A rebellion is a general revolt by disaffected inhabitants of a province, seeking independence from what they see as an oppressive and unjust overlord. Rebellions generally occur as a result of significant 
unhappiness in the pops of a province, which generate unrest and decrease 
provincial loyalty until tensions reach a boiling point and the province revolts. Individual rebellions of isolated provinces are rarely dangerous and can usually be easily suppressed, but widespread discontent can lead to a large wave of revolts that can seriously tax the military resources of a country or a complete collapse of its authority.
Unrest
Unrest represents the overall degree of discontent in a territory, and is generated by unhappy pops (those with a happiness below 50). The happiness of a pop depends on its culture and its religion, as compared to the country’s state religion and culture. Different pop-types also want different civilization levels to be happy: while 
tribesmen want it as low as possible, 
citizens and 
nobles will be rather unhappy if it is not high. Many other factors such as 
laws, 
stability, access to different trade goods, governor policies, and local buildings can also significantly affect pop happiness. The amount of unrest a pop produces differs based on its political weight, which is determined by its class; unhappy nobles are much more problematic than discontent 
slaves.
Every pop with less than 50% happiness will contribute to the unrest of the territory according to the following formula:
- [math]\displaystyle{ \text{Unrest}=10 \cdot \frac{1}{\text{Territory Population}} \cdot \text{Pop Political Weight} \cdot \frac{50% - \text{Pop Happiness}}{50%} }[/math]
Besides pop unhappiness, 
running out of food will also dramatically increase unrest in a territory.
Each point of unrest gives the following modifiers:
- -0.08 Territory Provincial Loyalty
−10% Pop Promotion Speed
+10% Pop Demotion Speed
−1 Migration Attraction
+25% Pop Migration Speed
Notably, unrest does not directly decrease a territory's output, though the output will usually be reduced anyways by the unhappy pops the generated the unrest in the first place.
If a territory has no unrest, it instead gets the following modifier:
- +0.10 Territory Provincial Loyalty
The Territory Provincial Loyalty modifier is additionally scaled according to the relative 
population size of the territory (compared to the population of the province as a whole) before being applied to the overall loyalty of the province. This means that, roughly, each pop in a province has roughly the same effect on territory loyalty before considering political weight; it is therefore often best to focus on the unrest and happiness coming from 
cities, as it is not only easier to appease the population by raising happiness (and over the longer term, assimilation and conversion) through city buildings, but cities also usually have more pops, and especially more upper class pops, which amplifies the effects of increasing their happiness. A relatively content city can often anchor an unhappy countryside and prevent the province from becoming disloyal.
In general, appeasing unhappy pops in a territory, whether by directly increasing their happiness or through the longer term processes of conversion, assimilation, and integration, is usually the best way to deal with unrest. Each 
fort point in a province also decreases the unrest in every owned territory in the province by -0.25, which can be another way to control unrest in a province if the country is willing to pay the maintenance costs.
Province loyalty
- 主條目：Province loyalty
Each province has a provincial loyalty value representing how willing it is to accept its owner's rule and obey orders from the capital. A province is considered disloyal if its loyalty goes below 33, at which point many interactions with the province will become unavailable, including building construction and manual pop movement.
Province loyalty is primarily decreased by unrest in its territories, weighted according to their population, as well as governor 
corruption. Besides addressing the main sources of discontent, province loyalty can be increased by appointing a more 
loyal governor, building certain buildings in cities, using the 
Harsh Treatment governor policy, and through certain ideas, 
inventions, and deities. 
Monarchs may also use the 
Anabasis action while in command of an army at a provincial capital to increase province loyalty.
A province's loyalty reaching 0 is the main trigger for a rebellion.
Rebellion mechanics
A rebellion will occur when the loyalty of a unoccupied province reaches 0. When that happens, the province will declare independence, either creating a new country with the name of the province or reviving a previously existing country in the area that was annexed. The rebelling nation will then either declare war with its former owner using the Independence wargoal for its province, which requires the revolt to retain control of its entire province in order to gain ticking warscore (the defending former owner must instead control at least one of the rebellion's territory to gain ticking warscore), or join an existing war of independence if another province of the same culture is already in revolt. For player-controlled nations, this can lead to a growing cascade of rebelling provinces if there is widespread discontent and falling provincial loyalty across the board, though AI-controlled countries get a boost of +30 province loyalty when a rebellion occurs that will generally prevent them from falling apart too quickly.
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