After the battle of Siffin (657) arbitration was resorted to for the settlement of the rival claims. By a trick `Ali was deposed (658), and the Omayyad dynasty was established with its capital at Damascus.
They compelled him suddenly to break off the battle of Siffin, which he was apparently on the point of gaining over Moawiya, because the Syrians fastened copies of the Koran to their lances to denote that not the sword, but the word of God should decide the contest (see further below, B.
The battle at Siffin (657), near the Euphrates, which lasted two months and consisted principally in, sometimes bloody, skirmishes, with alternate success, ended by the well-known appeal to the decision of the Koran on the part of Moawiya.
Ali, however, had first to deal with the insurrection of the Kharijites, who condemned the arbitration which followed the battle of Siffin as a deed of infidelity, and demanded that Ali should break the compact (see above, A.4).
Not a few of his former partisans went over to Moawiya, as already had happened before the days of Siffin, amongst others Ali's own brother Vigil.
A prolonged battle took place in July 657 in the plain of Siffin (Suffein), near the Euphrates; the fighting was at first, it is said, in favour of Ali, when suddenly a number of the enemy, fixing copies of the Koran to the points of their spears, exclaimed that "the matter ought to be settled by reference to this book, which forbids Moslems to shed each other's blood."