To return to our narrative. No sooner was ‘Alí proclaimed Caliph by the victorious rebels than Mu‘áwiya b. Abí Sufyán, the governor of Syria, raised the cry of vengeance for ‘Uthmán and refused to take the oath of allegiance. As head of the Umayyad family, Mu‘áwiya might justly demand that the murderers of his kinsman should be punished, but the contest between him and ‘Alí was virtually for the Caliphate. A great battle was fought at Ṣiffín, a village on the Euphrates. ‘Alí had well-nigh gained the day when Mu‘áwiya bethought him of a stratagem. He ordered his troops to fix Korans on the points of their lances and to shout, "Here is the Book of God: let it decide between us!" The miserable trick succeeded. In ‘Alí's army there were many pious fanatics to whom the proposed arbitration by the Koran appealed with irresistible force. They now sprang forward clamorously, threatening to betray their leader unless he would submit his cause to the Book. Vainly did ‘Alí remonstrate with the mutineers, and warn them of the trap into which they were driving him, and this too at the moment when victory was within their grasp. He had no choice but to yield and name as his umpire a man of doubtful loyalty, Abú Músá al-Ash‘arí, one of the oldest surviving Companions of the Prophet. Mu‘áwiya on his part named ‘Amr b. al-‘Áṣ, whose cunning had prompted the decisive manœuvre. When the umpires came forth to give judgment, Abú Músá rose and in accordance with what had been arranged at the preliminary conference pronounced that both ‘Alí and Mu‘áwiya should be deposed and that the people should elect a proper Caliph in their stead. "Lo," said he, laying down his sword, "even thus do I depose ‘Alí b. Abí Ṭálib." Then ‘Amr advanced and spoke as follows: "O people! ye have heard the judgment of my colleague. He has called you to witness that he deposes ‘Alí. Now I call you to witness that I confirm Mu‘áwiya, even as I make fast this sword of mine," and suiting the action to the word, he returned it to its sheath. It is characteristic of Arabian notions of morality that this impudent fraud was hailed by Mu‘áwiya's adherents as a diplomatic triumph which gave him a colourable pretext for assuming the title of Caliph. Both sides prepared to renew the struggle, but in the meanwhile ‘Alí found his hands full nearer home. A numerous party among his troops, including the same zealots who had forced arbitration upon him, now cast him off because he had accepted it, fell out from the ranks, and raised the standard of revolt. These 'Outgoers,' or Khárijites, as they were called, maintained their theocratic principles with desperate courage, and though often defeated took the field again and again. ‘Alí's plans for recovering Syria were finally abandoned in 660, when he concluded peace with Mu‘áwiya, and shortly afterwards he was struck down in the Mosque at Kúfa, which he had made his capital, by Ibn Muljam, a Khárijite conspirator.