Persistence!

Not only would humans be pushed further and further back, but as long as the evolved intelligent zombie life forms were to control the S3s, S4s, and Hunters to launch an all-out assault, they could easily overrun the human troops.

At the same time, with the loss of industrial cities and production lines, the expenditure of resources and ammunitions could not be compensated, making the task for the human soldiers even tougher.

Once the zombie army was to overrun all the cities that Yue Zhong had painstakingly recovered, then the humans would have to fall back like rats and hide where they could. Even if they could evade death, there would be no more future, nor hope.