All Cavalry models with this special rule cause Fear in any turn in which they charge.
In addition, in any turn in which a Cavalry unit where the majority of models have this special rule makes a successful charge and wins the subsequent combat but does not break the enemy, they may attempt to disengage from the fight by passing a Leadership test.
If successful, the unit will make a flee move away from the enemy in a direction of your choice, as long as they do not flee through any units, in which case they must stop within 1".
The enemy may not pursue a unit disengaging from combat in this manner. After making its flee move, the unit will automatically rally and reform. If this move would take the unit off the battlefield, treat this as the unit having pursued off the table.