I just thought of this; unit instincts. A feature in which a unit can perform any task without the player's command. This can be in a time of need, when the enemy is charging into your unit's ranks. So before impact, their main instinct would be to form a wall and hold their line. Obviously, since this is done in a rush, this formation wouldn't work as well as it would if you set the command.
So, as you can tell, this feature works perfectly with the 'line of sight' feature. If a soldier in your unit sees an enemy unit charging, their main instinct is to get ready for battle. Instead of walking and ignoring the enemy (which will cause lot's of damage if the player isn't paying attention).
Whatcha think?