They began to march steadily towards the surface then moved towards the war zone. What the scout team managed to gain was really important info.
He knew that the war went very smoothly at the beginning. The armies under Mamor control managed to gain victory in 10 different battlefields.
The goal was reached so Mamor stopped the assault and began to withdraw to the village. This was the moment when a new mysterious monster army appeared and surrounded the whole withdrawing army.
That caused great causalities to Mamor's army, especially it was already in retreat with high morale. The weakest moment of any army was when it was at his highest moral point.
That false sensation with invincibility mixed with complete security added most deaths to the Mamor army. With his remaining soldiers and generals, he couldn't retreat and became trapped in this area waiting for rescue.