A rubber tube connected to a blower, with the switch turned on, delivered gas from a high-pressure cylinder into the underground cave. These gases varied in color and properties, but they all had one thing in common: they were poisonous! Not only could zombies not survive in these gases, but even elephants wouldn't last.
Outside the cave, everyone wore gas masks. If any gas leaked out, it would be bad to accidentally harm their own people. These gases were no joke; a single whiff could be life-threatening.
Among the gases injected into the cave, the most lethal were cyanide compounds, followed by sulfides and chlorides. As soon as zombies inhaled these gases, they would foam at the mouth and die. The zombies in the cave had all entered a state of hibernation, consuming the least amount of energy. They could still hold on for two months.
Clearly, the zombies had not anticipated that Yanjing would launch an offensive during the heavy snowfall.
Tens of thousands of soldiers in the southern region had occupied tens of square kilometers. This area was insufficient to cover all the underground caves in the south, but it was still a significant portion. If today's operation was successful, it would only take more than ten days to eliminate all the zombies in the southern region.
Xiao Sheng, along with the special forces, stood at a distance, observing the events on the battlefield. He suddenly exclaimed, "This method is quite good. It even saves the trouble of cremating the zombie corpses. Just block the cave entrance, and you can erect tombstones for these zombies. If only we had used this method earlier."
Zombies hid underground, and under normal circumstances, human weapons had little effect on them. Moreover, the thick earth could insulate against the severe cold, so zombies hiding underground would not freeze to death due to low temperatures.
However, under the attack of toxic gas, the zombies were completely defenseless and could only be killed one by one. The underground caves they had previously dug had now become their burial grounds. As long as all the cave entrances were sealed, these zombies would be buried alive.
The toxic gases injected into the underground caves were all denser than air. This ensured that the toxic gases would not dissipate quickly. During this period, no matter how many zombies entered the first layer of the cave, the situation could not be changed, because even mutated zombies could not withstand the attack of the toxic gas.
Furthermore, if the passage from the first layer to the second layer was not sealed in time, the toxic gas could sink further, posing a threat to the zombies in the second and third layers. The zombies in the first layer were insignificant, but the second and third layers housed many mutated zombies and zombie kings, which were the core strength. Any damage to them would be irreversible.
The battle in the southern region finally saw a change within half an hour. The zombie kings could feel the number of zombies they controlled constantly decreasing. Although all the casualties were ordinary zombies, at this rate, the zombies in the southern region would surely be severely depleted in a short period!
Under normal circumstances, zombie kings were indifferent to the life and death of ordinary zombies. The loss of a hundred thousand or so was nothing. However, if more than half were lost, the zombie horde's scale would inevitably shrink. In such a situation, even the survival of the zombie kings would be affected! Moreover, with toxic gas being pumped into the ground, tens of thousands of zombies were being killed every minute. Such a rapid rate of attrition was unbearable even for the zombie kings.
Therefore, the zombie kings in the southern region immediately dispatched mutated zombies to investigate the situation. Both speed-type and strength-type zombies were sent out to scout. Why were the ordinary zombies in the first layer continuously dying? What was happening? Were humans starting to attack the underground caves?
The zombie kings initially thought that it would be easy for the speed-type and strength-type zombies to scout the first layer of the cave. Even if they couldn't defeat the human army, they could at least safely return underground to report the situation. However, this was not the case. The mutated zombies sent to scout never returned, which was a perfect illustration of the saying: "Like a meat bun thrown to a dog, there is no return."
The zombie kings in the southern region sensed that something was wrong. They quickly gathered in the third layer underground to discuss the current crisis. Fear began to grip their hearts. They hid in the deepest parts of the earth precisely because they feared the threat posed by human technology. Now, with the continuous killing of ordinary zombies, they were under immense pressure.
"In the first layer of the cave, the passages are filled with toxic gas! This is information I obtained at the cost of over thirty mutated zombies' lives. Humans have begun to counterattack us!" a zombie king with a scar on his forehead stated first.
This intelligence was extremely important. The zombie kings had assumed that with the arrival of winter, both sides would pause the war, as no one could ignore the impact of low temperatures. Especially in the north, winter temperatures often dropped to minus ten degrees Celsius. This was essentially a natural freezer; who would be active in such conditions?
However, reality dealt them a harsh blow. Humans had indeed attacked, launching an offensive in the freezing weather and injecting toxic gas underground, causing massive casualties to the zombie side.
The zombie kings were unwilling to wait for death. They immediately stood up and said, "What's there to discuss? Wake up the hibernating zombies, and all of them charge out to kill all these humans who are releasing toxic gas! Let them all die, and then see if they dare to have any ideas about us!"
"Yes, kill them all. It would be best if we could heavily cripple the human army, making it easier for us to attack in the spring!"
"Killing one to warn a hundred is the most appropriate choice. Offense is the best defense!"
"Perhaps we can even wipe out these humans and force them to negotiate with us. Then, wouldn't our objective be achieved?"
There were over fifty zombie kings in the southern region. These big-headed zombies were crammed into a small room, making the stone chamber extremely crowded. These zombie kings were chattering about their next course of action, with almost all of them advocating for a charge to kill all the humans above, to prevent further damage.
However, at this moment, one zombie king raised a question: "Then, tell me, how will so many zombies keep warm?"
This question immediately caused all the zombie kings to cease their excited conversation. They had overlooked a problem: the threat of severe cold. As early as the first snowfall around Yanjing, the zombie kings had to retreat reluctantly. Even so, more than a million ordinary zombies had frozen to death in the snow. While attacking was simple now, what would happen after they charged out?
Low temperature was an unavoidable predicament. All living beings were affected by temperature, and zombies possessed all the weaknesses of humans. The heavy snowfall outside was not just for show; this snow could freeze zombies to death.
The zombie virus outbreak occurred in the summer. All the zombies wore dirty clothes from summer. Many zombies' clothes were torn when they passed through forests, leaving them naked. It was wishful thinking to expect them to withstand the cold in such attire.
Therefore, as long as the zombies dared to leave the underground, it would not be humans who killed them, but the ubiquitous ice and snow!
For a moment, the stone chamber became quiet. Due to the cold, the zombie kings could not dispatch ordinary zombies to fight. If they left the underground, the number of ordinary zombies would decrease, while the threat posed by humans would not disappear.
"These despicable and shameless humans! They are using such base tactics, attacking precisely when we have no thermal gear. Shamelessness! Shamelessness!" At this moment, a zombie king began to curse loudly. In his opinion, the humans' methods were too despicable, attacking during a snowstorm, which was practically killing him!
The other zombie kings also condemned the humans' despicable actions: "Utterly shameless! Why take advantage of our predicament? If you have the guts, come down to the cave and fight us fair and square, hand-to-hand. Then we can bury you with sheer numbers of zombies!"
"Exactly! These humans should wait until spring, when the temperature rises, and we awaken the hibernating zombies, and then re-encircle Yanjing. That's when they should attack! Honestly, they claim to be righteous, but their actions show no sign of righteousness whatsoever!"
Many zombie kings began to condemn the humans' actions, but while they vented their anger, they could not come up with any solutions.
Scarred Zombie King saw this scene and thought to himself, "Are these guys reborn as Duke Huan of Song? Battlefield situations are constantly changing. Who wants to fight you honorably? Am I really stuck with a bunch of idiots as teammates?"
Finally, Scarred Zombie King stepped forward and said in a deep voice, "We cannot dictate how the enemy develops their tactics. We can only charge out now and fight these people. Ordinary zombies will indeed freeze to death outside, but mutated zombies are different. Mutated zombies have far superior physical fitness compared to ordinary zombies. If we mobilize the mutated zombies we have, we can still launch a surprise attack on the human army. Moreover, in heavy snowfall, mutated zombies are easier to conceal!"
Scarred Zombie King proposed the only solution available: to dispatch the most elite mutated zombies to fight. There were nearly twenty thousand mutated zombies remaining in the southern region. If such a large number of elites were deployed, victory would surely be achieved.
Unfortunately, as soon as this suggestion was made, it was immediately opposed by the other zombie kings. Zombie kings were not selfless individuals. Even if all the ordinary zombies were wiped out, it would not fundamentally harm them, as there were still many ordinary zombies in the south. However, mutated zombies were not so easily obtained. Mutated zombies were the bodyguards of the zombie kings. If the surprise attack failed and they were all killed, wouldn't they be left without bodyguards?
If ordinary zombies were gone, they could find more in the south. But if all the mutated zombies were killed, the zombie kings would be truly vulnerable. After much consideration, none of the zombie kings were willing to dispatch mutated zombies for such a dangerous mission.
Seeing the true colors of everyone, Scarred Zombie King sneered, "You guys are too short-sighted, aren't you? Do you know what will happen if this continues? Not only will the zombies in the first layer be wiped out, but the zombies in the second layer will also be killed sooner or later. In the end, everyone will be trapped underground. With planes constantly monitoring from above, where will you run? If you can't even figure this out, you deserve to be in this situation!"
"You say that so easily. If all our bodyguards are dead, we'll truly be at the mercy of others. We won't even have a chance to escape then!"
Immediately, a zombie king retorted.
The two sides argued endlessly, and finally, they reached a compromise. Scarred Zombie King's plan had to be implemented: dispatch mutated zombies to attack humans, preventing human toxic gas from continuing to enter the ground. However, not all mutated zombies could be sent out. This attack plan would only involve five thousand mutated zombies, which was one-fourth of the total.
Scarred Zombie King felt helpless. How could they achieve ultimate victory by being with these vermin?
Digging zombies excavated new tunnels from the third layer, bypassing the toxic gas-filled first layer and heading directly for the ground targets.
In the first layer of tunnels, there were no living creatures left in any of the gas-filled passages. The denser toxic gas continued to spread outwards, and the passage between the first and second layers had been sealed to prevent the toxic gas from entering the second layer and causing greater casualties.
On the surface, Qin Kewei stood on the bare ground, her hands touching the yellow earth, sensing intently. Suddenly, she detected an anomaly and quickly took out her walkie-talkie: "Report, zombies have begun their attack. Please be aware of the ground and beware of zombie attacks!"
Cheng Ke received this message, and his heart sank. The real test had arrived. He quickly issued instructions: "All personnel prepare for battle. Prioritize the protection of technical personnel, followed by the gas delivery devices. Do not remove your gas masks during this period!"
Actually, the method of using toxic gas to attack zombies hiding underground had been proposed long ago. However, no one knew the underground conditions at the time, so it could not be used. The effectiveness could not be estimated, and the production of these gases was also resource-intensive and not to be used lightly.
It was not until Shen Feng emerged from underground that sufficient information was brought back. The headquarters then made the decision to use toxic gas to attack and first kill all the ordinary zombies!