Fort with a temple.

Forts are structures which exist on the map and can be upgraded. The availability of forts depends on the nation's development level. In general, this corresponds to the ages, so that Early Ages are development level 1, Middle Ages are development level 2, and Late Ages are development level 3. However, certain nations are underdeveloped (for example, Early Age Mictlan has development level 0). Others are advanced (for example, Middle Age Ulm is development level 3). Forts serve as collection points for resources, supply depots for distribution to surrounding provinces, and shelter for troops in the event of a siege. Each fortress type has different attributes.


The admin value of a fort determines the percentage of resources from neighboring provinces that the fortress can collect. It also propagates supply into nearby provinces. The formula for this is (Administration x 4) / (Distance + 1). Thus, a fortress with admin 50 contributes 100 supply to adjacent provinces. Four provinces is the maximum distance for this supply propagation. Land forts cannot draw resources from sea provinces, and vice versa. Administration also increases the income of a province by (Admin / 2)%. Thus, a fort with an Admin value of 30 would increase the income by 15% of any province in which it is built.


The defense value of a fort represents the number of points of damage that must be done to a fort by an enemy siege before it can be attacked. Each turn a comparison is made between the strength of the sieging and besieged forces at a fortress. The difference between these forces determines the amount of damage done to the fortress' defense value.


The supply value of a fortress determines only how many units can be supplied inside thatfortress in the event of a siege. It does not affect the distribution of supply to surrounding provinces. Each turn a fortress is under siege, its supply value is divided by the length of the siege to determine the supply points available on that turn to the besieged units. Thus, on the fifth turn of a siege of a fortress with a supply value of 100, the fortress provides besieged units with 20 supply.

Values and upgradesEdit

The statistics for each fort and its possible upgrades are listed below. The fortresses themselves are in bold, and the upgrades are italicized. In order to build an upgrade, the prerequisite must already be present.

Name Development Prerequisite Cost Build time
Admin Defense Supply Other effects
Palisades 0-1 none 600 4 20 50 200 none
Wooden Towers 0-1 Palisades 200 1 2 50 N/A fires arrows
Fortress 1-2 none 800 5 25 250 400 none
Castle 2-3 none 1000 6 30 400 500 none
Citadel 3 none 1200 7 35 550 600 none
Gate House 1-3 Fortress/Castle/Citadel 200 1 2 100 N/A fires arrows
Towers 1-3 Gate House 200 1 2 100 N/A fires arrows
Additional Towers 3 Towers 200 1 2 100 N/A fires arrows
Killing Ground 1-3 Gate House 200 1 2 100 N/A fires arrows
Deep Well 3 none 100 2 2 N/A 400 none
Supply Storage 0-3 none 100 1 2 N/A 400 none
Underground Storage 0-3 none 200 2 2 N/A 400 none
Road 1-3 plains/forest 200 5 5 N/A N/A negates difficult terrain in province


Fortresses must be reduced before they can be stormed. To reduce a fortress, its Defense value must be reduced to zero. Each turn, the total reduction strength of the besiegers is compared to the total repair strength of the defenders.

Reduction strength = unit strength squared/100

  • Flying units get +1

Repair strength = unit strength squared/100

  • Flying units get +1
  • Mindless units are only worth 10% of calculated value

The difference is subtracted from the fortress defense value if the Reduction strength is greater. If the fortress has been damaged, and the repair strength is greater, the difference is added back to the defense value, to the maximum of the original value.

That's why you get the message sometimes when you're the besieger, that "the enemy is repairing the walls faster than we can destroy them. We need more men." This means the repair value is higher than the reduction value, and the besieged units are actually fixing the walls. There is no way for the besieger to know how close a fortress is to being breached. The defender, however, can click on the fortification location button in that province, and the current defense value will be displayed. Fortresses which are damaged but not besieged are automatically fully repaired.

When a fortress is besieged, it provides its supply value to the defenders, divided by the number of turns of the siege. So on the first turn of a siege, a fortress with 300 supply provides 300 supply points on the first turn of the siege, then 150, then 100, then 75, then 60. Units which are unsupplied suffer the starvation effect, and units which starve for two consecutive turns can become diseased. These diseases will then spread inside the fortress!