Soon the Muslims heard of a gathering of 90,000 Byzantine army (Eastern Roman army) at Ajnadayn, about southwest of Jerusalem. All the divisions of the Muslim army, about 32,000 in number, joined Khalid at Ajnadayn on 24 July 634. Under the command of Khalid ibn al-Walid the Muslims defeated the Byzantine army there on 30 July 634 at the Battle of Ajnadayn. After one week, Abu Ubaidah, along with Khalid, moved towards Damascus. On their way to Damascus, they defeated another Byzantine army at the Battle of Yakusa in mid-August 634. Caloiis and Azrail, the governor of Damascus, led another army to stop Khalid's corps but they were also defeated in the battle of Maraj-al-Safar on 19 August 634.