+1 combat result if your unit is fighting the enemy unit's flank.
Fighting a foe in its flank is a great advantage. The enemy warriors cannot easily turn to combat their attackers, and the sudden appearance of an enemy from an unexpected quarter has a psychological value all of its own. Therefore, if one or more of your units are fighting the enemy in its flank, you receive +1 combat result. If the enemy unit is engaged in both flanks, you receive +2 to the combat result instead.