Battle of Siffin-Mu'awiya, governor of Syria, claims the caliphate

In Syria, disorder and incitement to commotion continued unabated.

Uthman's shirt, besmeared with his blood and the chopped-off fingers of his wife, Naila, were exhibited from the pulpit. In this manner, Muawiya raised the entire country of Syria against Ali. Ultimately, both the parties, opposed to each other, converged on Siffin where their armies pitched their camps in 37/657. Even at this stage, Ali sent three men, viz. Bashir bin Amr bin Mahz Ansari, Saeed bin Qais Hamdani, and Shis bin Rabiee Tamini to Muawiya to induce him to settle for union, accord and coming together. According to Tabari (5h vol., p. 243), Muawiya replied that, "Go away from here, only the sword will decide between us."

With an army of some 80,000 strong, mainly recruited from Iraq, Ali set out from Kufa, planning to march through upper part of Iraq and invade Syria from the north. Ali, then pushed on to Raqa, on the left bank of the Euphrates. Here his troops came across the Syrian vanguard but it withdrew without engagement. The next problem was how to cross the river. Ali wanted to construct a bridge of boats, but the people of Raqa were hostile. It was only after Ali's general, Ashtar, had threatened them with death that they consented to help in building the bridge which was completed under the great difficulties. Ali's men then advanced along the right bank of the river in the direction of Aleppo. At Sur-Rum they had a brief skirmish with a Syrian outpost before they reached the plain of Siffin, where they found Muawiya's forces drawn up in strength and waiting for them.