The Battle of Maskin, also known as the Battle of Dayr al-Jathaliq from a nearby Nestorian monastery, was a decisive battle of the Second Fitna (680s-690s). It was fought in mid-October 691 near present-day Baghdad on the western bank of the river Tigris, between the army of the Umayyad caliph Abd al-Malik ibn Marwan 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. At the beginning of the battle, 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 soon afterward, resulting in the Umayyads' victory and recapture of Iraq, which opened the way for the Umayyad reconquest of the Hejaz (western Arabia) in late 692.