 Regiments, House Iterium based on Iterium III 59 Knights, Legio Draxon) Forge World's Granitan IV + Granitan V (Skitarii - 17 Regiments, House Granitan Based on Granitan VI 37 Knights, Legio Osedon) Undine VIII (Skitarii - 9 Regiments, House Undine based on Undine VI 37 Knights, Legio Ostrom) Forge World Lytonus III (Skitarii - 4 Regiments) Forge World Locan V (Skitarii - 6 Regiments) Forge World Radium I (Skitarii - 5 Regiments) 1 Ark Mechanicus Battleship (Iterium VI) Legio Audax- Demi-Legion (after 940.M41) Traitor Knights Traitor Titans

Auxiliaries Atilla Legion - Estimated at 100 Million+ including secessionist Imperial Guard Regiments

Outcome
Attacker    Imperium of Man Defender    Secessionist Forces, Chaos Forces Attacking Commander Lord Commander Corvo(Ash Scorpions) Defending Commander     Fabricator-General Atilla, Lord Thanatos(Bringers of Change) Date    931.M41 to 954.M41 Scale    Crusade Theatre     Centurion Sector, Segmentum Obscurus

Strength (Attackers) Elements from 16 Astartes Chapters, 2 Imperial Guard Army Groups, Imperial Navy, Inquisition, Adeptus Mechanicus.

Strength (Defenders)    2 Astartes Chapters, Atilla Legion, Secessionist Imperial Guard, Navy Forces, Secessionist Adeptus Mechanicus Forces, 13 Chaos Space Marine Warbands, Chaos Cults, Mutants.

Casualties (Attackers)    Significant: Imperial Guard, Est 140 Million+ Casualties + 9 Billion+ Civilians: Imperial Navy, 7 Battleships, 138 Cruisers and 171 Escorts destroyed: Adeptus Mechanicus, Est 40,000 Casualties, 17 Titans, 94 Knights: Adeptus Astartes, Est 1,000+ Astartes Casualties, 8 Strike Cruisers, 27 Escorts

Casualties (Defenders)    Significant: Secessionist Forces, Est 30 Billion+ inc Civillian Casualties, Heavy Naval Losses. Chaos Forces, Est Millions Chaos Cultist Casualties, 1,000+ Chaos Space Marine Casualties.

Status    Pyrrhic Imperial Victory

Outcome    Secessionist and Chaos Forces Destroyed but Many Escaped into Warp, Imperial Astartes Chapters Badly Depleted, Centurion Sector Largely Rendered Uninhabitable.