Battle of Bosra The Battle of Bosra was fought in 634 between the Rashidun Caliphate army and the Byzantine Empire for the possession of Bosra , in Syria . The city , then capital of the Ghassanid kingdom , a Byzantine vassal , was the first important one to be captured by the Islamic forces . The siege lasted between June and July 634 . Background . Caliph Abu Bakr sent his four corps under Amr ibn al - A ' as , Abu Ubaidah ibn al - Jarrah , Shurahbil bin Hasana and Yazid bin Abu Sufyan and appointed for them different districts of Syria to capture . They were unable to get significant success in their goals and were in great pressure because of concentration of the Byzantine army at Ajnadayn . Abu Bakr therefore decided to send Khalid ibn Walid , The conqueror of Iraq , to Syria to command the Rashidun army there . Khalid ibn Walid reached Syria and capturing town to town he finally reached the city of Bosra in June 634 A . C . According to his instructions Abu Ubaidah ibn al - Jarrah who had already occupied the District of Hauran which lay north - east of the river Yarmuk , was to remain at his position until Khalid arrived at Bosra . Abu Ubaidah ibn al - Jarrah had three corps of the Muslim army under his command - his own , Yazid ' s and Shurahbil ' s , but he had fought no battles and captured no towns . One place which worried him a great deal was Bosra , a large town which was the capital of the Ghassanid Kingdom . It was garrisoned by a strong force of Byzantine and Christian Arabs under the command of Roman officers . While Khalid was clearing the region of Eastern Syria , Abu Ubaidah came to know that he would come under Khalid ' s command upon the latter ' s arrival . He decided to take Bosra quickly . He therefore sent Shurahbil with 4 , 000 men to capture Bosra . Shurahbil marched to Bosra , the garrison of which withdrew into the fortified town as soon as the Muslims appeared in sight . This garrison consisted of 4 , 000 soldiers , but expecting that more Muslim forces would soon arrive and that Shurahbil ' s detachment was only an advance guard , it remained within the walls of the fort . Shurahbil camped on the western side of the town , and positioned groups of his men all round the fort . For two days nothing happened . The following day , as Khalid ibn al - Walid set out on the last day of his march to Bosra , the garrison of the town came out to give battle to the Muslims outside the city . Both forces formed up for battle ; but first there were talks between Shurahbil and the Roman commander , at which the Muslim offered the usual choices : Islam , tribute , or the sword . The Romans chose the sword , and in the middle of the morning the battle began . For the first two hours or so the fighting continued at a steady pace with neither side making any headway ; but soon after midday , the superior strength of the Romans began to tell and the battle turned in their favors . The Romans were able to move forces around both Muslim flanks , and the fighting increased in intensity . The temper of the Muslims became suicidal as the real danger of their position became evident and they fought ferociously to avoid encirclement , which appeared to be the Roman design . By early afternoon the Roman wings had moved further forward , and the encirclement of Shurahbil ' s force became a virtual certainty . Then suddenly the combatants became aware of a powerful force of cavalry galloping in mass towards the battlefield from the northwest . Khalid was about a mile from Bosra when the wind carried the sounds of battle to him . He immediately ordered the men to horse , and as soon as the cavalry was ready , led it a gallop towards the battlefield . But Khalid and the Romans never met . As soon as the Romans discovered the arrival of the Muslims Cavalry , they broke contact from Shurahbil and withdrew hastily into the fort . The Muslims under Shurahbil came to regard this occurrence as a miracle : the Khalid had been sent to save them from destruction ! The battle . The next morning , the Byzantine garrison again came out of the fort to give battle . The shock of Khalid ' s arrival the previous day had now worn off , and seeing that the combined strength of the Muslims was about the same as their own , the Romans decided to try their luck again . They also hoped to fight and defeat the Muslims before they could get a rest after their march . The two armies formed up for battle on the plain outside the town . Khalid kept the center of the Rashidun army under his own command , appointing Rafay bin Umayr as the commander of the right wing and Dharar bin Al Azwar as the commander of the left wing . In front of the center , he placed a thin screen under Abdur - Rahman bin Abu Bakr ( son of the Caliph Abu Bakr ) . At the very start of the battle , Abdur - Rahman dueled with the Roman army commander and defeated him . As the Roman general fled to the safety of the Roman ranks , Khalid launched a general attack along the entire front . For some time the Romans resisted bravely , while the commanders of the Muslim wings played havoc with the opposing wings , especially Dharar , who now established a personal tradition which would make him famous in Syria - adored by the Muslims , and dreaded by the Romans . Because of the heat of the day , he took off his coat of mail ; and this made him feel lighter and happier . Then he took off his shirt and became naked above the waist . This made him feel even lighter and even happier . In this half naked condition Dharar launched his assaults against the Romans and slaughtered all who faced him in single combat . Within a week , stories of the Naked Champion would spread over Syria , and only the bravest of Romans would feel inclined to face him in combat . After some fighting , the Byzantine army broke contact and withdrew into the fort . At this time Khalid was fighting on foot in front of his centre . As he turned to give orders for the commencement of the siege , he saw a horseman approaching through the ranks of the Muslims . It was Abu Ubaidah ibn al - Jarrah and with him was a yellow standard and is believed to have been the standard of the Muhammad at the Battle of Khaybar . This was the man who had been placed under the command of Khalid . He gave that standard to Khalid ibn al - Walid and he took it saying . The Muslims now laid siege to Bosra . The Byzantine commander lost hope , for he knew that most of the available reserves had either moved or were moving to Ajnadayn , and doubted that any help would be forthcoming . After a few days of inactivity , he surrendered the fort peacefully . The only condition Khalid bin Walid imposed on Bosra was the payment of the tribute . This surrender took place in about the middle of July 634 . Romanus ' s conversion to Islam . Another version of the battle of Bosra records the conversion to Islam one of the commanders of the Byzantine force , Romanus . The conversion occurred after the arrival of Khalid ' s reinforcements to Bosra during pre - battle melee . This conversion made night infiltration into the Bosra fortification possible under the guide of Romanus , hence enabling the Muslim army to inflict disproportionate numbers of casualties when compared to their own among the Byzantines forces . The battle was preceded by a call for personal combat between the commanders of the armies . Khalid stepped forward from the Muslim ranks and out of the Byzantine ranks their commander Romanus stepped forward . Before dueling , Khalid offered Islam to Romanus , and surprisingly enough , Romanus after asking a few questions about Islam , declared the article of faith and became a Muslim . He crossed over to the Muslim camp . From the Muslim camp , Romanus addressed the Byzantines in the following terms : The conversion of Romanus to Islam unnerved the Byzantine forces , and instead of giving the fight , they withdrew to the city and shut the gates against the Muslims . That night , Romanus led a Muslim detachment to a subterranean passage under the ramparts of the city . This contingent was led by Abdur Rahman , the son of Abu Bakr . This contingent entered the city through the underground passage and then dashing towards the city gates opened them for the main Muslim army to enter . The Muslim forces attacked right and left , raising the cries of " Allah - u - Akbar " . The Byzantines were slaughtered in thousands and the survivors laid down arms . The citizens of Bosra agreed to pay the jizya tax , and thereupon a peace pact was drawn up . Consequences of the conquest of Bosra were : The conquest of Bosra in the second week of July 634 was the first important victory gained by the Muslims in Syria . The Muslims lost 130 men in the battle , while the Byzantines suffered several thousand casualties . The conquest of Bosra opened , for the Muslims the gate for the conquest of Syria . Aftermath . Khalid bin Walid wrote to Caliph Abu Bakr , informing him of the progress of his operations since his entry into Syria , and sent one - fifth of the spoils which had been won during the past few weeks . Hardly had Bosra surrendered when an agent sent by Shurahbil to the region of Ajnadayn returned to inform the Muslims that the concentration of Roman legions was proceeding apace . Soon they would have a vast army of 90 , 000 imperial soldiers at Ajnadayn . Khalid ibn Walid ordered all the Muslim corps in Syria to concentrate at Ajnadayn and defeated the Byzantine army in the Battle of Ajnadayn .