After losing the suppressive fire support of the point-defense cannons, the pressure on the various defensive sectors around the fortress suddenly increased dramatically. The tyranid Swarm, under the unified command of the Hive Mind, quickly adjusted its tactics.
It gathered a large number of Exterminators, heavily armored and resembling living battering rams, and chose the relatively weak eastern flank to launch a concentrated, devastating breakthrough.
Led by the Exterminators, these "iron-headed brutes" used their flesh, blood, and bony ramming horns, combined with the ranged attacks of other tyranid Swarm, to forcibly breach the fortress' outer wall, which was cast from thick alloy.
Accompanied by the screeching of twisting metal and the cracking of concrete, a huge gap appeared.
Seeing that they had finally torn open this hard shell, the tyranid Swarm on the ground naturally surged in like a breaking tide, letting out earth-shattering roars. At the same time, the gargoyles circling in the sky collectively dived down, with a few lucky ones breaking through the still-retaliating net of fire.
The Helldivers on the front lines had to start being wary of deadly strikes from the sky, and the entire battle quickly devolved into the most bloody and brutal phase of close-quarters combat.
Seeing this fortress, which had consumed vast resources and time to build, being breached so quickly by these xenos, Wick's heart tightened.
But this situation seemed to have been anticipated by the others. They had never hoped to build a so-called "impenetrable shell" to completely keep the tyranid out. No one could do such a thing, at least not the Helldivers unit stationed here.
The previous expansion of this island was precisely to have sufficient combat depth.
Dimitry looked at the continuously expanding red area on the tactical projection and calmly ordered, "Release the toxic gas!"
At this command, the pre-installed pipes and nozzles within the fortress instantly activated. A large volume of dark green toxic mist was rapidly released, and it expanded its coverage to the entire fortress area at a visible speed.
Dimitry turned to Wick and kindly reminded him, "Tallen, have your Skitarii Guard temporarily retreat into the internal sealed spaces."
Wick shook his head and said in a deep voice, "No need. Since the Astra Militarum, as mortals, have not retreated, there is even less reason for the mechanically modified Skitarii Guard to retreat."
But the following scene made Wick immediately understand why Dimitry had said that.
These toxic gases were clearly very carefully formulated. Wherever they passed, all organic matter and moisture they touched would instantly begin to combust violently, producing more of the same toxic gas, forming a terrifying chain reaction.
As for solid metal, under the coverage of these toxic gases, a protective passivation layer quickly appeared on its surface, but this passivation layer was then corroded away by the toxic gas in the next second. This cycle repeated, and even thick alloy walls became increasingly weak and fragile at an astonishing rate.
No wonder they wanted their Skitarii Guard to retreat! Wick suddenly understood, but then a question followed: "Those mortal soldiers… how do they withstand this toxic gas?"
"They will perish with the enemy in the toxic gas," Dimitry replied, stating a fact.
The effect of the toxic gas was very significant. Although the carapaces of the Helldivers were also rapidly destroyed in the toxic mist, their exposed skin, respiratory tracts, and eyeballs immediately suffered severe chemical burns, making it difficult for them to see and breathe.
However, under the suppression of potent agents injected into their bodies, they successfully avoided systemic toxic reactions, and the degree of tissue necrosis was still within an acceptable range.
The tyranid swarm, however, had no such preparations. Their sensory organs were completely destroyed the moment they came into contact with the toxic gas, and their previously efficient and well-coordinated concentrated breakthrough fell into a certain degree of chaos. Some Hormagaunts, Warrior Swarms, and Exterminators lost their sense of direction, began to charge in the wrong direction, and even attacked friendly units.
The gargoyles that had broken through the net of fire and dived down also lost their balance, screaming and tumbling in the air, unable to control their flight paths.
In this situation, the Helldivers, with impaired vision and breathing, immediately launched a large-scale counter-charge. The entire area was a scene of flying flesh and blood under the clash of blades and claws. Although they could not push back the swarm, they managed to stabilize the collapsing front line through this tragic method.
On the surface, this seemed worth celebrating, as the battlefield had devolved into a bloody war of attrition, which was the Helldivers' specialty. But in reality, it was a pure trap. The Helldivers could not prevent the tyranid Swarm from dragging all the flesh and blood on the battlefield—both their own and human—back for recycling.
And the deaths of the Helldivers themselves were still generating new biomass for the enemy. As long as the tyranid's biomass replenishment did not become negative, this battle could never be won.
So, Dimitry issued a second order: "Deploy the acid."
The prepared artillery units in the rear immediately carried out the order. A large amount of transparent liquid was launched, covering the entire engagement area like a downpour. But this time, the effect was not ideal: the Helldivers who came into contact with this potent acid were dissolved down to their bones within practically ten seconds.
The tyranid, however, only emitted plumes of white smoke in the acid rain and roared in pain a few times, which only further ignited their ferocity.
The sudden decrease in friendly combat personnel caused the recently stabilized front line to retreat a few more steps, only stabilizing again when subsequent Helldivers arrived on the battlefield.
"Ha!" Boni looked at the scene and said without ceremony, "I told you, this was a bad idea! The tyranids can already spit acid from their mouths, how could they not have corresponding resistance!"
Leonid immediately retorted, "But at least they can't recycle our soldiers' biomass!"
Dimitry raised his hand, interrupting the two who were about to start another argument: "These acids are indeed useful, but it now seems their primary function is to dissolve biomass. We need to come up with a new way to use them; at least we can't just throw them directly onto our front-line warriors who are fighting the enemy."
Just then, Wick, who had been silently observing, suddenly spoke: "We don't need to use it to kill living enemies, but to clear the 'battlefield' behind the front line."
This simple yet effective suggestion made the others pause simultaneously, then their eyes lit up.
Wick continued, "Have the artillery units launch a saturation bombardment on the positions we just lost, which are now piled high with corpses. This will both completely dissolve the bodies, preventing the tyranid from recycling them, and turn the land into an acid swamp, delaying the advance of their subsequent forces."
"Good idea!" Joker immediately grabbed the communicator and issued new instructions.
Soon, the artillery fire from the rear accurately bypassed the front line and landed in the area between the first and second defense lines, which had just been overwhelmed by the swarm.
Pungent white smoke rose into the sky, and the remnants of the Helldivers, under the coverage of the strong acid, dissolved at a visible rate, turning into a sizzling, unrecyclable sludge.