Under Isolde's precise command, Brevis, this war machine, began to operate at an unprecedented speed and efficiency.
Beneath the magnificent buildings of the Uptown, rows of Vanguard soldiers assembled in orderly formation.
They were dressed in uniform blue-gray Power Armour, and the Lasgun in their hands reflected a cold light.
The Genestealer officers leading the team had sharp eyes and efficient movements, completing the formation in just ten minutes.
Beside them, the Ecclesiarchy's Sisters of Battle, clad in pure white Power Armour, wielded flamethrowers and Chainsword.
They chanted Emperor hymns aloud, their fervent faith seemingly enveloping them in a faint golden light.
The private armies of the nobles, however, were of varying quality.
Some nobles were accompanied by well-equipped family guards, Power Armour and weapons were all custom-made.
Some only managed to gather a few hundred servants carrying old Lasgun, who dawdled along behind the procession.
But whether they liked it or not, faced with the deterrent power of the Vanguard and the threat of Chaos, no one dared to actually desert their post.
The Northern Allied Army, like an iron torrent, surged towards the upper entrance of the Midtown along the Hive City Expressway.
In the dark and damp Lower City, the scene was even more chaotic and turbulent.
Countless ragged civilians poured out of the slums.
They were carrying all sorts of weapons.
A salvaged Lasgun, a razor-sharpened steel pipe machete, or even just a heavy alloy plate in hand.
The leaders of the Scavengers' Alliance walked at the front, followed by their respective subordinates.
Gang members, cigarettes dangling from their lips, swore and squeezed into the crowd.
Even the elderly and children who usually huddle in corners, barely surviving, carried ammunition boxes and followed behind the group.
For them, a month's worth of food is their only hope for survival.
They surged like a tide towards the lower entrance of the middle Lower City, following the network of pipes and alleyways of the Midtown.
Their numbers were more than ten times those of the Northern Route Allied Army, and their equipment was pitifully rudimentary, but their fearless spirit was in no way inferior to that of a regular army.
Meanwhile, above Brevis orbit.
The Gemstone of the Tithe Fleet had adjusted its hull position, and the Macro-cannon array on its broadside slowly rotated, its muzzles aimed at the Chaos- occupied territory of Midtown.
Dominic stood on the bridge, his red hair concealing a serious face.
He never expected that, not long after arriving in Brevis, he would first encounter the unfathomable power of the Orks warlords, and now he would face the arrival of the Thousand Sons.
"Calibrate firing parameters, avoid the normal areas of Midtown, and prioritize attacking the Chaos defenses," Dominic ordered in a deep voice.
"First salvo, prepare, fire!"
"Boom! Boom! Boom!"
The Gemstone's fifty-two Macro-cannon roared first, leading the Tithe Fleet in bombarding the target.
The explosive bomb, weighing several tons and trailing a long plume of flame, tore through the atmosphere and hurtled toward the Chaos position in the Midtown.
Huge explosions rang out one after another on the edge of the Midtown, and towering flames illuminated half the sky.
The sturdy factory walls crumbled like paper under the Macro-cannon, and the makeshift fortifications were instantly razed to the ground.
The Chaos Cultist hiding behind didn't even have time to scream before they were blasted into a cloud of blood mist.
The support of orbital firepower officially kicked off the decisive battle.
"Charge! For the Emperor!"
The vanguard of the Northern Route Allied Forces launched the first attack.
The Vanguard soldiers advanced in skirmish lines, their Lasgun firing in unison to create a dense barrage of fire, suppressing the Chaos Cultist on the front lines and preventing them from raising their heads.
The Sisters of Battle, like white blades, tore through the enemy's defenses, their Chainsword spinning at high speed, slaying the mutated monsters that pounced on them one by one.
But soon, they encountered a real rival.
Several Norsak wizards dressed in black robes emerged from behind the fortifications.
Their eyes gleamed with a ghostly light of Psychic Power, and with a gentle wave of their scepters, several Psychic Power missiles whistled out and crashed into the Imperial Army's positions.
Several Vanguard soldiers were unable to dodge in time and were struck by Psychic Power. Their bodies instantly twisted and deformed, turning into a pool of pus amidst screams of agony.
"A wizard! Chaos Sorcerer!"
Amid the soldiers' gasps of surprise, the Norsak wizards began their chanting.
Purple Psychic Power flames rose from their palms, then transformed into rain of fire that fell from the sky, covering a large area of the attack zone.
The searing pain caused the soldiers to scream in agony, and their formation immediately fell into chaos.
"Hold the formation! Heavy Bolter squads suppress the enemy! Assault teams flank!"
The Vanguard officers roared and quickly adjusted their tactics.
The Heavy Bolter roared incessantly, unleashing a hail of bullets at the Nosak wizards.
However, this was neutralized by the Chaos Spawn and defensive fortifications in front of them.
The battlefield on the southern route was equally brutal.
The civilian militias in the Lower City surged forward like a tide, only to be battered and bruised at the Chaos Fortress.
The Cultists operated modified heavy machine guns, firing wildly at the charging crowd.
The civilians at the forefront fell in droves, their blood flowing down the street slopes and forming red streams.
But no one backed down.
Those behind trampled over the corpses of those in front, still charging forward madly.
They knew that retreating meant certain death, while charging forward offered a glimmer of hope.
In the chaotic battlefield, the scavengers, relying on their familiarity with the Hive City, constantly outflanked and attacked from the side ventilation ducts and abandoned passages, using homemade explosive charges to destroy enemy firing positions.
Gang members, in groups of three or five, would fire and move on, engaging in brutal street battles with the Chaos Cultist in the most unsavory way possible.
Every street, every factory, and every section of pipeline in Midtown became a battlefield.
Under the command of the Thousand Sons Sorcerer, the Supreme Thrallband carried out its defenses methodically, relying on the existing heavy industrial buildings and hastily constructed fortifications in the Midtown.
The combined use of Psychic Power attacks and heavy firepower repelled the Imperial Army's charges time and again.
They were like a nail, firmly nailed to the land of the Midtown, unmoved no matter how fierce the Imperium artillery fire was.
The Warp Domain is still slowly expanding, and the Chaos power within it is becoming increasingly concentrated.