Wars open between two regions and last 24 hours; active fronts are listed under Battles. To hit, your profile must be physically present in the war’s source or target region with the journey completed.
Land wars use tanks, drones and missiles; naval wars use ships only; in missile wars both sides use missiles only. Damage is set by Military Power, Headquarters, Research, level, the military base, the War Academy and homeland; Premium gives no damage bonus. The final damage is calculated on the server. Your party at the moment of the hit is written to the contribution record; switching parties later does not move past damage.
When time ends, the side with the decisive damage advantage wins; on a tie the defending side is kept. The result and region ownership are recorded atomically and battle history is not rewritten.

War Formula
Reading the battle screen
Location and travel
Training and action rights