Siege units are units that can breach gates and walls.
The known Siege units are:
Units with digging special can dig into city walls. However, they need Siege Towers to act as effective siege units. Siege Towers (which are items, not units) act as portable shelters for diggers and reduce their otherwise excessive losses from city defences.
Battery Chargers may be horse units akin to Weiner-Rammers.
- Trebuchets First Intermission 3