interference from Medina, especially since the new caliph Uthman, who succeeded Umar in 644, was a relative of Muawiyah, both being members of the aristocratic Umayyad branch of the Quraysh. Muhammad belonged to another clan of the same tribe. The army was kept in fit condition by semi-annual raids into the 'land of the Romans 5 — Asia Minor.
For the defence of a province bordering on the sea, Muawiyah realized that a body of disciplined, loyal troops did not suffice. In Acre he found fully equipped Byzantine shipyards which he developed into an arsenal second only to that of Alexandria. The new Moslem fleet, doubtless manned by Greco-Syrians with a long seafaring tradition, took Cyprus in 649 despite the reluctance of desert-reared caliphs to approve of expeditions across the alien sea. Rhodes was pillaged in 654 and in the following year the long-supreme Byzantine navy was virtually annihilated by the simple expedient of tying each Arab ship to an enemy vessel and converting the engagement into a hand-to-hand conflict.
Muawiyah, however, could not take full advantage of these exploits by his admirals and generals. Domestic dis- turbances leading to civil war were convulsing the Moslem world. In 656 Uthman was murdered by rebellious partisans of Ali, first cousin of Muhammad and husband of his only surviving daughter Fatimah. These partisans (Shiah) in- sisted that Ali was the divinely designated and therefore the only legitimate successor, and that his descendants were entitled to the caliphate by hereditary right. After some deliberation he was proclaimed caliph.
The caliphate of Ali was beset with trouble from begin- ning to end. The first problem was how to dispose of two rival claimants, Talhah and al-Zubayr, who with their fol- lowers in Hejaz and Iraq refused to recognize his succession. Both men were defeated and killed in a battle near Basra in December 656. Ali established himself in his new capital