Battle of Siffin was fought between forces of Muawiyah and Hazrat Ali. Seeing that the Medinites could not depose Ali, Muawiyah, who was now a powerful man in Syria, and had a strong army of his own, was head of the House of Umayyad, decided to try his luck against Ali. He claimed to be the avenger of Osman’s death.
It was not, he said, that Usman belonged to the clan of the Bani Umayyad, it was only that he was an innocent martyr and his blood cried for revenge. Muawiyah showed the blood-stained shirt of the martyred Usman to the people, seeking their support, and soon felt himself in a strong enough position to fight. Many people thought that it was a revival of the old rivalry between the Houses of Umayyad and Hashim, but were powerless to prevent it. Muawiyah’s army moved east. Ali moved north with his troops. The two armies met at Siffin which lay in north-eastern Syria. Muawiyah had a strong army, but Ali was the better general. Soon Muawiyah found that he could not win, so he thought of a ruse. He ordered his soldiers to tie their Quran to their lances and raise them in the air, which they did. Ali saw through his and told his army that it was a trick, but the soldiers could not cut down men who held up the Quran. The fighting ceased.
Muawiyah now proposed arbitration; he and Ali should each choose a nominee and leave the matter to them. Ali agreed, because he did not want any more bloodshed, but a number of people in this won camp were not pleased. They said that since Ali was in the right he should not leave such matter to the arbitrations of man. They also declared that Ali was making a big mistake and would lose their support. After this, they decided to withdraw from Ali’s side. Others said that by accepting arbitration Ali had lost all prestige because he thus accepted Muawiyah as his equal although Muawiyah was his subordinate and now a rebel, as he had risen against the Caliph.
What was worse, Ali made a wrong choice. Muawiyah selected a friend of his, the astute Amr ibn al-As, as his nominee; Ali nominated a neutral, Musa al-Ashari. The arbitrators made a curious decision; they announced that both Muawiyah and Ali should resign. This was really a condemnation of Ali, because Muawiyah was a subordinate who had already rebelled against the Caliph and could not continue in his office. So the verdict was in reality against Ali and he did not accept it. For that matter, neither did Muawiyah. Both armies’ retreated, and the same state of affairs continued. Ali’s loss, however, was double, asl Amr ibn al-As openly accepted Muawiyah as the de facto Caliph.