669 against Constantinople, where Yazid's success served to dispel any doubts that the puritans might have entertained regarding his qualifications. And now Muawiyah, after being sure of the capital, summoned deputations from the provinces and took from them the oath of allegiance to his favourite son. Unsympathetic Iraqis were cajoled, coerced or bribed.
This master-stroke was a landmark in Islamic history. It introduced the hereditary principle, which was followed thereafter by the leading Moslem dynasties. It established a precedent enabling the reigning caliph to proclaim as his successor him among his sons or kinsmen whom he con- sidered competent and to exact for him an anticipatory oath of allegiance. The designation of a crown prince tended to promote stability and continuity and to discourage ambitious aspirants to the throne.
Despite his unparalleled contributions to the cause of Arabism and Islam, Muawiyah was no favourite with the Arab Moslem historians. Nor were his 'tyrannical' lieuten- ants. The explanation is not difficult to find. Most of those writers were Shiites or Iraqis or Medinese and thus anti- Umayyad. As historians they reflected the puritanical attitude which resented the fact that he was the man who secularized Islam and transformed the theocratic caliphate into a temporal sovereignty. He is blamed for several innovations abhorrent to pious conservatives. The fact remains that such was the example of energy, tolerance and astuteness he set before his successors that while many of them tried to emulate it few came near succeeding.
As long as the rule of powerful Muawiyah lasted, no Alids dared dispute his authority in an overt act; but the accession of the frivolous Yazid was an invitation to seces- sion or rebellion. In response to urgent and reiterated appeals from Iraqis, al-Husayn, younger son of Ali and Fatimah, now declared himself the legitimate caliph. At the head of a weak escort of devoted followers and relatives,
