I am wondering why the defeated army cannot inflict casualties (except being very lucky with the 2 ToB skull incons) and just defend itselft with towers though.
The answer from 1st edition rulebook wrote:
Designer Note: Though casualties were obviously inflicted on both sides of a medieval battle, actual losses were far less than those of modern battles. Typically,
far greater casualties were inflicted after a medieval battle ended. A clever winning leader would press his victory by outflanking, pursuing, and slaughtering the broken enemy army as it retreated. In the A GAME OF THRONES board game, each unit represents a large force of warriors, and even one or two casualties should represent a stunning loss for the losing side.