Attrition
Attrition is the loss of men due to desertion, disease, etc. A unit will suffer attrition if it ends turn in enemy territory during the winter months. Ships are not designed as ocean-going vessels, so ship crews and armies transported by sea will suffer attrition if kept away from the coastline for any length of time. A force that has been affected by attrition will have a flashing skull graphic on its banner and can be replenished when in friendly territory or merged with another depleted army or fleet.