He made this decision to play it safe. His reason for doing so is the same reason why he didn't immediately join in the assault.
Kelvin didn't fight the vampires personally. The first thing he did was to assess the situation.
That was his hob as the leader. He couldn't get carried away, so he made sure that everything was in other before he joined the battle.
Even then, he too used a gun together with the others and mowed down the vampires without standing out.
The soldiers were making a lot of progress with their mission. Most of the credit was due to the special bullets that they were using.
Ordinary bullets won't harm vampires much. At most, the bullet will cause a superficial injury that can be healed in an instant.
No matter the physical damage that a normal bullet does to a vampire, even if that bullet severs the head of the vampire from its body, the injury will still be superficial.
But the bullet that they are using is radioactive and highly poisonous to vampires. Any injury that it causes to the vampire becomes an infected injury that is not only difficult to heal but can also kill the vampire if given enough time.
The 80 soldiers first marched backward down to the natural access point of the target. This place was the mouth.
They cleared the way of vampires to make sure that this portion of the target was safe. As they were doing so, they were also destroying the internal organs of the wayfarer to make sure that it doesn't awaken.
As they moved along the space of the shell, they dropped the chemical lamps to illuminate the space and white noise machines to pollute the space with noise.
These chemical lamps produced light based on a chemical reaction between two reagents sealed in a transparent tube. There was no electricity involved, so they weren't affected by the active magnetic field of the planet.
The white noise machines were materials produced in Umbra. They were small boxes with iron fillings in them.
The iron fillings in the box oscillate because of the magnetic field. This causes them to smash into each other. The friction creates sounds.
Since they were powered by the unique situation of the planet itself, they weren't in any danger of being disrupted. Instead, the more active the magnetic field became, the louder the boxes became.
The sound the boxes produce is harmless to humans. But to vampires, the sounds might as well be pounding their heads. It was slow torture.
The white noise machines and the chemical lamps created a zone of sensory deprivation. This sensory deprivation wasn't silence or the lack of sensation. It was an overload of sensory information that was so irritating, the vampires felt like clawing their eyes and ears out.
Just placing these two things on the ground alone blocked the vampires from advancing on them. The vampires could overcome the irritation to attack them, but doing so put them in a disadvantageous, dangerous, and unpleasant situation.
So the trail of chemical lamps and white noise formed a natural barricade against the advancement of the vampires. It was as if a river was placed between ants and sugar. Even though there was something sweet to devour on the other side, it is unlikely that they would survive crossing the river to reach the sugar.
After clearing the tunnel all the way to the back, the soldiers returned the way they had come. They reached the hole in the shell they had used to enter and then went out of it to replenish their supplies.
They got more ammunition, grenades, flashbangs, white noise boxes, and chemical lamps. Then they returned to the shell to resume their clean sweep of it.
Their tactic was simple and straightforward. First they pave the way with sensory overload. They throw the chemical lamp and the noise box ahead of them. Then they advance.
Each step forward that they took was taken on ground that had been littered with chemical lamps and white noise boxes. This way, they always had the advantage in the confrontation.
This way, the vampires were forced to give ground to the soldiers. The vampires were pushed back again and again. They had only two choices; they could either die in the shell at the hands of the Yggdrasil army or die outside of the shell at the hands of the wayfarer.
Either way, they were doomed. They had no chance to turn the tide of battle in their favor. At this rate, they were all going to die.
Kelvin, who was at the head of the slow march, marveled at the progress they were making and at how easy it was.
According to his estimate, the vampires should be around ten thousand in number. This was after the initial population of 100,000 of the wayfarer had been whittled down by the vampires themselves.
The soldiers, on the other hand, were just 80 in number. Despite the fact that they were vastly outnumbered, victory is supposed to be theirs.
He wasn't surprised that the soldiers were winning. This is because even though the vampires had the advantage of numbers, they were very weak.
The vampires were new and weak. There were less than 10 f-rank vampires among the ten thousand of them. The rest were unranked.
Meanwhile, the weakest person in the Yggdrasil army had a strength of E-rank. That's the power required for someone to pass the advancement game for the professional league.
E-rank soldiers are the minority. Most soldiers were at the C-rank. So it is not surprising that the soldiers are winning. What was surprising was how it was to win.
Because of the use of sensory overload and special bullets, the vampires couldn't fight back at all. They might as well be wheat being harvested or grass being cut down.
Kelvin was certain that this would have been the case even if the vampires were stronger. He was sure that the vampires still wouldn't be able to resist even if they had the same level of strength as the soldiers.