Ghost Riders to an enemy castle province

[Viajero]

Is there any point in this? Does it prevent an enemy from retreating there in the same turn for example or is is just useless?

[Ragnarok-X]

Well, it depends. YOu can take out the PD and if an enemy commander is set on "patrol" he will fight together with his PD against your ghost riders.

[Psycho]

Ghost riders will destroy the pd before his retreating army gets there making the province independent, so if you move your army there in the same turn you will get a fight with his retreating army, instead of them safely moving inside the castle.