From Conflict of Nations Wiki
Insurgencies are the result of rebellions within a nation. These act as a global threat and are listed as their own nation under the campaign’s ranking. Insurgencies can only cause an uprising in cities that have a low morale, they do not expand outside of cities they conquer . When conquering a city, morale will be low, be sure to monitor your Target Morale and leave a garrison while the city recovers. Otherwise, the city may rebel and spawn insurgencies which can cause you problems later on.
How Insurgencies Spawn
Cities are at risk of rebellion while their morale is ~33% or below, but this risk increases greatly when the morale of a city is under ~25%.
- Undefended cities are immediately captured the moment insurgencies spawn on them, but insurgencies will not conquer the city until your troops are defeated.
- If you have units stationed in a city/province which is hit by an insurgency rebellion, they will engage in combat. In that case, your units will benefit from a defensive garrison bonus.
Revolts will occur once at any time during the 24 hour day, the timer is absolutely random 24 hours at what specific time they will revolt. It is important to note that each city type has it's own respective timer which will apply to all city types.
- ALL Homeland cities under your control on Day 1 will (if applicable) revolt @14.00 ingame time. But on Day 2 another random timer is set for 18.00
- ALL Occupied cities under your control on Day 1 will (if applicable) revolt @19.00 ingame time. But on Day 2 another random timer is set for 12.00
- ALL Annexed cities under your control on Day 1 will (if applicable) revolt @22.00 ingame time. But on Day 2 another random timer is set for 2.00
When the morale is low enough, more insurgencies will spawn. They will not conquer other cities and neighbouring provinces, but will increase in numbers. As soon as the city is conquered, the insurgencies will remain stationary there protecting it instead.