Extracted from the combat
First, the attacker's strength is modified:
- If the attacker is a veteran, its strength is multiplied by the bonus associated with its veteran level.
Next, the defender's strength is modified:
- If the defender is a veteran, then its strength is multiplied by the bonus associated with its veteran level.
- Then the defender's strength is multiplied by the defense factor of the terrain it occupies.
- Next, the defender's strength is doubled if it is a Pikeman unit defending against a mounted unit.
- If the defender is an AEGIS Cruiser defending against airborne units (including missiles and Helicopters), the defense is quintupled.
- The defender's strength is doubled again if it is in a city with a SAM Battery and the attacker is an air unit (other than a Helicopter or a missile).
- An SDI Defense doubles the defender's strength against missile attacks.
- If the attacker is a ship and the defender is in a city with a Coastal Defense, the defender's strength is doubled.
- Against land units (other than Howitzers) and Helicopters, defending units in a city with City Walls have their strength tripled.
- If the defender is in a fortress (and not a city), its strength is doubled.
- If the defender is a land unit, and is either fortified or inside a city, its strength is multiplied by 1.5.
- Finally, if the attacker is a fighter and the defender is a helicopter, the defender's strength is halved.
If, after these modifications, the attacker has a strength of 0, it automatically loses. Otherwise, if the defender has a strength of 0, the defender loses.
The firepower of the attacker and defender are also modified.
- If the defender is a ship and is inside a city the firepower of the attacker is doubled and the firepower of the ship is set to 1.
- If a fighter is attacking a helicopter the firepower of the helicopter is set to 1.
- If a ship is attacking a land unit on land the firepower of both is set to 1.
After these preliminaries, combat occurs, as long as both units are still alive (i.e., hit points are greater than 0). Each round, a random number between 1 and the sum of the attacker's and defender's strengths is generated. If this number is greater than the defender's strength, the defender loses hit points equal to the attacker's firepower. Otherwise, the attacker loses hit points equal to the defender's firepower. The first unit to reach 0 hit points (or negative hit points) loses.