As they drew closer to the front, the endless roars of monsters grew deafening until Solant's antennae were vibrating from the force of it. Her general's eye crackled into life the closer they got to the field, her intuition and mutations blending together to give her an almost supernatural sense for the battlefield.
The ants were tired, which was to be expected. They moved sluggishly, taking more damage than they should, and attacked without sharpness, inflicting less punishment on the enemy than they were capable of.
This was a compounding problem that led to more damage being taken and more ground lost as the shifts dragged on. Of course, the Colony could simply rotate the ants more often, but that introduced more problems than it solved. Logistically, shifting hundreds of thousands of ants around was a nightmare already, doing it more often would just compound the issue.
Despite the huge numbers of ants inside the nest, there was far more fighting taking place than any of the leadership had expected. The tunnels beneath the nest were absurdly extensive, as if a tunnel network the size of the entire first stratum had been bolted onto the bottom of the mountain. The absurd number and size of monsters appearing out of the waters had also taken the Colony by surprise, drawing their resources even thinner.
Solant would need her current group of troops to hold at the front for four hours before they would be relieved by the next shift. In another two hours' time, she would arrange for the incoming ants to go through the same drills the current group had under the leadership of her sisters, since she wouldn't leave the front.
"Get ready to charge," she announced calmly as the massive soldiers and scouts clacked their mandibles eagerly.
She watched the fighting ahead with her intense gaze, waiting for the perfect moment.
The monsters surged, the ants reared back, and she had found the timing.
"Charge," she said.
Her troops rushed forward, covering half of the tunnel surface as they ran. The thousands of ants already fighting saw their approach and the general in charge coordinated the retreat.
"Acid and magic blast, go!" she roared and the exhausted troops gave everything they had left to beat back the monsters and give them the separation they needed to retreat.
It was a delicate moment, and Solant watched carefully as the current shift began to compress their formation and fall back. An almost bizarre sight, like two fluids moving in opposite directions through a single pipe, took place as the retreating ants crushed into one side flowed back to safety while Solant and her fresh army pushed forward, towards the enemy.
"Snap into place and brace," she instructed the soldiers in front and they knew exactly what to do.
Right at the front of the formation, Solant had picked the exact moment the retreating line of soldiers had passed them and had her own reform the line, covering the entire ring of the tunnel's surface. The soldiers rushed into position and braced themselves, ready to receive the deadly charge of the monsters ahead.
That charge came swift and brutal. Larger and stronger than what the Colony had fought higher in the Dungeon, the beasts of the fourth were fewer in number, but much harder to deal with.
An enormous, elongated caterpillar squirmed towards them, acid rolling from its body and sizzling on the rocks below. The soldiers received its charge, ignoring the pain as the burning liquid splashed on their carapace. With their enormous heads and reinforced mandibles, they latched onto the beast, halting its momentum and tearing at its soft flesh as the rest of the formation took shape behind them.
"Hold," Solant informed them, "ten seconds."
It was important not to rush, despite the danger to the soldiers on the front. If the rest of the troops were sloppily arranged and asked to engage before they were ready, it could upset the flow of battle for the next several minutes. She would gladly allow an extra few seconds to ensure that didn't happen.
"Step back on the left."
"Push forward."
"You're not in line, watch your flanks."
A steady flow of calm commands rolled from her pheromone gland to the struggling soldiers, helping them to hold the line and avoid the worst of the acid until, finally, the defensive position had been established.
"Fire on my command," Solant ordered, waiting a beat, then, "fire."
Scout acid and magic blasts slammed into the caterpillar's face, sending the monster reeling back.
"Again on my command… fire."
The moment it regained its balance, the beast was hit again. It screeched in fury and retreated slightly. An opening.
"Advance ten metres," Solant snapped.
Already an opportunity to move the line forward had appeared; she wouldn't say no. Ground taken now could be freely given later, when her troops were more fatigued.
Moving as one entity, the entire force of thousands of ants surged forward ten metres and reengaged the caterpillar, seizing on its weakness and putting it down.
With a moment of respite, the beast was dragged to the back of the formation. Valuable Biomass that would help heal and refuel the army.
The first minute had passed.
"Rotate," Solant ordered.
Step, step, dash.
Just like that, the frontline troops swapped over. The first wave of soldiers moved to the back of the line where they were fed and received medical care while a fresh group replaced them. The same occurred behind them, as mages and scouts repeated the move, their accompanying generals holding position at the front of the formation.
Just in time. More monsters were coming.