Patrols, castle defenses and inns haunting

[Herode]

Hi gentlemen,

my answer is about province defense : I understand that 'patrolling' units will defend the province against attacking ennemies, and 'defending' troops will stay in the castle in order to prevent ennemies from storming it. But what about the other units ? What about the ones who are building temples, forging items or searching for some kind of arcane candy ? Are they automatically destroyed by attackers ? Will they retreat ? Or what ?