Defending a castled province without patrolling?

[Boron]

How to do this?

If I don't want to patrol due to pop loss, or by another reason, how can I defend the province, assumed there's a castle in the province itself?

hm i have a idea :
build a garrison for each caste and move them to the other castle . iirc there is a order move + patrol . this way when they are moved each turn they shouldn't patrol but defend the castle .