In Syria, the siege of Damascus began on 21st August 634, and on 23rd August Abu Bakr was dead and Umar had become the Caliph though the army in Syria did not know of this change Khalid bin Walid was the Commander-in-Chief of the Muslim forces in Syria.
When the siege of Damascus began, the effort of Khalid was to isolate Damascus' so that no relief could reach it from any side. The road to Emessa lay open, and there was the danger that a relief force might come from Emessa. Khalid sent a detachment to take up its position at Bait Lihya ten miles from Damascus on the road to Emessa. The Commander of the detachment was instructed by Khalid to send out scouts to look for the approach of the Byzantine relief columns.
On the 9th of September 634, news was brought to Khalid that a large Byzantine army was marching from Emessa and was likely to reach Damascus within a couple of days. Khalid organised a mounted force of 5,000 men under the command of Zarrar. Zarrar was instructed to intercept the Byzantine force at Bait Lihya. Reaching Bait Lihya, Zarrar organised an ambush near "Thaniyyat-ul-Uqab"-the pass of the Eagle.
When the Byzantine army reached the pass, Zarrar ordered the attack. The Byzantines were prepared for the attack, and they deployed themselves in battle formation almost immediately. In the battle that ensued many Byzantines were killed, and the rest of the Byzantine army fled from the bartlefield. The Byzantines were, however, able to capture Zarrar alive. The loss of Zarrar had a depressing effect on the Muslim forces. The command was taken over by Rafie, and word was sent to Khalid for further help.
Leaving the command of Damascus to Abu Ubaida, Khalid set off to Bait Lihya with his mobile guard of 4,000 horse. As Khalid approached the battle-field, he saw a Muslim rider with a masked face gallop off towards the Byzantine front. This warrior would kill a number of the soldiers of the enemy, and then withdraw. He would after some time pounce upon the enemy once again and kill every one who came his way. Khalid wanted this warrior to tell him who he was. The warrior, however, dashed to the front again. As he returned from the attack after killing a number of the enemy, Khalid wanted the warrior to halt and identify himself. The warrior said "I am Khaula, sister of Zarrar. My brother has been captured by the Byzantines, and I am dashing against the enemy with a view to liberating Zarrar". Khalid praised the young girl for her bravery, and assured her that he would have her brother rescued.
Khalid launched the attack against the Byzantines with full force and by mid-day the Byzantines began to withdraw under the pressure of the Muslims. The scouts brought the news that they had seen a contingent of 100 Byzantines riding to Emessa with a half-naked man in their midst tied to his horse. Khalid ordered Raf'e to take one hundred picked horsemen, move forward along the flank of the Byzantines, get to the Emessa road, and intercept the escort taking Zarrar to Emessa. Raf'e set off at once on the mission with one hundred horsemen. Khaula accompanied the party.
Raf'e and his party got to the Emessa road at a point where the Byzantine escort had not yet reached, and there lay in ambush. When the Byzantines arrived at the spot, the Muslims fell on the Byzantines, killed most of them, and set Zarrar free.
Under the unrelenting pressure of the Muslims the force sent for the relief of Damascus was forced to retreat to Emessa in a state of disorder. As Zarrar came back to the camp of Bait Lihya, Khalid was much pleased to meet him. Khalid thanked Raf'e and Khaula for their services in freeing Zarrar. Khalid had a mind to pursue the fleeing force of the Byzantines, but he could not do so as his presence was required at Damascus. Khalid left a detachment at Bait Libya, and himself along with his mobile guard returned to Damascus.