Quote Originally Posted by Weebeast
Does a unit have to be hidden as it's charging to get the bonus or it doesn't matter as long as a unit's hidden once?
If you order a hidden unit to charge an enemy unit, that unit will suffer a morale penalty, even if your unit has to jog over half to map to reach their target. Take care though that your units will be revealed if the enemy comes close, and at higher difficulty levels the A.I. notices the missing units and will search for them.