Sieges are to be avoided. Divines should be brought in to wipe forces away. Olephia, Anassa, Baalka and Irinika are all capable of causing enough devastation to breach castle walls and raze them to the ground. Without Divines, fortresses should not be sieged. Cities can be starved out through the raiding and obstruction of supply routes.
It is a radical change in warfare, but there is a simple reason. An army sieging faces inwards, to turn a city into a prison merely galvanizes the local population. They see directly who the enemy is, they can peer over the castle walls and immediately see who is responsible for turning their holds into a prison.
Most importantly. An army sieging can be counter-attacked from the rear.
There is little to be done in a situation like that, there is nowhere to retreat when the rear becomes a frontline, and the castle walls that once trapped the local population now trap you.
