A wall in Age of Medieval is not one object with one health bar. Every stretch you dragged has its own.
When a trebuchet finds its range, that stretch goes from whole to damaged to breached, and the battle changes: there is now a second way in, and it is not where you put your towers.
The breach does not heal when the fighting stops. A gate that was broken stays broken, a ring that was opened stays open, and a village with an open ring is easier to take the next time. Repairs are building work, done by your people with your timber.
The other lords repair their walls too. If you fail to take a town, do not expect to find the same hole waiting next season.
Age of Medieval is developed by UnderStudio in UnderStudio 2D and published by Brasa Interactive. It releases on 17 May 2027.
Official site: https://ageofmedieval.com/