When war between Ali and Muawiyah became inevitable, preparations for a show down were made by both the sides. Ali managed to raise an army 90,000 strong. It included men from Kufa, Iraq, Basra and Madina. Ali made Malik Ashtar the Commander-in-Chief of his forces. The army was divided into a number of commands and each command had its own commander.
In the correspondence that was exchanged between the two sides, option was given to Ali to lead the force to Syria or let the Syrian forces come to Iraq Ali opted to lead his forces to Syria. In March 657, Ali set out from Kufa at the head of his army. From Rufa the army proceeded to Madina. Here more troops joined the army of Ali. From Madina Ali set out for Syria. His plan was to march through Upper Mesopotamia and invade Syria from the north. The advance guard of the army advanced along the western bank of the Euphrates. The main army under Ali advanced up to the Tigris, and thereafter entered the Mesopotamian desert.