The losing unit in a combat must pass a Leadership test or flee. This Break test is modified by the amount by which the unit lost the combat.
In the brutal hack and slash of close combat, it is rare for warriors to fight to the last man. Defeating the enemy is much easier if you can break the resolve of your opponent.
The side that loses a round of close combat must take a test to determine whether it continues to stand and fight, or breaks from the combat and runs away. This is called a Break test. Troops that are better led, braver, and more professional are more likely to stand firm, while wild, temperamental troops are far more likely to run for it.