|Date||2863 - 294X|
|Location||Byzantine Imperium, Tau Dead Sectors|
|Casus belli||Tau subversion of Imperial authority on Ephesus|
|Result||Decisive Imperium/Haruhiist victory
The Imperium-Tau War was a series of military conflicts primarily involving the Byzantine Imperium and the Tau Empire, with the Holy Empire of Haruhi Suzumiya involving itself alongside the Imperium during the Great Crusade phase of the war as a direct result of the concurrent Directorate War.
First Contact with the TauEdit
The Byzantine Imperium first encountered the Tau when one of their trading fleets entered one of the outer colony sectors. At first, the Tau appeared to be a peaceful race, willing to trade and establish relations with the Imperium. While the Imperium received the Tau gladly, few knew what would happen next.
Initially, relations between the two were cordial. The Tau offered technologies more advanced than some of the technologies the Imperium had, which were received gratefully. The Tau also began sending missionaries preaching their race's religion, centered on the concept of the "Greater Good." At this point in history, the Imperium was far more tolerant of other religions, and the Tau were allowed to practice and proselytize their faith; however, Orthodox Catholicism had a far stronger hold on the Imperium's population, and few paid any mind to the Greater Good.
While the Tau were certainly welcomed by humanity, the reverse did not exactly apply; while humans were free to frequent the Tau colonies, they were completely barred from visiting the Tau core worlds. This perplexed Imperial leadership, as they could not understand why the Tau core worlds were off limits when the Imperium had received the Tau in open arms. Regardless, the Imperium's intelligence agency began pursuing covert operations, seeking to find out why the Tau had refused human contact in their core worlds. They soon discovered that the Tau kept the majority of their military might in the core and that the Tau had fairly large and advanced armies. Within the Imperial government, considerable debate took place as to whether to the Tau's refusal to allow humans to visit their homeworld was out of a desire to conceal their military; suspicious of the Tau's motives, the Imperium began a quiet build-up of its own armed forces.
The Ephesus InsurrectionEdit
Things came to a fore in 2863 when one of the Imperium's outer colonies, Ephesus, rebelled against Imperial authority. The insurrection took the Imperium completely by surprise, as there was no evidence beforehand hinting that the colony's inhabitants were in any way dissatisfied with Imperial rule. The Imperial Guard was immediately dispatched to Ephesus to quell the unrest, fearing that such a rebellion would spread to the other colonies and permanently shatter the legitimacy of Imperial rule.
The rebellion was crushed swiftly, with the Imperial Exarch and a member of the Tau Ethereal caste among the dead. Further forensics and investigation of the data collected from the planetary goverment archives yielded evidence that the Tau Ethereal had persuaded the Imperial Exarch into joining the Tau Empire through pheromones and bribery. The Tau Ambassador was summoned, and an explanation was demanded. However, instead of an explanation, the Tau Ambassador gave an ultimatum to the Imperial leadership: The Byzantine Imperium must submit and join the Tau Empire. Emperor Sergius XI simply replied, "Never. Begone, before my patience runs thin." With that, the Imperium's armies and navies were raised to full alert to await the impending Tau invasion.
The First WarEdit
With the Tau declaration of war in 2863, the Imperium began a mass mobilization of its military to meet the enemy's forces. The Tau struck Ephesus in the Ephesus Sector first, where they were met by Imperial Guard and Imperial Navy elements who had recently finished quashing the rebellion and were now on full alert for any Tau attack. The Battle of Ephesus lasted for weeks, both on the ground and in space; while the Tau were eventually repelled, the Imperial forces had suffered staggering casualties and were just barely able to hold onto Ephesus. While the Battle of Ephesus raged, Tau forces struck on other fronts, managing to take another planet in the Ephesus Sector despite the Imperium's best efforts; Imperial forces later retook that world two months after it fell to the Tau. Heavy fighting also took place in other frontier sectors of the Imperium, and millions of Imperial Guard and PDF troops were thrown into the fires of war.
Despite being largely unfamiliar with Tau technology and caught off guard by the sheer speed of the enemy attack, the Imperial forces fought with true courage and determination. Overall, the Imperial Armed Forces were able to hold the Tau at bay despite sustaining heavy losses. Millions of troops were killed, but over a billion Imperium civilians were killed in the ensuing slaughter. Tau bombardment of Imperial targets was often indiscriminate, and the Tau used nuclear explosives to penetrate deep bunkers, killing civilians hiding in emergency shelters. The Emperor ordered the Science Guild to delve deeply into Tau technology in order to find weaknesses for the Imperium to exploit and to develop new technologies to help the Imperium fight the Tau on an equal footing. It was during this time that the majority of Imperial troops were augmented with cybernetics to improve their fighting ability. Most significantly, the Emperor ordered the initiation of the Imperial Astartes project, taking advantage of the Imperium's expertise in bioengineering, genetics, and cybernetics in order to produce the ultimate soldier. The Imperial Navy also saw the adoption of new technologies and a general expansion of the fleet in order to better contend with the Tau threat.
The Second WarEdit
The Renewed Tau OffensiveEdit
The initial conflict on the Imperial frontier lasted for 7 years, with the Tau withdrawing to regroup in 2870. This respite lasted until 2871, when the newly expanded and reorganized Tau forces staged a second offensive, sweeping aside Imperial defenses in the colonies and striking deep into the heart of the Imperium in the Antioch Sector; it was estimated that over 30% of the Tau's fighting strength was sent to Antioch alone. While the Tau did land forces on some of the colony worlds, the majority were simply bombarded to ashes from space, as the Tau had learned to avoid fighting wars of attrition on relatively unimportant planets. It signaled the upping of the ante in this brutal war, and the battles fought throughout the Antioch Sector were furious, taking tens of billions of lives in that one sector alone.
The Imperium was truly desperate. Antioch was a strategically vital location, as the Constantinople Sector would be open to the Tau if it fell. However, more than 30% of the Imperial Guard and PDF forces were lost when the Tau swept through the colony sectors, while the Imperial Navy had suffered a staggering 40% loss of men and ships. Despite these losses, the Imperium was still able to marshal millions of troops in the defense of the Antioch Sector.
The Fall of AntiochEdit
Among all the battles fought in the Antioch Sector, the First Battle of Antioch in 2878 was the fiercest battle fought so far, lasting a full year. The Tau struck Antioch with great force, destroying the sector capital's orbital defenses and indiscriminately bombarding military and civilian strongpoints on the planet. Once they had finished the bombardment, they landed tens of millions of troops on the ground, determined to take one of the Imperium's key worlds at any cost. Emperor Sergius XI led the counterattack himself, only to have his flagship vaporized as the Imperial Navy fought to break the Tau blockade on Antioch.
The death of Sergius XI in combat only served to steel the Imperium's resolve even further, however. Under the leadership of Sergius' brother Sicarius, the local forces rallied, determined more than ever not to let Antioch fall to the Tau. Those citizens of Antioch who could fight were drafted into the System Defence forces and given arms to aid in the defense of their home, while those incapable of fighting or otherwise serving the war effort were evacuated; however, despite the best efforts of the Imperial Navy, the majority of evacuees were unable to make it past the Tau blockade. The planet's war manufactoriums continued to churn out war materiel even in the midst of the conflict, with small arms being issued to Imperial Guard, PDF, and System Defense infantry and vehicles being driven directly into combat as soon as they came off the production lines.
The fight on the ground was truly ferocious, with the Byzantines practiced what the Tau had described as, in their own language, a "rat war." Imperial Guard and PDF forces fought doggedly and viciously, taking full advantage of the myriad opportunities presented by the devastated urban landscape. Imperial Guard and PDF infantry lurked in the ruins, stalking their enemies and engaging them at extreme close range before disappearing back into the ruins amidst the chaos they caused. The Tau's tanks were regularly ambushed with infantry anti-tank weapons or even by Imperium tanks hiding within destroyed structures. Above all else, the Imperium was determined to make the Tau pay in blood for every inch of ground lost to them.
In the end, the Tau simply obliterated entire sections of the city-planet when it became clear that Imperial resistance was going to be insurmountable. Tens of millions of Tau soldiers had already died in the battle, and the Tau leadership was starting to lose patience. By then, most of the city-planet was a burned-out husk of its former glory. Captured civilians and military personnel were rounded up, interned in concentration camps, and sterilized in an effort to control the remnants of the population and effectively eliminate the presence of the human race in the sector.
In what was considered the most barbaric act of the Battle of Antioch, the Great Basilica, the Hagia Maria, was razed by the Tau. A video of this act was made and broadcast on hyperwave all throughout the Imperium. In the video, a Tau Ethereal stood in front of the Hagia Maria as it burned and declared, "For your failure to comply to the Greater Good, your people will be made extinct. Your cherished places of worship will be destroyed, and your God will be cast down as we have just done. You do not deserve any form of salvation." The Imperium's citizenry simply watched in horror as one of their most cherished places of worship was desecrated in the most horrifying way imaginable.
The Ascension of Heraclius XX KommenosEdit
Heraclius XX Komnenos was proclaimed Emperor after the death of his uncle, Sicarius, who had been co-Emperor. This new Emperor was truly dogged in his determination to rally the demoralized Imperial Armed Forces to fight the Tau. Heraclius XX Komnenos had been identified from a very young age as an extremely gifted psyker, and his powers were truly legendary; by the end of the war, he was known to be among the greatest psykers the galaxy had seen, a distinction he holds to this day.
When the Tau sent an ambassador demanding the absolute surrender of the Byzantine Imperium, Heraclius simply slew the ambassador where he stood and sent the dismembered corpse back to the Tau with a simple note attached:
- "Byzantium will not discuss terms while the enemy sits on Byzantine soil."
Later, in a speech to the Imperial Senate, Heraclius exhorted his countrymen to persevere:
- "Friends, Romans. Indeed we are Romans, who trace ourselves to the far-begotten Nova Terran Empire that is now but a memory. We all know that the Tau have declared us unworthy of salvation because we rejected their heretical teachings of the so-called 'Greater Good.' They have destroyed our cities, razed our planets, even gone as far as sterilized our captive population. But despair not, for the Lord God is with us! We must fight the Tau with all our soul and might! God is with us, and under the Lord's name, I call a Holy Crusade to be waged against the Tau! A Crusade, because they dared to attack God's Children! A Crusade, because the Tau have desecrated God's holy Church! A Crusade, because the Tau have dared to defile our lands and spill the blood of God's Children! I call for a Crusade, and we will not rest until the xeno heretics have been destroyed for their transgressions against God. T'au Delenda Est!"
The speech was broadcast all throughout the Imperium and was received with a standing ovation by the Senate. The fires of hatred were stoked within every human soul in the Imperium, for every citizen had at least one relative who had perished at the hands of the Tau. Priests, bishops, and Patriarchs echoed the Emperor's words, exhorting the people to take up arms or to help in any way they could to contribute to the war effort.
The Liberation of AntiochEdit
The Tau were overextended due to the grueling war on Antioch. They were forced to commit nearly 300 million troops to pacify the world and suffered horrific losses in the process. Their navy suffered losses from the brutal space combat above Antioch and from the ground based space defenses. The First Battle of Antioch had bled them quite dry, and it would take months before their navy and army could regroup for the next push. The Imperium took note of the Tau's weakness and devised a plan to exploit it. Centuries of work on genetics had granted the Imperium unrivaled expertise in genetic engineering, and it was decided that a bioweapon, an extremely contagious and lethal one, would be used against the Tau. It was tailored specifically for the Tau, and no humans would be affected.
A large portion of the surviving Imperial Navy was assembled to retake Antioch. Along with the fleet, the Adeptus Astartes would be deployed for the first time. The Astartes would be used for boarding enemy ships and taking them by force, as well as landing on the planet itself to counter and eliminate Tau troops. The Astartes would be equipped with the best weapons the Imperium could offer, and they would prove to be a force to be reckoned with in the centuries to come.
The fleet set off in 2890 with the Emperor at its head, along with his three sons: Belisarius, Rus and Aurelian. The three sons led their respective Adeptus Astartes Legions, and their names would be remembered and feared for centuries to come: the Ultramarines, the Varangian Rus, and the Anatolian Guard. The Tau did not expect a large Imperial retaliation fleet and were truly shocked by the size of the fleet that emerged from hyperspace. While most of the Tau fleet deployed to Antioch had limped back to T'au for repairs and refitting, the remaining Tau naval forces were still sizable, and they put up as good a fight as they could manage. The Imperial ships had come out of hyperspace as close as possible to Antioch and sought to envelop the Tau fleet in four directions. They drove at flank speed and forced the Tau ships to engage the Imperial ships at point blank range, negating any whatever advantages the Tau had in long-range weaponry. The battle was brutal and lasted for hours. Astartes were directly launched onto Tau ships via boarding torpedoes; once the initial shock of the boarding actions wore off, what infantry were aboard the Tau ships tried to organize some kind of resistance but were annihiliated entirely. Attempts to scuttle the Tau fleet were largely unsuccessful due to the speed with which the Astartes took the Tau ships' bridges and engineering areas, though a few ships still self-destructed.
However, instead of landing troops on the ground, the Imperium decided instead to use the first batch of anti-Tau virus bombs. The bombardment was brutal, with lances and plasma bolts unleashed upon the ground and tons of virus bombs dropped on Tau concentrations. The virus worked exactly as intended, with virtually all Tau on Antioch dead within days. A group of captured Tau were then infected with a variant of the bioweapon and loaded on ships that made kamikaze runs on Tau worlds, unleashing another virus that would afflict the Tau for a decade.
The Imperium RegroupsEdit
While the Tau spent the ensuing decade (2890-2900) attempting to fight off and recover from the virus, the Imperium spent that decade rebuilding its fleets and armies. All of the population was made to work and fight for the Imperium in any way possible, be it as a researcher or engineer in the newly-formed Adeptus Mechanicus (formerly the Science Guild) or as a soldier or naval crewman in the Imperial Armed Forces. War was now a way of life for all in the Imperium, though some were obviously allowed to stay behind and raise children. Heraclius XX Kommenos had effectively forged a massive war machine dedicated to its deadly science. Not since the wars on Old Earth or Nova Terra had anyone seen such a committed approach towards the concept of total war. Warships were constructed every day, built in the many shipyards such as the great Mars and Jupiter Yards. Millions of Imperial Guardsmen and PDF regiments were raised, along with newly forged Adeptus Astartes. The Titan was created as a super-heavy siege weapon to annihilate enemy strongholds; large numbers of these monstrosities were built and organized into their own legions. Entire worlds in Wild Space were strip-mined to provide the raw materials required to feed the Imperial war machine.
The Imperium's hyperfocus on the war effort did not mean that reconstruction efforts went neglected, however. On Antioch, amidst the devastated urban landscape, Heraclius XX raised a new Hagia Maria and declared before the new church that the Imperium would not rest until the dead were suitably avenged and the Tau destroyed. Imperial morale rose as they gazed upon the marvel of the Church, which became an eternal memorial of the blood, sweat, and tears shed in the decades-long conflict. The new Hagia Maria remains an important place of worship to this day.
The Imperium also reclaimed its colony worlds as the Tau withdrew to protect their own worlds, which were ravaged by the bioweapon that had spread viciously throughout their population. The Tau were estimated to have lost as much as 10% of their total population due to the bioweapon; those who had managed to survive the plague were left permanently crippled. The Tau were also determined to avenge their own dead, and cries to send out their own crusade against the Gue'vesa in retaliation for the bioweapon did not go unheard.
The Great CrusadeEdit
The Crusade BeginsEdit
- Main article: The Great Crusade
After the Tau spent slightly over a decade recovering from the bioweapon, they were in no more mood for mercy, and they sent a massive fleet to unleash their revenge. They struck at Ephesus, but the Imperium had learnt through its surveillance ships of the incoming fleet and had assembled a sizable force to intercept the fleet at Ephesus. The Tau were surprised to be met by an Imperial fleet that exceeded their war fleet. In what was the Fourth Battle of Ephesus, the Imperial fleet boxed in the Tau fleet and engaged the Tau fleet at close quarters. This fleet was led by Emperor Heraclius XX and his sons, who brutally obliterated the Tau fleet and left no survivors. Thus began the Great Crusade.
The Imperial Armed Forces then went on to spend the next two to three decades fighting the Tau in a war to end all wars. Brutal battles were fought above many worlds. Many worlds had their city centers subjected to brutal exterminatus, while millions of Imperial troops landed to fight and capture sector capitals to capture vital intelligence and data. The Tau were not idle either, and they had also committed their entire population to the war. These two juggernauts were engaged in a massive tug of war, and no quarter or mercy was given or received.
The Involvement of Haruhi SuzumiyaEdit
- Main article: Directorate War
The entry of the Holy Empire of Haruhi Suzumiya into the Great Crusade proved to be the tipping point of the war. Like many other human nations, the Holy Empire sympathized with the Byzantine Imperium in the opening stages of the Imperium-Tau War. However, while those human nations gradually withdrew their support for the Imperium in the face of its increasingly brutal reprisals against the Tau, only the Holy Empire stood steadfast by its ally; given its proximity to the fighting, it knew the truth of the matter. Regardless, until the Great Crusade, most Haruhiist aid to the Imperium was limited to money, raw materials, food, and medical supplies.
The Directorate changed all that, however. A despotic human government founded by exiles from other powers that the Haruhiists had subjugated in the past (the Neo-Britannians, the Zeonic Federation, and ZATO), the Directorate had a truly massive axe to grind against the Holy Empire, and it was perfectly willing to accept aid from the Tau in its anti-Haruhiist crusade. However, even with Tau military assistance, the Directorate eventually capitulated before the might of the Holy Empire; when the true extent of Tau influence in the Directorate campaign was revealed, Empress Haruhi quickly made her decision to finally commit the SOS Imperial Armed Forces to the Great Crusade. Siding with the Imperium, the Haruhiists launched large-scale assaults on the periphery of the Tau Empire, drawing off vital troops. Taking advantage of these new openings in the Tau's defenses, Imperial forces lunged deep into the core of the Tau Empire. The Tau were then desperate; ultimately, they decided to abandon worlds to the Haruhiist forces and concentrate on beating back the Imperium's advances.
Space and ground battles lasting for weeks to months were fought repeatedly as seemingly endless numbers of reinforcements were sent into the meat grinder. The Titans proved their worth in situations when Imperial forces were unable to get vital orbital support, with their mighty guns wearing down Tau defenses and allowing Imperial forces to take their objectives. When the Astartes were not launching surgical strikes against important Tau installations, they led the Imperial armies themselves. Their superhuman strength and power simply outclassed any Tau unit; even their much-vaunted battlesuits were no match for the Astartes one on one. The Haruhiists also acquitted themselves quite well in combat, making up for inferior numbers and initially inferior technology with creative tactics and sheer determination.
The Fall of T'auEdit
The final battle eventually came in the massive months-long battle for T'au. This final assault on the Tau homeworld was one of the bloodiest battles ever fought in the history of mankind. Billions of Imperial Guardsmen and PDF, hundreds of thousands of Titans and various Guard Armour, and thousands of Astartes attacked the world with two objectives: To wipe clean the Tau from the face of the galaxy, and to seize whatever databases and records they could lay their hands on. Astartes led the field armies and launched commando strikes to prevent the Tau from self-destructing their archives and power cores, while the Imperial Guard besieged Tau cities and fought brutal urban combat. Billions died during the fight for T'au, but the Imperium was ultimately victorious, with the few surviving Tau put to the sword afterwards. So ended the most brutal and bloody war the galaxy had ever seen.
After a decade in which T'au was literally picked clean of anything and everything that could be useful to the Imperium and its allies, the planet was subject to a truly brutal orbital bombardment, intended to make the Tau an example for what would happen to any xenos who dared to attack humanity in such a fashion again. After the bombardments had cleansed all life from T'au, after the very atmosphere was blown into space, after bombers had salted the very soil of the world's four continents until nothing would ever grow there again, the Emperor raised a mighty church in the largest crater of the planet the Imperium now called Tranquility, for it was very silent indeed. On the front of this basilica, the words "T'au Delenda Est" were inscribed, commemorating the words that the Emperor uttered in front of the Imperial Senate when he demanded that the Imperium commit every man, woman, and even child to the defeat of the Tau. The defeat of the Tau Empire was forever marked and celebrated annually as Victory Day, with a huge parade of the Imperium's ground war machines through the monstrous Victory Arch constructed after the defeat of the Tau.
The Apotheosis of Heraclius XX KommenosEdit
The popularity of Heraclius XX Komnenos soared to the greatest heights even at the height of the war where both sides were simply throwing ships and men into the meat grinder. The Emperor fought at the front with his troops, along with his Astartes personal guard, the Scholae Palatinae. His sons did the same, often leading the Imperial military to victory. The psychic powers of Heraclius XX became the stuff of legends, and men have claimed to have observed him even using his psychic powers to warp space-time itself. His prescience was unrivalled, and it allowed him to foresee the future, much like his forefather, Heraclius IV. His telekinetisis and skill at fire and lightning was such that few could stand in his way. At the end of the war, he was proclaimed by all Heraclius XX the Great, but such was his power and majesty that some began to suggest that he was the second coming of Christ and proclaimed him the God Emperor. This cult began to spread throughout the Orthodox Church and soon almost all recognised him as the God Emperor. His extraordinary long life further strengthened the mythos and legends surrounding him.
The Purging of the Tau AlliesEdit
After T'au had been conquered, the Imperium set about to purge the surrounding sectors of all known Tau allies. Many worlds were subjected to exterminatus, and at least one major psychic race was enslaved just so that their souls could be harvested to feed the God Emperor's ever growing power.
The Nova Atlantean Commonwealth and the Tau DiasporaEdit
Like many other human nations, the Nova Atlantean Commonwealth of Worlds was originally sympathetic to the Byzantine Imperium in its struggle against the Tau. However, as the war dragged on, the Commonwealth grew especially disgusted by the lengths the Imperium was willing to go to defeat the Tau, which its populace perceived as genocide; Commonwealth engineers were also interested in acquiring examples of Tau technology, which the Imperium had a monopoly on.
Some time in the decade preceding the Great Crusade, the Commonwealth notified the Tau that it was willing to take in refugees. In light of this, once the Great Crusade started, refugee convoys started to make their way to Commonwealth space to escape extermination at the hands of the Imperium and the Haruhiists. The Imperium's foreign ministry and the Holy Empire's Department of State both protested, but the military strength of the Commonwealth, its distance meant that any punitive expeditions by either the Imperium or the Haruhiists against the Commonwealth would give the Tau time to regroup and would most likely have unwanted political backlash in the greater galactic community. The vast majority of Tau convoys never made it past the Imperium-Haruhiist blockades, though quite a few were still able to escape to the Commonwealth. It is estimated that roughly 35 million Tau were able to reach Nova Atlantean space before the conclusion of the Great Crusade.
The Nova Atlantean Tau are mostly concentrated on the world of Hephaestus (later renamed New T'au) in the Yamato Sector, which was where the Tau population was initally allowed to settle; numerous Tau enclaves can now be found on all major worlds of the Commonwealth. This has caused some diplomatic issues with the Imperium and the Haruhiists, although the Commonwealth hopes that both powers will eventually bury the hatchet and acknowledge that the diaspora is blameless for the atrocities that its ancestors committed. To this day, diplomatic relations between the Commonwealth and the Holy Empire are still somewhat strained over the Tau issue, though trade between the two nations has yet to be hindered significantly by this; on the other hand, the Imperium flat out refuses to engage in direct diplomacy or trade with the Commonwealth, preferring to use the Haruhiists, the Solarians, or its other allies as intermediaries instead. Smaller Tau enclaves have also emerged in some of the more tolerant human nations in the last couple of centuries. The fact that the Tau population is expanding beyond the Commonwealth's borders is viewed positively by the Commonwealth, as it is hoped that the Byzantines will eventually amend their position in light of the diplomatic alienation that may result from their continued refusal to acknowledge the Tau as anything but mortal enemies to be purged at any cost.
Astropolitics of the Byzantine ImperiumEdit
The war between the Tau and the Imperium (and later the Holy Empire) was largely localized, but the scale of the mobilization of Tau and Imperium forces was significant enough to get most to stand up and take note. While most xeno races refrained from overt support, some did, but soon withdrew their support when it became clear that the Imperium would soon have the inevitable victory. No one wanted to infuriate a xenocidal power that had mobilized practically all its populace on a war path and had the potential to utterly crush anyone that challenged it.
Nevertheless, the Imperium had to make a concerted effort in the aftermath of the war to calm many nerves. Few within the UN were particularly pleased with the Imperium's complete extermination of the Tau, though there were still enough Imperium sympathizers within the UN to forestall any intervention. The fact that the Imperium still had some links to the old Byzantine Empire in Nova Terra itself played also played a role in preventing UN intervention; the Byzantine Empire's usual political manipulations ensured there was a lack of any real political cohesion to act. However, any aid provided to the Imperium at the start of the war vanished when the Imperium embarked on the Great Crusade.
Economy of the Byzantine ImperiumEdit
To say that the toll on the Imperium's economy was high would be an understatement. At the end of the war, there was no civilian economy to speak of at all. The Imperial Roman Curia had practically converted the entire civilian economy to a war economy that strictly existed to provide munitions, ships, equipment, and bodies. What was left was to requisition the raw materials to fuel the manufactoriums and the shipyards, which in turned produced the necessary weapons and ships.
Converting the economy back to a peacetime footing was no small task, compounded significantly by some 60 years of continuous war. It would take the next century or so to rebuild much of the Imperium and demobilize most of the Imperial Armed Forces. Much of the Imperial Armed Forces' equipment and ships were simply scrapped using nanorobotics to release raw material back into the civilian economy.