and the forces of Mus'ab ibn al-Zubayr, governor of Iraq for his brother, the Mecca-based rival caliph Abd Allah ibn al-Zubayr.

When the battle started, most of Mus'ab's troops refused to fight, having secretly switched allegiance to Abd al-Malik, and Mus'ab's main commander, Ibrahim ibn al-Ashtar, was killed in action. Mus'ab was slain