A siege allows enemy troops to lower the morale of a domain in order to trigger an insurrection, if the average happiness of the inhabitants drops to 0%. Units outside the domain are not counted in this calculation. An insurrection is a prerequisite for the [URL=/help/act?type=conquer]conquest[/URL] of an organisation. While multiple concurrent sieges can stack, their combined effect on happiness is capped at -50. In some cases, this won’t be enough to cause an insurrection, and the conqueror will need to find other ways to affect the population’s morale — such as attacking them, looting them, or preventing prayers and entertainment.