Again, that which had happened after the election of Aly, might happen again at any fresh accession to the throne. Zobeir and Talha raised the standard of revolt on the plea that their oath was taken under compulsion; while between Aly and Muâvia, there followed a long and doubtful contest. The internecine struggle had imperilled the existence of Islam. Not only had the ranks of the Faithful been seriously thinned by the blood shed on either side; but, from without, enemies might at any moment have taken advantage of the strife. Muâvia, in point of fact, made a truce with the Byzantine Court while the civil war impended. But if a similar opportunity again offered, the foes of Islam might not be so forbearing, and a fatal wound might be inflicted thus upon the empire torn by intestine conflict. Influenced by such considerations, as well, no doubt, as by the desire of maintaining the Caliphate in his own line, Muâvia entertained the project of declaring his son, Yezîd, to be the Heir Apparent. [Sidenote: Muâvia’s design to nominate his son Heir Apparent.]By securing thus an oath of fealty to his son throughout the Moslem world, he would anticipate the event of his own decease, and thus prevent the peril of a contested election when it did occur. Ziâd, summoned to advise, was favourable to the design, but enjoined deliberation, and a preliminary cautious canvass throughout the provinces. He also counselled Yezîd, who was devoted to the chase and careless of public affairs, to amend his ways in preparation for the throne, and show before the people a character more fitted for the high dignity in store for him. Moghîra likewise was strongly in favour of the scheme.[582] But it was not till both these counsellors had passed away, that Muâvia found himself in a position to proceed with the design. [Sidenote: Yezîd declared Heir Apparent. A.H. LVI. A.D. 676.]