Siege of Damascus ( 634 ) The Siege of Damascus ( 634 ) lasted from 21 August to 19 September 634 AD before the city fell to the Rashidun Caliphate . Damascus was the first major city of the Byzantine ( Roman ) empire to fall in the Muslim conquest of Syria . The last of the Roman - Persian Wars ended in 627 , when Heraclius concluded a successful campaign against the Persians in Mesopotamia . At the same time , Mohammad united the Arabs under the banner of Islam . After his death in 632 , Abu Bakr succeeded him as the first Rashidun Caliph . Suppressing several internal revolts , Abu Bakr sought to expand the empire beyond the confines of the Arabian Peninsula . In April 634 , Abu Bakr invaded the Byzantine Empire in the Levant and decisively defeated a Byzantine army at the Battle of Ajnadayn . The Muslim armies marched north and laid siege to Damascus . The city was taken after a monophysite bishop informed Khalid ibn al - Walid , the Muslim commander in chief , that it was possible to breach city walls by attacking a position only lightly defended at night . While Khalid entered the city by assault from the Eastern gate , Thomas , commander of the Byzantine garrison , negotiated a peaceful surrender at the Jabiyah gate with Abu Ubaidah , Khalid ' s second in command . After the surrender of the city , the commanders disputed the terms of the peace agreement . The commanders finally agreed that the peace terms given by Abu Ubaidah would be met . Although he acquiesced to the peace terms , three days after the surrender of the city Khalid chased after the Damascan refugees towards Antioch and defeated them in battle six days later , near present day Al Jayyad . Background . In 611 , during the Byzantine - Sassanid War of 602 - 628 , Heraclius became the emperor of the Byzantine Empire after overthrowing Phocas . While Heraclius focused his attention on the internal affairs of his empire , the Sassanid Persians conquered Mesopotamia , overran Syria in 611 AD , and entered Anatolia to occupy Caesarea Mazaca . In 612 , Heraclius expelled the Persians from Anatolia . In 613 , he launched a counter offensive against Syria , but was decisively defeated . Over the next decade , the Persians conquered Palestine and Egypt and Heraclius rebuilt his army , preparing for a new offensive , which he launched in 622 . He achieved substantial victories over the Persians and their allies in the Caucasus and Armenia . In 627 , he launched a daring winter offensive against Persia in Mesopotamia , and won a decisive victory at the Battle of Nineveh . This victory threatened the Persian capital city of Ctesiphon . Discredited by this series of disasters , Khosrau II was killed in a coup led by his son Kavadh II , who at once sued for peace , agreeing to withdraw from all occupied territories of the Byzantine empire . Heraclius restored the True Cross to Jerusalem with an elaborate ceremony in 629 . In Arabia , the Prophet Mohammad had united most of Arabia under a single religious and political authority . When Mohammed died in June 632 , Abu Bakr was elected to the newly - formed office of Caliph , becoming Mohammad ' s political and religious successor . Several Arabic tribes revolted against Abu Bakr . In the Ridda wars ( Arabic for the Wars of Apostasy ) , Abu Bakr quelled the revolt . By 633 , Arabia was firmly united under the central authority of the Caliph in Medina . In 633 , Abu Bakr initiated a war of conquest against the neighboring Sassanian and Byzantine empires . After a successful conquest of the Persian province of Iraq , Abu Bakr ' s confidence grew and in April 634 his armies invaded the Byzantine Levant from four different routes . These armies proved to be too small for the task , necessitating reinforcements from Iraq , led by Abu Bakr ' s capable general Khalid ibn Walid Crossing the desert , Khalid ibn Walid entered Syria from an unexpected route in a bold move . He attacked and overthrew the Byzantine defenses of Levant and quickly captured the Ghassanid capital city of Bosra . In July 634 , the Muslim army under Khalid ' s command defeated another Byzantine army in the Battle of Ajnadayn . After clearing their southern flank , the Muslims laid siege to Damascus . Siege site . Strategically located , Damascus attracted merchants from all over the world . The city was known as the paradise of Syria . The fortifications matched its importance . The main part of the city was enclosed by a massive high wall . The fortified city was approximately long and wide . The wall had six gates : Although the River Barada ran along the north wall of Damascas , it was too shallow to be of defensive importance . At the time of the Syrian campaign , the Byzantine Commander of Damascus was Thomas , son - in - law of Emperor Heraclius . A devout Christian , he was known for his courage and skill at command , and also for his intelligence and learning . Dispositions . Seventh - century Muslim armies had no siege equipment , and typically employed siege tactics only when there were no other options . Without the necessary siege equipment , armies of the early Muslim expansion would lay surround a city , denying it supplies until the city ' s defenders surrendered . Meanwhile any chance of breaking into the city would be availed , if possible , using stealth and espionage . Muslim armies would usually isolate the city from the rest of the region and deploy scouts along vital routes . To isolate Damascus , Khalid cut the lines of transportation and communication to northern Syria . To the west , a detachment of cavalry at Fahal occupied the attention of the Byzantine garrison . This detachment also protected the Muslim supply lines to Madinah . Thus this cavalry detachment functioned as the rearguard of the Muslim forces on the Syrian front . Another detachment was sent on the road to Emesa to take up a position near Bait Lihya , approximately from the city . Its instructions were to reconnoiter for any Byzantine relief columns . If unable to defeat or repel a Byzantine rescue effort , the detachment commander was instructed to send for reinforcements from Khalid . Having isolated Damascus , Khalid ordered his army to surround the city on August 21 , 634 ( the 20th of Jamadi - ul - Akhir , 13 Hijri ) . The corps commanders were instructed to repel any Byzantine attack from the respective gates , and seeking assistance in the case of heavy attack . Dharar bin al - Azwar commanded 2 . 000 horsemen from the mobile guard to patrol in the empty areas between the gates at night and to reinforce any corps attacked by the Byzantines . The following Muslim generals held the siege of the six gates of the Damascus . Each commander at the gate had 4 , 000 – 5 , 000 forces under his command : Khalid placed the main body of his forces under the command of Rafay bin Umayr at the eastern gate . He established his headquarters a short distance away from the eastern gate in a monastery , known since then as " Deir al Khalid " , the monastery of Khalid . Khalid ' s army had encircled the city , halting the flow of supplies into Damascus while the Ghouta of Damascus provided the Muslim army with all the supplies Khalid needed for his men and their mounts . Byzantine relief . Emperor Heraclius was at Antioch at the beginning of the siege and on September 9 , 634 , he dispatched a relief force , thought to have numbered around 12 , 000 men . Scouts posted on the road from Emesa to Damascus reported the approach of a Byzantine army . Upon hearing this news , Khalid sent Rafay bin Umayr with 5 , 000 troops . They met north of Damascus at Uqab Pass ( Eagle Pass ) on the Damascus - Emesa road . That force proved insufficient and soon surrounded by the Byzantine troops . However before the Byzantines could defeat the Muslim detachment , Khalid arrived with another column of 4 , 000 men and routed them . It has since come to be known as Battle of the pass of Uqab . The Muslim siege forces had been weakened by the withdrawal of 9 , 000 men to repel the Byzantine relief force . If the Byzantine garrison had sallied out against the Muslim army , historians suspect the defenders would have broken through the Muslim lines and lifted the siege . Understanding the danger of the situation , Khalid hurriedly returned to Damascus . First Byzantine attack . After realizing that no reinforcements would come , Thomas decided to launch a counter offensive . Early in the third week of September 634 , Thomas drew men from all sectors of the city to form a force strong enough to break through the Gate of Thomas . He was there faced by Shurahbil with his corps of about 5 , 000 men . The Byzantine attack began with a concentrated shower of arrows against the Muslims . The Byzantine infantry , covered by the archers on the wall , rushed through the gate and fanned out into battle formation . Thomas himself led the assault . During this action , Thomas was struck in his right eye by an arrow . Unsuccessful in breaking the Muslim lines , the Byzantines retreated back to the fortress . The wounded Thomas is said to have sworn to take a thousand eyes in return . He ordered another great sortie for that night . Second Byzantine attack . This time Thomas planned to launch simultaneous sorties from four gates . The main sector was to be again the Thomas gate , to take full advantage of the exhausted Muslim corps stationed there . The attacks from the other gates — Jabiya Gate , the Small Gate and the Eastern Gate — were intended to tie down the other Muslim corps so that they could not aid Shurhabil ' s corps at the Thomas gate . At the Eastern Gate , Thomas assembled more forces than at the other gates , so that Khalid would be unable to move to Shurahbil ' s assistance and take command in that decisive sector . Thomas ' attack at several gates also gave more flexibility to the operation : if success were achieved in any sector other than the Gate of Thomas , such success could be exploited by sending troops to that sector to achieve the breakthrough . Thomas ordered Khalid to be taken alive . After some hard fighting at the Jabiya Gate , commander Abu Ubaidah and his men , repulsed the sally and the Byzantines hastened back to the city . The battle was intense at the Small Gate , which was guarded by commander Yazid and his men . Yazid had fewer troops but Dharar came to Yazid ' s aid with his 2 , 000 cavalry of the Mobile Guard . The cavalry attacked the flank of the Byzantine sortie force and repulsed the sally . At the East Gate , the situation also became serious , for a larger Roman force had been assigned to this sector . Rafay was unable to withstand their attacks . The timely arrival of Khalid with his reserve of 400 veteran cavalry and his subsequent attack on the Roman flank , marked the turning point in the sally at the Eastern Gate . The heaviest fighting occurred at the Thomas gate , where Thomas again commanded the sally in person . After intense fighting , Thomas , seeing that there was no weakening in the Muslim front , decided that continuing the attack would be fruitless and would lead to even heavier casualties among his men . He ordered a withdrawal and the Romans moved back at a steady pace , during which they were subjected to a concentrated shower of arrows by the Muslims . This was the last attempt by Thomas to break the siege . The attempt had failed . He had lost thousands of men in these sallies , and could no longer afford to fight outside the walls of the city . Khalid ' s attack . On September 18 ( 19 Rajab , 13 Hijrah ) , a disaffected monophysite bishop of Damascus sent a Greek named Jonah to inform Khalid about a festival celebration in the city that night . The festivities offered Khalid an opportunity to capture the city in a surprise attack on the relatively lightly defended walls . In return , he requested immunity for himself and his fiance . According to Muslim chronicles , she was still not handed over to him because of the arrival of the Muslim army that was to besiege Damascus , and according to the narrations he came to Khalid with this information only to get his beloved wife soon . Jonah also converted to Islam . With no time to make a coordinated plan of attack for the whole army , Khalid decided to storm the East Gate himself . He , Qa ' qa ibn Amr , and Mazur ibn Adi climbed the wall hand - by - hand from the side of the gate . This part of the wall was the strongest , no guard was stationed at the top . They secured ropes to the wall and dropped them to 100 selected soldiers waiting at the base . Leaving a few men to assist the climbers , Khalid descended into the city , killing the guards at the inside of the East Gate . Khalid and Qa ' qa flung the gate open and the remainder of Khalid ' s men entered the city . An intense battle ensued . When Thomas saw that the rest of the army did not move from the other gates , he assumed first that only Khalid ' s army had entered the city and second that the other corps commanders were unaware of this sudden attack . Muslim practice was specific : if a city surrendered , the inhabitants would be spared , but if a city resisted , the resisters would be killed . Thomas tried to save Damascus for one last time . He sent envoys to the Jabiya Gate to talk with Abu Ubaidah , the second in command to Khalid , and offered to surrender the fort peacefully and to pay the Jizya . Abu Ubaidah , who was well - known for his peace - loving nature , accepted the terms , thinking that Khalid would also agree . The news was sent to all the corps commanders . After dawn Abu Ubaidah entered Damascus from Jabiyah gate and the other commanders from their respective gates , while Khalid ' s corps was still battling in the city from the East Gate . Abu Ubaidah marched peacefully with his corps , accompanied by Thomas , Harbees , several dignitaries , and the bishops of Damascus , toward the center of city . From the East Gate , Khalid and his men fought their way towards the center of Damascus , killing all who resisted . The commanders met at the Church of Mary in the center of the city . Capture of the city . Khalid argued that he had conquered the city by force . Abu Ubaidah maintained the city had capitulated , through the peace agreement between him and Thomas . The corps commanders discussed the situation , and reportedly told Khalid that the peace agreement must be honored . Their rationale had logic : if the Romans in Syria heard that the Muslims had given a guarantee of safety to a surrendered city and then had slaughtered those whose safety had been guaranteed , no other city would ever surrender to the Muslims . This would make the task of conquering Syria immeasurably more difficult . Khalid , though not happy , agreed to honor the peace agreement . The terms of the peace agreement were that no one would be enslaved , no harm would be done to the temples , nothing would be taken as booty and that safe passage was given to Thomas , Harbees , and every citizen of Damascus who was not willing to live under Muslim rule . The peace agreement also stated that the peace would end after three days and that the Muslims could attack after these three days without violating the agreement . The following pact was drawn up and signed by Khalid bin Walid : In the name of Allah , the Beneficent , the Merciful . This is given by Khalid bin Al Waleed to the people of Damascus . When the Muslims enter , they ( the people ) shall have safety for themselves , their property , their temples and the walls of their city , of which nothing shall be destroyed . They have this guarantee on behalf of Allah , the Messenger of Allah , the Caliph and the Muslims , from whom they shall receive nothing but good so long as they pay the Jizya . Aftermath . The Greek , Jonah , who had helped Khalid enter the city by the East Gate , showed him a short - cut to Antioch . Leading a cavalry regiment , Khalid caught up with a convoy of Byzantine refugees from Damascus at the sea , near Antioch . The three - day truce had passed ; Khalid ' s cavalry attacked the convoy during a heavy rain . In the subsequent battle , Khalid reportedly killed both Thomas and Harbees in a duel . After the Battle , known as the Battle of Marj - ud - Deebaj ( Battle of Brocade Meadow ) , the Muslims took a great amount of brocade as booty . In addition , Thomas ' wife , the daughter of Heraclius , was captured . According to chronicles , the Greek man Jonah , who guided Khalid on the short cut to Antioch , got his fiance , but she committed suicide . Khalid offered Jonah the daughter of Emperor Heraclius , whom he refused . Khalid sent her back to her father . Jonah died two years later in the Battle of Yarmuk . Caliph Abu Bakr died in Madinah , making Umar his successor . Umar removed Khalid from command of the Muslim army and appointed Abu Ubaidah as the new commander in chief . In later years , following the Battle of Yarmuk , the Rashidun Caliphate annexed the whole Levant , followed by the conquest of Antioch in 638 . By 639 , the Byzantines had lost Armenia and Mesopotamia . Emperor Heraclius concentrated on the defenses of Egypt and Anatolia , creating a buffer - zone in Anatolia west of Caesarea by abandoning all the Byzantine fortifications there . The Muslims never invaded Anatolia . However , by 642 the Byzantines lost Egypt and Tripolitania to the Caliphate . While the Arabs administered the city of Damascus , the population of Damascus remained mostly Christian — Eastern Orthodox and Monophysite — with a growing community of Arab Muslims from Makkah , Madinah , and the Syrian Desert . The city was chosen as the capital of Islamic Syria . Its first Muslim governor was Yazid ibn Abu Sufyan , one of the commanders of the Muslim army that captured the city . Yazid died of plague in 640 and his younger brother , Mu ' awiya I , succeeded him . After the murder of the last Rashidun Caliph , Caliph Ali in 661 , Mu ' awiya installed himself as the caliph of the Islamic empire founding the Umayyad dynasty . Damascus subsequently became the capital of the Ummayad Caliphate and all of the surplus revenue of the Ummayad Caliphate ' s provinces were forwarded to the treasury of Damascus . Arabic was also established as the official language , giving the Arab minority of the city an advantage over the Greek - speaking Christians in administrative affairs . Trade and economics prospered in the city and under the Umayyads , Damascus remained one of the most dazzling cities of the world , until in 750 , when it fell to the Abbasids . On August 25 , 750 , the Abbasids , having already beaten the Umayyads in the Battle of the Zab in Iraq , conquered Damascus after facing little resistance . With the heralding of the Abbasid Caliphate , Damascus became eclipsed and subordinated by Baghdad , the new Islamic capital .