Siege artillery pieces, such as onagers, can be recruited in the same manner as other units. However, siege engines are constructed on-site and deployed when assaulting a settlement, taking a number of turns to complete before they can be used for an attack. Ranging from simple battering rams to hulking siege towers, they directly connect with enemy walls, but are heavy, slow moving and vulnerable to attack. As such, it’s advisable to escort them lest the enemy sally out to meet their besiegers. The following siege equipment is available, depending on the research of any pre-requisite technology:
The simplest form of equipment, this is simply a long ladder that can be leaned against a settlement's walls so troops can try to climb onto the battlements and capture the towers and gates. Control of a gatehouse enables other troops to enter the besieged settlement unmolested by missile fire or boiling oil.
Battering rams are a simple and effective way to break down settlement gates. Coming in three classes - light, medium, and heavy, each one carrying heavier armour than the class below it. Battering rams also affect the morale of the defenders - each blow acting as a deafening countdown until the assault begins, bringing almost-certain death with it.
Siege towers come in light, medium, and heavy classes, with a further two heights per class - 8 metres and 15 metres. Light towers give speedy access to settlement walls and some protection to the troops inside it. Medium towers are clad in improved hide armour, which better protects their troops. Heavy towers carry superior iron plate armour, meaning their troops are well protected from enemy missile fire.
When fighting a siege battle as the defender remember that the enemy will try to either sneak past your defences or rush them by force of arms. Use archers to kill approaching units and melee troops to kill those that get inside the walls! The enemy will try to wipe out all defenders, and if your men rout en masse from the settlement the battle is over.
The wall-mounted defences of a settlement depend purely on the upgrade level of its main building. The size of the walls is always the same, but arrow and scorpio towers are added as the main building is upgraded, eventually leading to bastions, which are artillery platforms you can use to position a single scorpion, ballista, or onager. Due to this, a single piece of artillery placed upon a bastion has more effective ammunition than it would normally carry as part of a battery. As such, the following defences are available to besieged occupants: