This is where you command your army and try to claim victory over a hostile faction's army or settlement. There are two types of War Fields: Planetary Surface War Fields, and Space War Fields.
Each War Field supports up to 1000 combat units, so it's truly a massive battlefield that's a wonder to behold. To prevail, not only do you need to strategize and command your armies to take down key enemy targets, but you also need to stay on your toes and engage your enemies directly with your own weapons.
You can bring various combat units, vehicles, and field-deployable structures into each War Field. A few examples of structure you can bring are turrets, field helipads and watch towers (so you can climb atop and snipe from afar).