Marshall Loren had no plans to stay in Fog City for too long. After receiving the King's appointment and permission for war, he had to hurry to Dover.
That is where the Old Imperial Guard is stationed.
The reason it is called the "Old Imperial Guard" is to distinguish it from the Guard of Fog City that was formed after the establishment of the Golden Flower Kingdom. The old guard are veterans who have served the King since the West Lan Kingdom period. They are the most powerful, honorable, and loyal force in the kingdom.
They only obey the will of the king himself, equivalent to King Louis's "private army".
Marshall Loren started his military career there.
He is the pride of the Old Imperial Guard.