Also known as a "Fortitude Status", these are ratings given to each realm to determine the amount of damage it has endured over a given period. For each hostile action that is successfully performed on an opposing realm, the Fortitude Rating of the opposing realm will increase slightly. This allows neighbouring allies an easy way to determine how much damage an individual realm has sustained and how effective it can contribute to any future war efforts. However as time goes by and the realm begins to recover, the Fortitude Rating will gradually decrease until a status of "None" is reached

There is a direct correlation between "Fortitude Status" and "Valor Rankings". Valor penalties will apply if a realm continues hostile actions against an opposing realm which has already sustained heavy damage with a level of "Moderate" or "High" Fortitude Ratings. In this way, realms that have been the victim of multiple hostile actions have a chance to recover

Members : Fortitude Ratings for registered members are slowed, therefore giving almost twice the normal recovery times

Realm Fortitude Ratings Explaination
None
Minimal Hostile Actions On Your Realm
Low
Tolerable Hostile Actions On Your Realm
Moderate
Considerable Hostile Actions On Your Realm
High
Severe Hostile Actions On Your Realm

The act of "kicking a player whilst he is down" is frown upon within the Feudal World and is penalised accordingly.
For more information see Valor Ranks.