During the last year of 'Ali's caliphate, Muawiya b. Abi Sufyan, the governor of Syria and the main challenger of 'Ali, managed to bring a large part of the Muslim empire under his control. He also had the authority vested in him, though under doubtful and ambiguous circumstances, by 'Amr b. al-As at the arbitration of Adruh after the battle of Siffin. Nevertheless, he could not claim for himself the title of Amir al-Mu'minin while 'Ali was yet alive. 'Ali was still the legitimate caliph chosen by the community at large in Medina; this was not publicly repudiated by the community as a whole, nor was the declaration of Abu Musa al-Ash'ari deposing 'Ali and that of 'Amr b. al-'As installing Mu'awiya accepted by the Muhajirun and the Ansar. Thus, despite all his military and political successes, Mu'awiya could do no more than style himself only as Amir.[327]
With 'Ali's assassination, the road was finally cleared for the realization of the ultimate goal of Mu'awiya's ambitions. The very favourable circumstances that prevailed in the form of the impotence of Medina and the remnant of the pious section of the community and the vacillating nature of the Iraqi supporters of 'Ali's successor Hasan, coupled with the characteristic shrewdness of Mu'awiya, made it easier for him to complete the task he had initiated after the death of 'Uthman: the seizure of the caliphate for himself and his clan.
Hasan, the elder son of 'All and Fatima, was acclaimed as caliph by forty thousand people in Kufa immediately after the death of his father.[328] We are told that at the battle of Siffin (Safar 37/July 657), less than three years before his death, 'Ali had in his army seventy Companions who fought for the Prophet at Badr, seven hundred of those who renewed their allegiance to Muhammad (bay'at ar-ridwan) at the time of the treaty of Hudaybiya, and another four hundred from other Muhajirun and Ansar.[329] Many of them were still residing in Kufa with 'Ali as he prepared for a final encounter with Muawiya. They must have participated in the election of Hasan and must have accepted him as the new caliph, otherwise our sources would have recorded their opposition to his succession. To this there is no testimony at all. The people of Medina and Mecca seem to have r
