Mu'awiya I, the first Umayyad caliph, died in 680 and was succeeded by his son, Yazid I. Yazid I was a cruel and unpopular ruler, and his reign was marked by civil war and unrest. He was eventually killed in battle in 683, and the Umayyad caliphate began to decline.
Mastering Mu'awiya I: Unlocking the Legacy of the First Umayyad Caliph