Alright, a lot of people have been asking this, so here goes.
Morale
You will see Morale ratings on both troops and provinces.
Troops gain and lose morale depending on how battles they are in and wars their country is in are going, and fight more effectively if they have higher morale.
Provinces gain morale every turn based on several factors, including the infrastructure in the province, and how long it takes to travel from that province to the capital of the nation controlling it. Additionally, when a nation's capital falls, the conqueror's civilians will begin celebrating, raising the morale of all provinces by roughly 10%.
Provinces additionally can lose morale. Spies on economic sabotage missions can sabotage the morale of the target country, dropping the morale of that province or even the entire country by roughly 10%. Battles going on in a province will slowly decrease its morale.
If a province is ceded to another country via a foreign policy treaty, the province's morale will drop radically; to roughly 40% if its morale is above that, 10-25% otherwise.
If a province is forcefully occupied, its morale will instantly drop to 25%.
If the empire controlling a province begins running out of raw materials (0, that is), then morale will drop dramatically and often, until your entire empire may dissolve into chaos.
Provinces with 30% morale or less will have enough dissatisfied population that riots will break out. Rioters can kill small amounts of troops if they decide to start an uprising (less than about 4,000), and if they manage to take over the country, they will proclaim their loyalty to another country (usually a nearby one that their original owner was at peace with) and cede themselves to that country, raising morale dramatically.
You can generally count on more than 5% morale increase per turn, which means riots rarely last longer than one turn if continuous fighting is not occurring in the area.
EDIT:
If anyone already playing is up for a second game, say so. We are getting more requests for a second game in general, so yeah.