Basically this is an idea for a new structure: The Siege camp.
Placing a siege camp on the edge of an enemy territory would place that territory under the “siege” status effect which prevents them from building new structures and doubling the cost of all repairs until the siege has ended… (The increased repair cost debuff does not stack)
The siege camp degrades over time and requires regular repairs to maintain…
Siege camp also functions as an improved carpenters bench at which siege fortifications and weaponry can be built… (Things like the trebuchet, palisades, a new log based fence/wall, arrows, and the like.)
Anyways I thought it would be neat to have a way to lay siege to a base and actually turn it into a battle of attrition where walls stay destroyed when destroyed until you can drive back the attackers and break the siege…)