under Khalid's command, pursued the Byzantine column via the shorter Emessa road and caught them in the northwest Beqaa Valley, just before they entered the mountains en route to Antioch at the Battle of Maraj-al-Debaj. Conquest of central Syria Soon after the appointment of Abu-Ubayda as commander in chief, he sent a small detachment to the annual fair held at Abu-al-Quds, modern day Abla, near Zahlé; east of Beirut. There was a Byzantine and Christian Arab garrison guarding that fair, the size of the garrison was miscalculated by the Muslim informants and it quickly encircled the small Muslim detachment. Before it would have been completely destroyed, Abu Ubayda, having received new intelligence, sent Khalid to rescue the Muslim army. Khalid reached there and defeated them in the Battle of Abu-al-Quds on 15 October 634 and returned with tons of looted booty from the fair and hundreds of Byzantine prisoners. With central Syria captured, the Muslims has given a decisive blow to the Byzantines. The communication between northern Syria and Palestine was now cut off. Abu Ubayda decided to march to Fahl (Pella), which is about below sea level, and where a strong Byzantine garrison and survivors of Battle of Ajnadayn were present. The region was crucial because from here the Byzantine army could strike eastwards and cut the communications line with Arabia. Moreover, with this large garrison at the rear, Palestine could not be invaded. Thus the Muslim army moved to Fahl. The Byzantine army was eventually defeated at the Battle of Fahl on 23 January 635 A.D. Battles for Emesa and the second battle of Damascus After the battle, which would prove to be a key to Palestine and Jordan, the Muslim armies split up. Sharjeel and Amr's corps moved south to capture Palestine. Meanwhile, Abu Ubayda and Khalid with a relatively larger corps moved north through Lebanon to conquer Lebanon and northern Syria. While the Muslims were occupied at Fahl, Heraclius, sensing the opportunity, quickly sent an army under General Theodore Trithyrius to recapture Damascus, where a small Muslim garrison had been left. Shortly after Heraclius dispatched this new army, the Muslims having finished the business at Fahl, were on their way to Emesa. The Byzantine army met the Muslims half way to Emesa, at Maraj-al-Rome. During the night Theodras sent half of his army towards Damascus to launch a surprise attack on the Muslim garrison Khalid's spy