The soldiers kept firing for hours, their whole bodies turned numb from all the recoil the BC-79 gave them.
But the army had prepared a shift system for this. When the sun was about to set, a new group of refreshed soldiers came out of their slumber and replaced the tired soldiers.
With new soldiers replacing them, the shooting became even more efficient and effective. More undead died with fewer bullets.
Despite that, the undead army, looking like a black flood, still advanced forward little by little to the wall. The boulders that hindered their way were destroyed one by one by the explosion. That let the undead move more freely.
The army couldn't do much about that. The explosive ball blanketed the entire area, exploding everyone and everything around it, so they couldn't help but also destroyed the boulders too.
