Battlegrounds are locations on the Map that have either been occupied by Balur's Orcish horde, or are under threat of imminent attack. By waging war upon these Battlefields you can claim valuable trophies and Quest items, liberate friendly Units, seize Resources, or gain Experience Points.
There are two types of Battlegrounds – Offensive and Defensive. Send Offensive Units to destroy Orcish forces foolish enough to take up positions near your Castle (Offensive Battlegrounds – highlighted red in your Eagle's nest and on the Map).
Send Defensive Units to evacuate unarmed villagers and subjects from the attacking Orcish Horde, and leave nothing but ashes behind you (Defensive Battlegrounds – highlighted green in your Eagle's Nest and on the Map).