In order to gain control of a garrisoned and fortified settlement it is often necessary to lay siege. During a siege your troops surround it and can either attempt to starve the defenders into capitulation or launch a direct assault using siege equipment (both artillery and engines such as rams and towers). The besieged force may choose to sally out to meet you on the battlefield, but be aware that defeating them will not automatically result in the surrender of their settlement to you. Victory in a siege turns ownership of the province over to your faction. You then have a number of options available to you, detailed below, that have a scale of penalties attached to them. In addition, there will also be public order issues if the new owners of a region are of a different culture to that of the indigenous populace.
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.
Whilst your armies protect threatened regions, your settlements have their own local garrisons to act as rudimentary defence forces. These men are stationed within a settlement and cannot leave their posts to join your armies on campaign. The types of garrison troops available depend on the buildings constructed in a particular settlement. Whilst not the most skilled soldiers, garrisons who defend against besieging forces will develop strength and experience over time. Ports have an equivalent garrison navy to protect against raids and naval blockades.
If you choose to encircle (minor settlement) or maintain siege (major settlement) when attacking, your force will not engage in battle, but weather the enemy down instead until the defenders either attempt to break the siege or surrender from starvation. You can see the number of turns until they surrender in the bottom left-hand corner of the siege battle panel. Once you have chosen to encircle/maintain the siege you can break it again at any time.
If a besieged settlement has a port attached to it the populace within continue to receive limited supplies from outside. This doubles the time taken for the settlement to surrender. If you blockade the port as well as besiege the settlement they will surrender from starvation much quicker.
Following the conquest of a region there will continue to be a degree of unrest in response to the change of ruler, especially one belonging to a different culture. This is called "resistance to occupation". It declines gradually over time, but never totally disappears, so it is wisdom to leave adequate garrisons behind and manage taxation carefully.
This option is not available if you are playing as a barbarian faction. Your force rampages through the settlement, damaging buildings, and robbing the populace. Looting carries a public order penalty and diplomatic relations between your faction and the previous owners of the settlement are damaged. Anyone captured is automatically enslaved.
This option is only available if you are playing as a barbarian faction. Your force rampages through the settlement, destroying buildings, robbing, and killing the populace. You do not capture the settlement, instead leaving it a ruin of little use to its owners, who also suffer public order problems as a result of the sacking. Naturally, diplomatic relations between you are damaged. Anyone captured is automatically killed.
Your force can only liberate a settlement if the liberated faction was the original owner of both the settlement and region at the start of the campaign, and has since been destroyed. Control of the settlement is returned to them, all captives are released, and diplomatic relations between you become extremely friendly.