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The Battle of Yarmouk was a major battle between the Muslim forces of the Rashidun Caliphate and the armies of the Eastern Roman-Byzantine Empire. The battle consisted of a series of engagements that lasted for six days in August 636, near the Yarmouk River, along what is today the border between Syria and Jordan, south-east of the Sea of Galilee. The result of the battle was a complete Muslim victory which ended Byzantine rule in Syria. The Battle of Yarmouk is regarded as one of the most decisive battles in military history, and it marked the first great wave of Islamic conquests after the death of Muhammad, heralding the rapid advance of Islam into the then Christian Levant.
In order to check the Muslim advance and to recover lost territory, Emperor Heraclius had sent a massive expedition to the Levant in May 636. As the Byzantine army approached, the Muslims retreated from Syria and regrouped all their forces at the Yarmouk plains close to Arabia where, after being reinforced, they defeated the numerically superior Byzantine army. The battle is also considered to be one of Khalid ibn al-Walid's greatest military victories. It cemented his reputation as one of the greatest tacticians and cavalry commanders in history.
Date: 15–20 August 636
Location: Near the Yarmouk River
Result: Decisive Rashidun victory
Territorial changes: Levant annexed by Rashidun Caliphate
Belligerents::
Byzantine Empire, Ghassanid Kingdom VS Rashidun Caliphate
Strength:
Byzantine Empire: 100,000–400,000
Rashidun Caliphate: 24,000–40,000
Casualties and losses
Byzantine Empire: 70,000–120,000 killed
Rashidun Caliphate: 4,000 killed
Prelude
During the last Byzantine–Sassanid Wars in 610, Heraclius became the emperor of the Byzantine Empire, after overthrowing Phocas. Meanwhile the Sassanid Persians conquered Mesopotamia and in 611 they overran Syria and entered Anatolia, occupying Caesarea Mazaca. Heraclius, in 612, managed to expel the Persians from Anatolia, but was decisively defeated in 613 when he launched a major offensive in Syria against the Persians. Over the following decade the Persians were able to conquer Palestine and Egypt. Meanwhile Heraclius prepared for a counterattack and rebuilt his army. Nine years later in 622, Heraculis finally launched his offensive. After his overwhelming victories over the Persians and their allies in the Caucasus and Armenia, Heraclius, in 627, launched a winter offensive against the Persians in Mesopotamia winning a decisive victory at the Battle of Nineveh thus threatening the Persian capital city of Ctesiphon. Discredited by these series of disasters, Khosrau II was overthrown and 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 a majestic ceremony in 629.
Meanwhile there had been rapid political development in Arabia, where Prophet Mohammad had been preaching Islam and by 630, he had successfully united most of the Arabia under a single political authority. When the Prophet died in June 632, Abu Bakr was elected Caliph and his political successor. Troubles emerged soon after Abu Bakr's succession, when several Arab tribes openly revolted against Abu Bakr, who declared war against the rebels. In what became known as the Ridda wars (Arabic for the Wars of Apostasy, 632–33), Abu Bakr managed to unite Arabia under the central authority of the Caliph at Medina.
Map detailing the Rashidun Caliphate's invasion of the Levant.
Once the rebels had been subdued, Abu Bakr began a war of conquest, beginning with Iraq. Sending his most brilliant general, Khalid ibn al-Walid, Iraq was conquered in a series of successful campaigns against the Sassanid Persians. Abu Bakr's confidence grew, and once Khalid established his stronghold in Iraq, Abu Bakr issued a call to arms for the invasion of Syria in February 634. The Muslim invasion of Syria was a series of carefully planned and well coordinated military operations that employed strategy instead of pure strength to deal with Byzantine defensive measures. The Muslim armies, however soon proved to be too small to handle the Byzantine response, and their commanders called for reinforcements. Khalid was sent by Abu Bakr from Iraq to Syria with reinforcements and to lead the invasion. In July 634, the Byzantines were decisively defeated at Ajnadayn. Damascus fell in September 634, followed by the Battle of Fahl where the last significant garrison of Palestine was defeated and routed.
Caliph Abu Bakr died in 634. His successor, Umar, was determined to continue the Caliphate Empire's expansion deeper into Syria. Though previous campaigns led by Khalid were successful, he was replaced by Abu Ubaidah. Having secured southern Palestine, Muslim forces now advanced up the trade route where Tiberias and Baalbek fell without much struggle and the Muslims conquered Emesa early in 636. From thereon, the Muslims continued their conquest across the Levant.
Byzantine counterattack
Having seized Emesa, the Muslims were just a march away from Aleppo, a Byzantine stronghold, and Antioch, where Heraclius resided. Seriously alarmed by the series of setbacks, Heraclius prepared for a counterattack to reacquire the lost regions. In 635 Yazdegerd III, the Emperor of Persia, sought an alliance with the Byzantine Emperor. Heraclius married off his daughter (according to traditions, his grand daughter) Manyanh to Yazdegerd III, an old Roman tradition to cement the alliance. While Heraclius prepared for a major offensive in the Levant, Yazdegerd was to mount a simultaneous counterattack in Iraq, in what was meant to be a well-coordinated effort. When Heraclius launched his offensive in May 636, Yazdegerd could not coordinate with the maneuver—probably owing to the exhausted condition of his government—and what would have been a decisive plan missed the mark. Umar won a decisive victory against Heraclius at Yarmouk, and used great strategy[citation needed] to engage and entrap Yazdegerd. Three months later Yazdegerd lost his imperial army at the Battle of Qadisiyah in November 636, ending Sassanid control west of Persia.
Muslim and Byzantine Troop Movements before the battle of Yarmouk.
Byzantine preparations began in late 635 and by May 636 Heraclius had a large force concentrated at Antioch in Northern Syria. The assembled army consisted of contingents of Byzantines, Slavs, Franks, Georgians, Armenians and Christian Arabs. This force was organized into five armies, the joint leader of which was Theodore Trithourios the Sakellarios. Vahan, an Armenian and the former garrison commander of Emesa, was made the overall field commander, and had under his command a purely Armenian army. Buccinator (Qanateer), a Slavic prince, commanded the Slavs and Jabalah ibn al-Aiham, king of the Ghassanid Arabs, commanded an exclusively Christian Arab force. The remaining contingents, all European, were placed under Gregory and Dairjan. Heraclius himself supervised the operation from Antioch. Byzantine sources mention Niketas, son of the Persian general Shahrbaraz, among the commanders, but it is not certain which army he commanded.
At that time, the Rashidun army was split into four groups: one under Amr in Palestine, one under Shurahbil in Jordan, one under Yazid in the Damascus-Caesarea region and the last one under Abu Ubaidah along with Khalid at Emesa. As the Muslim forces were geographically divided, Heraclius sought to exploit this situation and planned to attack. He did not wish to engage in a single pitched battle but rather to employ central position and fight the enemy in detail by concentrating large forces against each of the Muslim corps before they could consolidate their troops. By forcing the Muslims to retreat, or by destroying Muslim forces separately, he would fulfill his strategy of recapturing lost territory. Reinforcements were sent to Caesarea under Heraclius' son Constantine III probably to tie down Yazid's forces which were besieging the town. The Byzantine imperial army moved out from Antioch and Northern Syria sometime in the middle of June 636.
The Byzantine imperial army was to operate under the following plan:
Jabalah's lightly armed Christian Arabs would march to Emesa from Aleppo via Hama and hold the main Muslim army at Emesa.
Dairjan would make a flanking movement – moving between the coast and Aleppo's road – and approach Emesa from the west, striking at the Muslims' left flank while they were being held frontally by Jabalah.
Gregory would strike the Muslims' right flank, approaching Emesa from the northeast via Mesopotamia.
Qanateer would march along the coastal route and occupy Beirut, from where he was to attack weakly defended Damascus from the west to cut off the main Muslim army at Emesa.
Vahan's corps would act as a reserve and would approach Emesa via Hama.
Muslim strategy
The Muslims discovered Heraclius' preparations at Shaizar through Roman prisoners. Alert to the possibility of being caught with separated forces that could be destroyed, Khalid called for a council of war. There he advised Abu Ubaidah to pull the troops back from Palestine and from Northern and Central Syria, and then to concentrate the entire Rashidun army in one place. Abu Ubaidah ordered the concentration of troops in the vast plain near Jabiya, as control of the area made cavalry charges possible and facilitated the arrival of reinforcements from Umar so that a strong, united force could be fielded against the Byzantine armies. The position also benefited from close proximity to the Rashidun stronghold of Najd, in case of retreat. Instructions were also issued to return the jizya (tribute) to the people who had paid it. However, once concentrated at Jabiya, the Muslims were subject to raids from pro-Byzantine Ghassanid forces. Encamping in the region was also precarious as a strong Byzantine force was garrisoned in Caeseara and could attack the Muslim rear while they were held in front by the Byzantine army. On Khalid's advice the Muslim forces retreated to Dara’ah (or Dara) and Dayr Ayyub, covering the gap between the Yarmouk Gorges and the Harra lava plains,[30] and established a line of camps in the eastern part of the plain of Yarmouk. This was a strong defensive position and these maneuvers pitted the Muslims and Byzantines into a decisive battle, one which the latter had tried to avoid. During these maneuvers, there were no engagements save for a minor skirmish between Khalid's elite light cavalry and the Byzantine advance guard.
Battle
For a good understanding of the description of the battle, it is useful to be acquainted with the divisions of opposing forces. The battle lines of the Muslims and the Byzantines were divided into four sections: the left wing, the left center, the right center and the right wing. Note that the descriptions of the Muslim and the Byzantine battle lines are exactly each other's opposite, i.e.: so the Muslim right wing faced the Byzantine left wing (see imagen[›]).
Vahan was instructed by Heraclius not to engage in battle until all avenues of diplomacy had been explored. This was probably because Yazdegerd III's forces were not yet ready for the offensive in Iraq. Accordingly, Vahan sent Gregory and then Jabalah to negotiate, though their efforts proved futile. Before the battle, on Vahan's invitation, Khalid came to negotiate peace, to a similar end. These negotiations delayed the battles for a month. On the other hand, Caliph Umar, whose forces at Qadisiyah were threatened with confronting the Sassanid armies, ordered Sa`d ibn Abi Waqqas to enter into negotiations with the Persians and send emissaries to Yazdegerd III and his commander Rostam Farrokhzād, apparently inviting them to Islam. This was most probably the delaying tactic employed by Umar on the Persian front. Meanwhile he sent reinforcements of 6,000 troops, mostly from Yemen, to Khalid. This force included 1,000 Sahaba (companions of Muhammad), among whom were 100 veterans of the Battle of Badr, the first battle in Islamic history, and included citizens of the highest rank, such as Zubayr ibn al-Awwam, Abu Sufyan, and his wife Hind bint Utbah.
Umar, apparently wanting to defeat the Byzantines first, employed the best Muslim troops against them. The continuing stream of Muslim reinforcements worried the Byzantines, who fearing that the Muslims with such reinforcements would grow powerful, decided that they had no choice but to attack. The reinforcements that were sent to the Muslims at Yarmouk arrived in small bands, giving the impression of a continuous stream of reinforcements, in order to demoralize the Byzantines and compel them to attack.[58] The same tactic would be repeated again during the Battle of Qadisiyah.
Day 1
The battle began on 15 August 636. At dawn both armies lined up for battle less than a mile apart. It is recorded in Muslim chronicles that before the battle started, George, a unit commander in the Byzantine right center, rode up to the Muslim line and converted to Islam; he would die the same day fighting on the Muslim side. The battle began as the Byzantine army sent its champions to duel with the Muslim mubarizun duel. The mubarizun were specially trained swordsmen and lancers, with the objective to slay as many enemy commanders as possible to damage their morale. At midday, after losing a number of commanders in the duels, Vahan ordered a limited attack with a third of his infantry forces to test the strength and strategy of the Muslim army and, using their overwhelming numerical and weaponry superiority, achieve a breakthrough wherever the Muslim battle line was weak. However the Byzantine assault lacked determination; many soldiers of the Imperial Army were unable to press the attack against the Muslim veterans. The fighting was generally moderate, although in some places it was especially intense. Vahan did not reinforce his forward infantry two-thirds of which was kept in reserve with one-third deployed to engage the Muslims, and at sunset both armies broke contact and returned to their respective camps.
Day 2
Phase 1: On 16 August 636, Vahan decided in a council of war to launch his attack just before dawn, to catch the Muslim force unprepared as they conducted their morning prayers. He planned to engage his two central armies with the Muslim centre in an effort to stall them while the main thrusts would be against the wings of the Muslim army, which would then either be driven away from the battlefield or pushed towards the center. To observe the battlefield, Vahan had a large pavilion built behind his right wing with an Armenian bodyguard force. He ordered the army to prepare for the surprise attack. Unbeknownst to the Byzantines, Khalid had prepared for such a contingency by placed a strong outpost line in front during the night to counter surprises, which gave the Muslims time to prepare for battle. At the center, the Byzantines did not press hard, intending to pin down the Muslim centre corps in their position and preventing them from aiding the Muslim army in other areas. Thus the center remained stable. But on the wings situation was different. Qanateer, commanding the Byzantine left flank which consisted of mainly Slavs, attacked in force, and the Muslim infantry on the right flank had to retreat. Amr, the Muslim right wing commander ordered his cavalry regiment to counterattack, which neutralized the Byzantine advance and stabilized the battle line on the right for some time, but the Byzantine numerical superiority caused them to retreat towards the Muslim base camp.
Phase 2: Khalid, aware of the situation at the wings, ordered the cavalry of the right wing to attack the northern flank of the Byzantine left wing while he with his mobile guard attacked the southern flank of the Byzantine left wing, while the Muslim right wing infantry attacked from the front. The three-pronged attack forced the Byzantine left wing to abandon the Muslim positions they had gained on, and Amr regained his lost ground and started reorganizing his corps for another round. The situation on the Muslim left wing which Yazid commanded was considerably more serious. Whilst the Muslim right wing enjoyed assistance from the mobile guard, the left wing did not and the numerical advantage the Byzantines enjoyed caused the Muslim positions to be overrun, with soldiers retreating towards base camps. Here the Byzantines had broken through the corps. The testudo formation that Gregory's army had adopted moved slowly but also had a good defense. Yazid used his cavalry regiment to counterattack but was repulsed. Despite stiff resistance, the warriors of Yazid on the left flank finally fell back to their camps and for a moment Vahan's plan appeared to be succeeding. The centre of the Muslim army was pinned down and its flanks had been pushed back. However, neither flank had broken, though their morale was severely damaged. The retreating Muslim army was met by the ferocious Arab women in the camps. Led by Hind, the Muslim women dismantled their tents and armed with tent poles charged at their husbands and fellow men singing an improvised song from the Battle of Uhud that then had been directed against the Muslims.
O you who run from a constant woman
Who has both beauty and virtue;
And leave her to the infidel,
The hated and evil infidel,
To possess, disgrace and ruin.
This boiled the blood of the retreating Muslims so much that they returned to the battlefield.
Phase 3: After managing to stabilize the position on the right flank, Khalid ordered the mobile guard cavalry to provide relief to the battered left flank. Khalid detached one regiment under Dharar ibn al-Azwar and ordered him to attack the front of the army of Dairjan (left center) in order to create a diversion and threaten the withdrawal of the Byzantine right wing from its advanced position. With the rest of the cavalry reserve he attacked Gregory's flank. Here again, under simultaneous attacks from the front and flanks, the Byzantines fell back, but more slowly because they had to maintain their formation. At sunset the central armies broke contact and withdrew to their original positions and both fronts were restored along the lines occupied in the morning. The death of Dairjan and the failure of Vahan's battle plan left the larger Imperial army relatively demoralized, whereas Khalid's successful counterattacks emboldened his troops despite their being smaller in number.
In order to check the Muslim advance and to recover lost territory, Emperor Heraclius had sent a massive expedition to the Levant in May 636. As the Byzantine army approached, the Muslims retreated from Syria and regrouped all their forces at the Yarmouk plains close to Arabia where, after being reinforced, they defeated the numerically superior Byzantine army. The battle is also considered to be one of Khalid ibn al-Walid's greatest military victories. It cemented his reputation as one of the greatest tacticians and cavalry commanders in history.
Date: 15–20 August 636
Location: Near the Yarmouk River
Result: Decisive Rashidun victory
Territorial changes: Levant annexed by Rashidun Caliphate
Belligerents::
Byzantine Empire, Ghassanid Kingdom VS Rashidun Caliphate
Strength:
Byzantine Empire: 100,000–400,000
Rashidun Caliphate: 24,000–40,000
Casualties and losses
Byzantine Empire: 70,000–120,000 killed
Rashidun Caliphate: 4,000 killed
Prelude
During the last Byzantine–Sassanid Wars in 610, Heraclius became the emperor of the Byzantine Empire, after overthrowing Phocas. Meanwhile the Sassanid Persians conquered Mesopotamia and in 611 they overran Syria and entered Anatolia, occupying Caesarea Mazaca. Heraclius, in 612, managed to expel the Persians from Anatolia, but was decisively defeated in 613 when he launched a major offensive in Syria against the Persians. Over the following decade the Persians were able to conquer Palestine and Egypt. Meanwhile Heraclius prepared for a counterattack and rebuilt his army. Nine years later in 622, Heraculis finally launched his offensive. After his overwhelming victories over the Persians and their allies in the Caucasus and Armenia, Heraclius, in 627, launched a winter offensive against the Persians in Mesopotamia winning a decisive victory at the Battle of Nineveh thus threatening the Persian capital city of Ctesiphon. Discredited by these series of disasters, Khosrau II was overthrown and 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 a majestic ceremony in 629.
Meanwhile there had been rapid political development in Arabia, where Prophet Mohammad had been preaching Islam and by 630, he had successfully united most of the Arabia under a single political authority. When the Prophet died in June 632, Abu Bakr was elected Caliph and his political successor. Troubles emerged soon after Abu Bakr's succession, when several Arab tribes openly revolted against Abu Bakr, who declared war against the rebels. In what became known as the Ridda wars (Arabic for the Wars of Apostasy, 632–33), Abu Bakr managed to unite Arabia under the central authority of the Caliph at Medina.
Map detailing the Rashidun Caliphate's invasion of the Levant.
Once the rebels had been subdued, Abu Bakr began a war of conquest, beginning with Iraq. Sending his most brilliant general, Khalid ibn al-Walid, Iraq was conquered in a series of successful campaigns against the Sassanid Persians. Abu Bakr's confidence grew, and once Khalid established his stronghold in Iraq, Abu Bakr issued a call to arms for the invasion of Syria in February 634. The Muslim invasion of Syria was a series of carefully planned and well coordinated military operations that employed strategy instead of pure strength to deal with Byzantine defensive measures. The Muslim armies, however soon proved to be too small to handle the Byzantine response, and their commanders called for reinforcements. Khalid was sent by Abu Bakr from Iraq to Syria with reinforcements and to lead the invasion. In July 634, the Byzantines were decisively defeated at Ajnadayn. Damascus fell in September 634, followed by the Battle of Fahl where the last significant garrison of Palestine was defeated and routed.
Caliph Abu Bakr died in 634. His successor, Umar, was determined to continue the Caliphate Empire's expansion deeper into Syria. Though previous campaigns led by Khalid were successful, he was replaced by Abu Ubaidah. Having secured southern Palestine, Muslim forces now advanced up the trade route where Tiberias and Baalbek fell without much struggle and the Muslims conquered Emesa early in 636. From thereon, the Muslims continued their conquest across the Levant.
Byzantine counterattack
Having seized Emesa, the Muslims were just a march away from Aleppo, a Byzantine stronghold, and Antioch, where Heraclius resided. Seriously alarmed by the series of setbacks, Heraclius prepared for a counterattack to reacquire the lost regions. In 635 Yazdegerd III, the Emperor of Persia, sought an alliance with the Byzantine Emperor. Heraclius married off his daughter (according to traditions, his grand daughter) Manyanh to Yazdegerd III, an old Roman tradition to cement the alliance. While Heraclius prepared for a major offensive in the Levant, Yazdegerd was to mount a simultaneous counterattack in Iraq, in what was meant to be a well-coordinated effort. When Heraclius launched his offensive in May 636, Yazdegerd could not coordinate with the maneuver—probably owing to the exhausted condition of his government—and what would have been a decisive plan missed the mark. Umar won a decisive victory against Heraclius at Yarmouk, and used great strategy[citation needed] to engage and entrap Yazdegerd. Three months later Yazdegerd lost his imperial army at the Battle of Qadisiyah in November 636, ending Sassanid control west of Persia.
Muslim and Byzantine Troop Movements before the battle of Yarmouk.
Byzantine preparations began in late 635 and by May 636 Heraclius had a large force concentrated at Antioch in Northern Syria. The assembled army consisted of contingents of Byzantines, Slavs, Franks, Georgians, Armenians and Christian Arabs. This force was organized into five armies, the joint leader of which was Theodore Trithourios the Sakellarios. Vahan, an Armenian and the former garrison commander of Emesa, was made the overall field commander, and had under his command a purely Armenian army. Buccinator (Qanateer), a Slavic prince, commanded the Slavs and Jabalah ibn al-Aiham, king of the Ghassanid Arabs, commanded an exclusively Christian Arab force. The remaining contingents, all European, were placed under Gregory and Dairjan. Heraclius himself supervised the operation from Antioch. Byzantine sources mention Niketas, son of the Persian general Shahrbaraz, among the commanders, but it is not certain which army he commanded.
At that time, the Rashidun army was split into four groups: one under Amr in Palestine, one under Shurahbil in Jordan, one under Yazid in the Damascus-Caesarea region and the last one under Abu Ubaidah along with Khalid at Emesa. As the Muslim forces were geographically divided, Heraclius sought to exploit this situation and planned to attack. He did not wish to engage in a single pitched battle but rather to employ central position and fight the enemy in detail by concentrating large forces against each of the Muslim corps before they could consolidate their troops. By forcing the Muslims to retreat, or by destroying Muslim forces separately, he would fulfill his strategy of recapturing lost territory. Reinforcements were sent to Caesarea under Heraclius' son Constantine III probably to tie down Yazid's forces which were besieging the town. The Byzantine imperial army moved out from Antioch and Northern Syria sometime in the middle of June 636.
The Byzantine imperial army was to operate under the following plan:
Jabalah's lightly armed Christian Arabs would march to Emesa from Aleppo via Hama and hold the main Muslim army at Emesa.
Dairjan would make a flanking movement – moving between the coast and Aleppo's road – and approach Emesa from the west, striking at the Muslims' left flank while they were being held frontally by Jabalah.
Gregory would strike the Muslims' right flank, approaching Emesa from the northeast via Mesopotamia.
Qanateer would march along the coastal route and occupy Beirut, from where he was to attack weakly defended Damascus from the west to cut off the main Muslim army at Emesa.
Vahan's corps would act as a reserve and would approach Emesa via Hama.
Muslim strategy
The Muslims discovered Heraclius' preparations at Shaizar through Roman prisoners. Alert to the possibility of being caught with separated forces that could be destroyed, Khalid called for a council of war. There he advised Abu Ubaidah to pull the troops back from Palestine and from Northern and Central Syria, and then to concentrate the entire Rashidun army in one place. Abu Ubaidah ordered the concentration of troops in the vast plain near Jabiya, as control of the area made cavalry charges possible and facilitated the arrival of reinforcements from Umar so that a strong, united force could be fielded against the Byzantine armies. The position also benefited from close proximity to the Rashidun stronghold of Najd, in case of retreat. Instructions were also issued to return the jizya (tribute) to the people who had paid it. However, once concentrated at Jabiya, the Muslims were subject to raids from pro-Byzantine Ghassanid forces. Encamping in the region was also precarious as a strong Byzantine force was garrisoned in Caeseara and could attack the Muslim rear while they were held in front by the Byzantine army. On Khalid's advice the Muslim forces retreated to Dara’ah (or Dara) and Dayr Ayyub, covering the gap between the Yarmouk Gorges and the Harra lava plains,[30] and established a line of camps in the eastern part of the plain of Yarmouk. This was a strong defensive position and these maneuvers pitted the Muslims and Byzantines into a decisive battle, one which the latter had tried to avoid. During these maneuvers, there were no engagements save for a minor skirmish between Khalid's elite light cavalry and the Byzantine advance guard.
Battle
For a good understanding of the description of the battle, it is useful to be acquainted with the divisions of opposing forces. The battle lines of the Muslims and the Byzantines were divided into four sections: the left wing, the left center, the right center and the right wing. Note that the descriptions of the Muslim and the Byzantine battle lines are exactly each other's opposite, i.e.: so the Muslim right wing faced the Byzantine left wing (see imagen[›]).
Vahan was instructed by Heraclius not to engage in battle until all avenues of diplomacy had been explored. This was probably because Yazdegerd III's forces were not yet ready for the offensive in Iraq. Accordingly, Vahan sent Gregory and then Jabalah to negotiate, though their efforts proved futile. Before the battle, on Vahan's invitation, Khalid came to negotiate peace, to a similar end. These negotiations delayed the battles for a month. On the other hand, Caliph Umar, whose forces at Qadisiyah were threatened with confronting the Sassanid armies, ordered Sa`d ibn Abi Waqqas to enter into negotiations with the Persians and send emissaries to Yazdegerd III and his commander Rostam Farrokhzād, apparently inviting them to Islam. This was most probably the delaying tactic employed by Umar on the Persian front. Meanwhile he sent reinforcements of 6,000 troops, mostly from Yemen, to Khalid. This force included 1,000 Sahaba (companions of Muhammad), among whom were 100 veterans of the Battle of Badr, the first battle in Islamic history, and included citizens of the highest rank, such as Zubayr ibn al-Awwam, Abu Sufyan, and his wife Hind bint Utbah.
Umar, apparently wanting to defeat the Byzantines first, employed the best Muslim troops against them. The continuing stream of Muslim reinforcements worried the Byzantines, who fearing that the Muslims with such reinforcements would grow powerful, decided that they had no choice but to attack. The reinforcements that were sent to the Muslims at Yarmouk arrived in small bands, giving the impression of a continuous stream of reinforcements, in order to demoralize the Byzantines and compel them to attack.[58] The same tactic would be repeated again during the Battle of Qadisiyah.
Day 1
The battle began on 15 August 636. At dawn both armies lined up for battle less than a mile apart. It is recorded in Muslim chronicles that before the battle started, George, a unit commander in the Byzantine right center, rode up to the Muslim line and converted to Islam; he would die the same day fighting on the Muslim side. The battle began as the Byzantine army sent its champions to duel with the Muslim mubarizun duel. The mubarizun were specially trained swordsmen and lancers, with the objective to slay as many enemy commanders as possible to damage their morale. At midday, after losing a number of commanders in the duels, Vahan ordered a limited attack with a third of his infantry forces to test the strength and strategy of the Muslim army and, using their overwhelming numerical and weaponry superiority, achieve a breakthrough wherever the Muslim battle line was weak. However the Byzantine assault lacked determination; many soldiers of the Imperial Army were unable to press the attack against the Muslim veterans. The fighting was generally moderate, although in some places it was especially intense. Vahan did not reinforce his forward infantry two-thirds of which was kept in reserve with one-third deployed to engage the Muslims, and at sunset both armies broke contact and returned to their respective camps.
Day 2
Phase 1: On 16 August 636, Vahan decided in a council of war to launch his attack just before dawn, to catch the Muslim force unprepared as they conducted their morning prayers. He planned to engage his two central armies with the Muslim centre in an effort to stall them while the main thrusts would be against the wings of the Muslim army, which would then either be driven away from the battlefield or pushed towards the center. To observe the battlefield, Vahan had a large pavilion built behind his right wing with an Armenian bodyguard force. He ordered the army to prepare for the surprise attack. Unbeknownst to the Byzantines, Khalid had prepared for such a contingency by placed a strong outpost line in front during the night to counter surprises, which gave the Muslims time to prepare for battle. At the center, the Byzantines did not press hard, intending to pin down the Muslim centre corps in their position and preventing them from aiding the Muslim army in other areas. Thus the center remained stable. But on the wings situation was different. Qanateer, commanding the Byzantine left flank which consisted of mainly Slavs, attacked in force, and the Muslim infantry on the right flank had to retreat. Amr, the Muslim right wing commander ordered his cavalry regiment to counterattack, which neutralized the Byzantine advance and stabilized the battle line on the right for some time, but the Byzantine numerical superiority caused them to retreat towards the Muslim base camp.
Phase 2: Khalid, aware of the situation at the wings, ordered the cavalry of the right wing to attack the northern flank of the Byzantine left wing while he with his mobile guard attacked the southern flank of the Byzantine left wing, while the Muslim right wing infantry attacked from the front. The three-pronged attack forced the Byzantine left wing to abandon the Muslim positions they had gained on, and Amr regained his lost ground and started reorganizing his corps for another round. The situation on the Muslim left wing which Yazid commanded was considerably more serious. Whilst the Muslim right wing enjoyed assistance from the mobile guard, the left wing did not and the numerical advantage the Byzantines enjoyed caused the Muslim positions to be overrun, with soldiers retreating towards base camps. Here the Byzantines had broken through the corps. The testudo formation that Gregory's army had adopted moved slowly but also had a good defense. Yazid used his cavalry regiment to counterattack but was repulsed. Despite stiff resistance, the warriors of Yazid on the left flank finally fell back to their camps and for a moment Vahan's plan appeared to be succeeding. The centre of the Muslim army was pinned down and its flanks had been pushed back. However, neither flank had broken, though their morale was severely damaged. The retreating Muslim army was met by the ferocious Arab women in the camps. Led by Hind, the Muslim women dismantled their tents and armed with tent poles charged at their husbands and fellow men singing an improvised song from the Battle of Uhud that then had been directed against the Muslims.
O you who run from a constant woman
Who has both beauty and virtue;
And leave her to the infidel,
The hated and evil infidel,
To possess, disgrace and ruin.
This boiled the blood of the retreating Muslims so much that they returned to the battlefield.
Phase 3: After managing to stabilize the position on the right flank, Khalid ordered the mobile guard cavalry to provide relief to the battered left flank. Khalid detached one regiment under Dharar ibn al-Azwar and ordered him to attack the front of the army of Dairjan (left center) in order to create a diversion and threaten the withdrawal of the Byzantine right wing from its advanced position. With the rest of the cavalry reserve he attacked Gregory's flank. Here again, under simultaneous attacks from the front and flanks, the Byzantines fell back, but more slowly because they had to maintain their formation. At sunset the central armies broke contact and withdrew to their original positions and both fronts were restored along the lines occupied in the morning. The death of Dairjan and the failure of Vahan's battle plan left the larger Imperial army relatively demoralized, whereas Khalid's successful counterattacks emboldened his troops despite their being smaller in number.