Within Segmentum Tempestus, at the edge of the Desolate Sector.
A vast fleet composed of the Imperial Navy's frontline battleships, Strike Cruisers, and frigates, along with dozens of standard Men of Iron fleets, stood ready for battle.
Behind the fleets lay the fortress worlds modified by the Men of Iron, holding a billion pieces of "bait."
They needed to inflict as much damage as possible on the swarm before it reached those worlds, then use the fortress worlds to sustain their resistance for as long as possible.
But unlike any previous war, this one was different.
In this war, they had been explicitly ordered that retreat was permitted.
Before the battle spiraled out of control or they faced catastrophic losses, they were allowed to abandon the worlds behind them and withdraw to the second defensive line.
The Men of Iron would evacuate the comrades left on those worlds.
Even so, the atmosphere on the bridge of every naval vessel was almost unbearably tense.
Beyond the vast observation windows, a writhing, expanding shadow was swallowing the stars.
It was the vanguard of the Tyranid Swarm. Having just broken through the natural hazards and automated defense platforms, it lunged toward the flesh that drew it onward, driven by enraged frenzy and eternal hunger.
"All ships! Hold formation! Void Shields to maximum power! All weapon batteries, fire at will!"
The admiral's orders spread across the fleet through the communications network, his voice slightly hoarse with tension.
The next second, the void ignited.
The Imperial Navy's Macro-cannons unleashed deafening roars, their enormous solid shells trailing blazing wakes as they slammed into the swarm like the thunder god's hammer.
The searing beams fired by the Lance Batteries cut precisely through the immense bodies of the Bio-ships like swords of judgment.
Plasma Turrets spat devastating balls