Who participates in a battle?

[JJ_Colorado]

Hi,

I am in a game where I have the following in a province:
castle
leader in "academy of war" site
leader pillaging
leader "calling shadows"
leader "hiding"
leader moving into the province from outside
leader sneaking into the province from outside
leader searching for magic sites
leader patrolling
leader on defend orders

If an enemy army moves into my province, who fights them and who hides in the castle? Some of these seem easy but others I really have no idea.

Thanks
John