The Path of Kings
Morale is an important aspect of mass combat. Certain situations force a morale check on military units, using the military unit’s will save.
When a unit is disbanded or defeated, adjacent allied units have to make a will save vs. DC 10 + 1/2 the HD of the defeated unit. If a unit fails the check, on its next turn it has to disengage combat, and move away from any enemy units. If it cannot take a move action, it has to skip its turn.
When a unit suffers damage which brings it below 50% of its hit points, it has to make a will save vs. 10 + 1/2 its HD or fall into chaos. Each round it has to skip its turn until it succeeds on the will save.
When a unit disengages from combat while the enemy has not been defeated, adjacent allied units have to make a will save vs. DC 10 + 1/2 the HD of the disengaging unit. If they fail the check they have to disengage and move away themselves. If they cannot withdraw, they have to skip their turn.
Each time a unit takes damage by a unit which is at least three tiers “bigger” than itself (e.g. a squad versus a brigade), it has to make a will save vs. DC 10 + 1/2 the HD of the enemy unit. If the unit fails the save, during its next turn, it has to disengage combat and move away from the enemy unit.