The seeds of metamorphosis of caliphate into kingship were sown, as the second caliph Umar had feared, as early as the regime of the third caliph Uthman, who appointed many of his kinsmen from his clan Banu Umayya, including Marwan and Walid bin Uqba on important government positions, becoming the main cause of turmoil resulting in his murder and the ensuing infighting during Ali's time and rebellion by Muawiya, another of Uthman's kinsman. This ultimately resulted in the establishment of firm dynastic rule of Banu Umayya after Husain, the younger son of Ali from Fatima, was killed at the Battle of Karbala. The rise to power of Banu Umayya, the Meccan tribe of elites who had vehemently opposed Muhammad under the leadership of Abu Sufyan, Muawiya's father, right up to the conquest of Mecca by Muhammad, as his successors with the accession of Uthman to caliphate, replaced the egalitarian society formed as a result of Muhammad's revolution to a society stratified between haves and have-nots as a result of nepotism, and in the words of El-Hibri through "the use of religious charity revenues (zakat) to subsidise family interests, which Uthman justified as "al-sila" (pious filial support). " Ali, during his rather brief regime after Uthman maintained austere life style and tried hard to bring back the egalitarian system and supremacy of law over the ruler idealised in Muhammad's message, but faced continued opposition, and wars one after another by Aisha-Talhah-Zubair, by Muawiya and finally by the Kharjites. After he was murdered his followers immediately elected Hasan ibn Ali his elder son from Fatima to succeed him. Hasan, however, shortly afterwards signed a treaty with Muawiaya relinquishing power in favour of the latter, with a condition inter alia, that one of the two who will outlive the other will be the caliph, and that this caliph will not appoint a successor but will leave the matter of selection of the caliph to the public. Subsequently, Hasan was poisoned to death and Muawiya enjoyed unchallenged power. Not honouring his treaty with Hasan he however nominated his son Yazid to succeed him. Upon Muawiya's death, Yazid asked Husain the younger brother of Hasan, Ali's son and Muhammad's grandson, to give his allegiance to Yazid, which he plainly refused. His caravan was cordoned by Yazid's army at Karbala and he was killed with all his male companions – total 72 people, in a day long battle after which Yazid established himself as a sovereign, though strong public uprising erupted after his death against his dynasty to avenge the massacre of Karbala, but Banu Umayya were able to quickly suppress them all and ruled the Muslim world, till they were finally overthrown by Banu Abbas.