In Age of Empires III, siege units are units that resist building fire and generally have high siege damage. They possess both the Siege Unit and Siege Trooper tags in-game and are referred to as AbstractSiegeTrooper in the game files.
Siege units are specifically differentiated from artillery units when damage multipliers come into effect. Counter-artillery units such as Culverins and Hand Mortars only deal their attack bonus against artillery units like the Falconet or Mortar but will not deal bonus damage against siege units.
Buildings usually have a x0.5 multiplier penalty against siege units for both their ranged attack and anti-ship attack. Notable exceptions are the Fort, Agra Fort and Dock which do not have an anti-ship attack damage reduction, and the Town Center which does not have a ranged attack penalty against land siege units.
The following is a complete list of siege units:
- Hand Infantry
- The Maya Holcan Spearman and the Puma Spearman were tagged as Siege units before the Definitive Edition.