As Vrax and his warriors held the ramparts of the Aegis Fortress with steel and will, locked in a seemingly endless, brutal exchange with the green tide, every inch of ground they defended came at the cost of blood and explosions.
The battle took a sudden, deeply unsettling turn.
It was neither the orbital support signal they had hoped for nor the banners of another Imperial Legion breaking over the horizon.
The change came from the deepest reaches of the enemy's frenzied ocean, at the heart of the deafening cries of "WAAAGH!!!"
First came a scream shrill enough to pierce the battlefield's constant thunder.
It was not an ordinary Ork Boy's howl of pain, but a roar from something larger, filled with greater fury and shock. Vrax thought it might have come from an Ork Warboss or boss.
Like ice water thrown into boiling oil, the scream instantly sent a discordant ripple through one section of the green tide.
Then the Ork assault in that area visibly descended into chaos.
Not the chaos of a fighting retreat, but a complete breakdown into conflicting actions.
Charging mobs collided with others milling in place or even trying to retreat. Orks on the flanks suddenly attacked the "allies" who should have been advancing alongside them. Several Killa Kans lumbering forward abruptly stopped, turning their guns away from the fortress and toward other Ork units beside them.
The green tide, crude but united in its direction as though driven by a single will, suddenly became a vortex of self-destruction and mutual trampling in that one corner.
"What's happening?"
The defenders on the ramparts, Space Marines and Mortals of the Imperialis Militia alike, were drawn to the strange scene during brief lulls in the fierce exchange of fire.
Questions quickly spread through the communications channels.