How do catapults and other siege units work?
Siege units (catapults, cannons, and artillery) are have 2 unique abilities: one is to cause collateral damage, and the other is to reduce a city’s defenses. The latter works in the following way: when your catapult is next to an enemy city, you can have it bombard that city, reducing its defense bonus by 15% for catapults, 20% for cannons, and 25% for artillery. By doing this, you will help your units to conquer that city as the defenders will have less (or no) city defense bonus in their favor. Collateral damage is another option that siege units can undertake. By actually attacking the unit(s) on a tile like normal combat, your siege unit will cause collateral damage. This means that a number of units in a stack will suffer a drop in strength. This number can also be increased with the City Barrage I and II promotions. Siege units will also retreat from battle 25% of the time during a collateral damage attack. Because of this, siege units make large stacks of units prone to sufferin
