Zayd led a rebellion against the Umayyads in the mid 8th century, renewing the hostilities that existed between the Umayyads and the Hashemites. Zayd was killed during fighting in 740.
After his death, some felt that he was the rightful sucessor to his father, rather than his half-brother Muhammad al-Baqir. Those who believe in this line of sucession form the Zaidi sect within Shiism.