Battle of Maraj - al - Debaj Battle of Marj - ud - Deebaj was fought between the Byzantine army , survivors from the conquest of Damascus , and the Rashidun Caliphate army in September 634 . It was a successful raid after three days of armistice , on the Byzantine survivors of the conquest of Damascus . Background . Damascus was conquered by the Rashidun army after a siege lasting about one month , from 21 August to 19 September 634 A . D . It was the first stronghold of the Byzantine empire conquered by Muslims during the Muslim conquest of Syria . The Byzantine commander Thomas , commander in chief and governor of Damascus and son in law of Emperor Heraclius , after hearing that Muslim troops had entered Damascus at the Eastern gate , wisely tricked the Muslim corps commanders at the other gates by suing for peace . The peace offer then was accepted by them . After the trick was unveiled the Muslim commanders advised Khalid ibn Walid that the peace agreement should be kept , because if the Romans in Syria heard that the Muslims had given a guarantee of safety and then slaughtered those whose safety had been guaranteed , no other city would ever surrender to the Muslims , and that would make the task of conquering Syria immeasurably more difficult . Khalid was not happy , but he agreed . A Greek Muslim " Jonah " by name , suggested Khalid to chase the Byzantines after the three days of armistice agreed upon was over . He gave his services to guide Khalid through a short cut route to reach them as soon as possible . According to Muslim chronicles this Greek man Jonah was in love with a girl who was his fiance and was to be married with him but when the Muslim army launched the siege of the city , the marriage was postponed until peace was restored . Frustrated with the long siege and delayed marriage Jonah came to Khalid and informed him about a weak post on the Wall of Damascus where that night security was to be weak . Khalid with other Muslim warriors climbed up the wall and opened the gates and the Muslim army positioned at the Eastern gate entered the city . Jonah ' s fiance on hearing of his conversion to Islam broke the engagement and decided to move with the Byzantines to Antioch . This prompted Jonah once again to go to Khalid . The plan of Jonah was accepted by Khalid : they would launch a pursuit after three days , when the three days grace period was over . The Mobile Guard would dash out in pursuit and go at breakneck speed . On Jonah ' s suggestion it was decided that all would be dressed like local Arabs , so that any Roman units encountered on the way would mistake them for such and not intercept their movement . The battle . The route taken by the Mobile guard is not recorded . It is stated by the historian Waqidi that the Muslims caught up with the convoy a short distance from Antioch , not far from the Mediterranean Sea , on a plateau beyond a range of hills called Jabal Ansariya , in Northern Syria . Due to a heavy downpour , the Byzantine convoy had dispersed on the plateau , seeking shelter from the weather , while their goods lay all over the place . So many bundles of brocade lay scattered on the ground that this plain became known as Marj - ud - Debaj , i . e . the " Meadow of Brocade " , and for this reason the action described has been named the Battle of Marj - ud - Deebaj , or the Battle of Meadow of Brocade . Jonah and other scouts established the location of the convoy without being spotted and they brought back sufficient information for Khalid to plan his attack . Khalid arranged a skillful plan of attacking the Byzantines from four different sides . First a cavalry regiment of 1000 warriors would attack the Byzantines from their rear in the south , subsequently followed by an attack of a cavalry regiment 1000 warriors from the east , north ( thereby blocking their retreat to Antioch ) and finally from the west to encircle them completely . It all happened as Khalid had planned . The Byzantines received their first indication of the presence of the Muslim army when a regiment of 1000 cavalry came charging at them from the south , along the road from Damascus , led by the Zirrar ibn Azwar . Half an hour later another cavalry regiment of 1000 warriors led by Raafe bin Umair , appeared from the east and struck the Byzantine ' s right flank . Within the span of half an hour another cavalry regiment of 1000 warriors led by Abdu ' l - Rahman ibn Abu Bakr ( " Son of Caliph Abu Bakr " ) from the north , struck the Byzantines at the rear thus blocking their way to retreat north towards Antioch . After about another half an hour later the final Muslim cavalry of 1000 warriors led by Khalid ibn Walid appeared from the west and attacked the Byzantine ' s left flank . Now the Byzantines were totally encircled by the Muslim ' s cavalry . Khalid personally killed Thomas ( " Son in Law of Emperor Heraclius " ) and Harbees in a duel . After some more fighting , Roman resistance collapsed . Since the Muslims were too few to completely surround the Byzantine army and the fighting had become confused as it increased in violence , thousands of Byzantines were able to escape and make their way to safety . But all the booty and a large number of captives , both male and female , fell to the Muslims . According to a chronicle Jonah found his beloved . He moved towards her to take her by force ; but she draw a dagger from the folds of her dress and killed herself . As she lay dying , Jonah sat beside her and swore that he would remain true to the memory of the bride he was not destined to possess , and would not look at another girl . When Khalid came to know about this he offered Jonah the daughter of Emperor Heraclius , the former wife of Thomas who died in the battle that day in a duel with Khalid . Jonah rejected the proposal . Jonah died a few years later in the Battle of Yarmouk . Aftermath . The historian Waqidi writes that on their way back to Damascus , Emperor Heraclius sent an ambassador to ask Khalid to return his daughter . The ambassador gave Khalid the letter from the Emperor which read as follows : Khalid said to the ambassador : The ambassador took the daughter of Heraclius , and returned to Antioch . The return of the Mobile Guard loaded with spoils was greeted with joy by the Muslims at Damascus . The whole operation from pursuit to the return of the Mobile guard had taken 10 days . They returned on October 1 , 634 . Upon his return Khalid was informed of the death of Caliph Abu Bakr and the succession of Umar as the new caliph . Umar deposed Khalid from his command and appointed Abu Ubaidah ibn al - Jarrah as the new commander in chief .