Know Your Place

A Peasant Rabble uprising does NOT count - it has to be a proper faction civil war. Easy setup: the 867 Umayyads start on the brink of one, especially if you surrender the opening wars and let vassal opinion crater. Refuse the faction's ultimatum, crush the rebels to 100% war score, done. Or engineer one in any big realm - raise crown authority, imprison a few people, and someone will oblige. The dread you farm for Dreadful Ruler is a reliable way to provoke it.