Arbitrators of the Adeptus Arbites, leading small squads of Planetary Defense Forces, patrolled the streets of the Hive. All civilians had been ordered to remain in their hab-blocks under penalty of death.
The swarm had already reached the outer perimeter. Even within the spire, the rhythmic thunder of heavy ordnance echoed from the outer walls several kilometers away. Batteries of Basilisk artillery had been pre-positioned in the rear of the ramparts, their crews working with a frantic, mechanical desperation.
From common loaders to Regimental Colonels, almost every man on the artillery line wore bandages. Despite working in two-shift rotations, the endless, repetitive cycle of loading and firing had left them numb, mere extensions of the guns they served.
Outside the walls, the swarm was so dense that the Basilisks required no targeting data. Every shell fired into the distance was guaranteed to find meat.
Ever since the Imperial Navy elements stationed here had been annihilated in orbit, mycetic spores had fallen like a black rain across the world. As a Civilized World, Aurelis possessed vast continents, deep oceans, and a temperate climate, all of which were perfect for the Great Devourer. The oceans were rich in biomass, and the continents teemed with the diverse fauna preserved by humanity.
The planet's three Hives held a combined population of over five billion souls. With the Tyranid arrival, the world had been ignited into a nightmare. To the swarm, this much biomass was nothing less than a divine feast.
One Terran hour ago, the Hive on the northern continent had gone silent. Nearly a billion Imperial citizens, ten million PDF soldiers, and three million Astra Militarum troops deployed from orbit had vanished from the vox-caster net. No one knew what had happened there, and no one had the luxury to care.
Hundreds of millions of xenos were scoured across the planetary surface. Even though the Imperial fleet had managed to dump tens of millions of Astra Militarum troops, originally meant for other war zones, onto the surface before being destroyed, it was merely a stay of execution.
The Tyranid fleet had maintained a sustained orbital bombardment until the Hives' void shields collapsed. Now, to maximize biomass recovery, the swarm attacked from the ground. Gargoyles choked the skies; Mawlocs attempted to burrow beneath the Hive's foundations. Termagants and Hormagaunts swarmed the walls, stacking their own dead to create ramps of chitin and bone. It was only a matter of time before the ramparts were overtopped by a tide of corpses.
To prevent the swarm from breaking in for their feast, the Astra Militarum fought for every meter of the wall. Leman Russ and Macharius tanks attempted to emulate the arcing fire of the Basilisks, lobbing shells over the battlements to detonate within the roiling mass of the swarm.
The gargantuan walls, stretching for hundreds of kilometers, were under assault from every direction. Without void shields, the Tyranids' acidic ichor, bio-plasma, and living ammunition rained down upon the outer districts. The Hive's defense batteries fired without ceasing, their barrels glowing dull red.
The industrial zones outside the walls had already fallen. All ammunition now depended on a handful of weapon factories in the Lower Hive. While other civilians were confined, the workers here were ordered to labor until they collapsed. Tech-Priests of the Adeptus Mechanicus oversaw every shift, chanting litanies to ensure the Machine Spirits of the production lines did not falter under the strain.
Ammunition stockpiles were vanishing like water in a desert. Yet the swarm remained inexorable. The oceans had become massive spawning pools. Once the Tyranids finished digesting the billion souls from the northern Hive, their numbers would become truly astronomical.
Inside the Hive's Choir Chamber, several Astropaths who had lapsed into madness had already been executed. Every telepath who touched the Warp felt only the horrific, cold hunger of the Shadow. The phantom of death haunted every psyker, as dread threatened to drown these "lucky" few in a sea of psychic turmoil.
CRACK-BOOM!
With a deafening roar and a gout of bio-alchemical fire, a section of the Hive wall collapsed. A leading Mawloc had successfully undermined the foundations of the outer rampart. Under the weight of sustained fire and the shift in the earth, the wall gave way, crushing the PDF crews and their Hydra flak tanks into the dirt.
As the first breach opened, the structural failure cascaded. Countless Hormagaunts, shielded by spore clouds, began to charge over the rubble. Termagants followed, firing as they ran, with Carnifexes and Tyranid Warriors trailing in their wake.
When the massive silhouette of a Hive Tyrant scaled the rubble of the breach and let out a piercing, synaptic shriek, the general assault began. The Tyranid swarm poured through the gaps like a dam bursting.
Between the outer wall and the Hive proper lay a vast expanse of crisscrossing trenches. Millions of troops along this two-kilometer-deep "kill zone" braced themselves to intercept the breach. Desperate Imperial forces had mined the trench lines with powerful melta-charges. Should a line fall, the mines would incinerate everything in the trench before the swarm could advance.
It was a war of no return. If they failed, the swarm would consume all. The sky was choked with bio-ships; there was no escape.
Driven by the fatalism of the damned, the Imperial defenders fought with terrifying ferocity. The roar of cannons and the hum of lasguns were deafening, a cacophony of human screams and xenos shrieks.
But amidst the swirl of bio-rays and las-bolts, several massive blue streaks of light, accompanied by hundreds of smaller pinpricks, tore through the atmosphere toward the surface.
A few soldiers noticed the falling stars, but they held no hope. The wreckage of the Imperial fleet was clearly visible in the sky. Whatever was coming down, they assumed it wasn't Imperial reinforcements.
BOOM!
Several colossal globes of blue energy slammed into the earth outside the walls, incinerating xenos and soil alike within a radius of kilometers. The erupting energy shockwaves sent the following waves of the swarm tumbling.
Then, scores of massive, unknown combat craft descended from the heavens, their weapons sweeping the ground clear. Huge metallic cargo structures, after a final deceleration burn, slammed directly into the scorched, superheated earth.