A few minutes after the decision to send troops to attack the mobile fortresses through underground channels was made, there was a change on the battlefield.
An explosion occurred under a mobile fortress. This caused it to tilt and stop firing.
This had happened because one of the defenders had attached a bomb to the underside of the mobile fortress, where a barrier was protecting. Even though the fortress was a heavily fortified rank 5 artifact, its shell was still shredded by the bomb, and significant structural damage was inflicted on it.
The explosion of the bomb was like a signal to the troops hiding within the tunnels underground. They surged forward with a battle cry and rushed into the mobile fortress through the hole that had been blasted into it.
The invaders on the mobile fortress went forward to block and resist the defenders. So the mobile fortresses became small battlefields.
