A Rebellion is an event in Empire: Total War.
Rebellions take place in regions where public order for either or both classes is negative for three turns. In the first turn, workers go on strike and the nobility write a letter of demands to the government. This has no material detriment; it simply serves to inform players of a region's growing unrest. In the second turn, if the lower classes are still unhappy, then they riot, causing damage to a random building in the region. If the populace is still not assuaged, a rebel army spawns at the beginning of the third turn. This army consists of troops that are available only to that region; a minor region with a magistrate, for example, may only spawn Militia in its rebel army, while a major region with fully upgraded centers could produce anything from Guards to 24-lber Foot Artillery.
The rebels' goal is to take the capital of the region. They cannot take other regions; in fact, they cannot leave the region that they are spawned in. Over time, rebel armies can grow if they are not put down. Should they attack the region capital, it will not spawn Firelock Armed Citizenry to aid in the defense. If they are defeated, then region gets a +6 repression bonus due to the crackdown, which diminishes by 1 every turn. This repression bonus also applies to any rebellious regions that have been newly captured or recaptured.
Most regions (such as Iceland and Anatolia) spawn a rebel army that simply take a region into a state of rebellion, causing it to be "at war" with every other faction until it is taken. However, should a rebellion spawn in the home region of a faction, then a successful rebellion leads to that region joining the faction. If a rebellion occurs in the home region of a faction was previously destroyed or otherwise not present (such as Ireland, France, or Bijapur), a successful rebellion leads to the emergence of a new faction. Should a faction retake its home region while a rebellion is taking place, the rebel army automatically joins its parent faction.
Oftentimes, rebellions are unavoidable. Public unrest is typically very large in a newly captured region, and multiple rebellions may rise and have to be put down before the region is fully placated. An easy way to deal with rebellions is to destroy any schools present, as schools often cause large amounts of unrest. Another way of making rebellions easier to handle is to destroy any recruitment centers in the region, forcing the rebelling armies to only spawn Militia.
A rebellion that occurs in a faction's home region is a Revolution, which has its own separate mechanics.