This career of conquest was interrupted by the great civil wars. The Arabs knew of nothing between entire liberty and absolute monarchy. The latter was the form which the caliphate first took, but it was universally assumed that the ruler was bound to abide strictly by the laws of religion. When Othman, grown old and feeble, was led by excessive nepotism and other causes into a breach of the latter, the result was a rebellion, in which he ultimately perished (656). The murder was followed by years of civil broils, and some decades later the whole thing was enacted afresh. The war was waged under religious pretexts, and to some extent from religious motives; but it was in the main a struggle for sovereignty between various members of the Koreish. Tribal animosities old and new were brought into play, and induced the tribes to throw in their lot with one or other of the leading parties. The outcome of the two great civil wars was that in each case the ablest man placed himself at the head of the empire; the first to do so, after the murder of Ali, Mohammed’s son-in-law, being the Omayyad Moawiya, son of Abu Sufyan, the leader of the heathen of Mecca against Mohammed. In his reign Damascus, where he had lived as governor for many years before, became the capital in place of Medina. The victor in the second instance was Abd al-Melik, of another branch of the Omayyad family. They were both men of great capacity but essentially worldly-minded. One of the prophet’s grandsons, a son of Ali, had made his peace, while another, Husain by name, fell in a foolish attempt at rebellion (680); though he was thenceforth regarded as a martyr, and much blood was shed to avenge his death on the rulers _de facto_. The pious stood aloof, sorrowful or indignant, but the sovereignty remained in the hands of the Omayyads. To Europe these civil wars were nothing short of salvation. Had they not checked the career of Arab conquest, Islam might even then have subjugated Asia Minor, the Balkan peninsula, and the whole of Spain, and spread beyond it to Gaul and remoter lands.