When a civil war starts it causes unrest across all of that empire. If a general or governor doesn't have a lot of loyalty to you there is a higher chance he will start a civil war. Another new feature is how civil wars start, while it keeps some elements from Total War Rome 2 like the control over your faction, it adds new mechanics like loyalty. There are new events that occur at certain turns, some o these events will give your empire positive public order while others will lead to unrest and civil war.
