Answer
Hasan ibn Ali ruled as caliph for only seven months. His reign was marked by political instability and internal strife. He faced opposition from various factions, including those loyal to his rival, Mu'awiya ibn Abi Sufyan. To avoid further bloodshed, Hasan eventually abdicated in favor of Mu'awiya, ending the First Fitna (civil war) and establishing the Umayyad dynasty.