Khalid's march to Damascus. From Busra, Khalid marched northward to Damascus. The Muslim forces occupied the outskirts of Damascus. Damascus was heavily guarded, and the Muslim force was too small to press the siege of a city like Damascus. After the defeat of Busra, the Byzantine emperor was much upset. He vowed vengeance and undertook preparations on a large scale to drive away the Muslims from the soil of Syria. Heraclius garrisoned all forts in Syria. He ordered a huge concentration of forces in the south at Ajnadein, west of Jerusalem.
Lifting the siege of Damascus. The Muslim scouts brought the intelligence that a Byzantine force over one hundred thousand strong had assembled at Ajnadein. That set Khalid thinking. If he pressed the siege against Damascus the danger was that the Byzantine army from Ajnadein might attack the Muslim army from the rear, and in that case the position for the Muslims would become very critical. Khalid accordingly changed his strategy, and decided to deal with the Ajnadein Byzantine forces in the first instance. In pursuance of this decision, the siege of Damascus was lifted and the Muslim forces were ordered to march to Ajnadein. Up to this time, the various Muslim forces in Syria were operating in different sectors. Khalid directed the integration of all the Muslim forces and required the entire Muslim army to assemble at Ajnadein.
Byzantine attack on the Muslims. When the siege of Damascus was lifted by the Muslims that emboldened the Byzantines. A Byzantine contingent with a force of six thousand horses and ten thousand-foot soldiers fell upon the Muslim rearguard as they were retreating from Damascus. So fierce and unexpected was the Byzantine attack that the Muslims had to give way. The Byzantines were able to capture a number of women who were in the Muslim camp.
Khaula. The Muslim women captured by the Byzantines were kept in a separate camp. The Byzantines intended to carry these women to Damascus after they had collected other booty. Among the women prisoners was a beautiful lady, Khaula, the sister of the Muslim commander Zarrar. Peter the commander of the Byzantine contingent was struck by her beauty and chose her for himself. Khaula was a firebrand lady of extraordinary courage. She exhorted her companions to muster courage and defy their capture. Her companions asked as to how they were to resist their captors when they were unarmed. Khaula asked them to get hold of the tent poles. They were required to keep close to one another, and to fall upon the Byzantine soldiers who came near them.
Some Byzantine soldiers tried to get hold of the Muslim women. The women struck them with tent poles, and smashed their skulls. Then Peter addressed Khaula from a safe distance "Surrender and I will see that you are not only safe, but that I make you the queen of my heart." Khaula retorted "You Byzantine dog, how can you dare marry a Muslim virgin. I will kill myself in the case of any such exigency." Peter ordered his men to surround the women and disarm them. The women were in a defiant mood, and would not allow any one approach them. Thereupon Peter ordered his soldiers to step forward with drawn swords.
Khalid's vengeance. When Khalid bin Walid who was leading the vanguard came to know of the disaster that had befallen his rearguard, he turned back and rushed to the relief of his men. Khalid struck with vengeance. The Byzantines were not only routed; they were massacred. Out of six thousand Byzantine horsemen, only one hundred escaped back to Damascus to tell the story of the disaster that had fallen them. When Peter and his men were stepping forward to overpower the Muslim women, Khalid, Zarrar, and other Muslim warriors arrived at the spot to the aid of the Muslim women. Peter thereupon turned to flee but was intercepted by Zarrar the brother of Khaula. Addressing Zarrar, Peter said, "She is your sister; I make you a present of her." Zarrar said that he accepted the present, and then in return he had to give him the point of his spear. Thereupon Zarrar struck off the head of Peter and impaled it on his lance.