Battle of Yarmouk (636): Arab Victory over Byzantine Syria

The Battle of Yarmouk, fought in August 636 in the valley of the Yarmouk River east of the Sea of Galilee, was one of the most decisive battles of the early Middle Ages. Arab Muslim armies of the Rashidun caliphate, with Khalid ibn al-Walid as their leading field commander, destroyed the main Byzantine army in the region. The result settled the fate of Syria and Palestine, which passed from Roman to Muslim rule after nearly 700 years.

Background

In 628 the Byzantine (Eastern Roman) emperor Heraclius ended a gruelling war with Sasanian Persia in victory, recovering Syria, Palestine and Egypt. The Byzantine-Sasanian War of 602–628 had, however, drained both empires of men and money and disrupted Roman administration across the Near East.

At the same time a new power was forming in Arabia. After the death of the Prophet Muhammad in 632, the first caliph, Abu Bakr, reunited the Arabian tribes and sent armies north. The Rashidun caliphate under Abu Bakr and then Umar ibn al-Khattab (from 634) struck at both Byzantine Syria and Sasanian Iraq.

In Syria the Muslim forces won at Ajnadayn in 634 and at Fahl (Pella) in early 635, and Damascus surrendered in 635 after a siege. Khalid ibn al-Walid, who had marched across the desert from Iraq, became the most prominent Muslim commander, while Abu Ubayda ibn al-Jarrah held overall command after Umar’s accession.

The armies

Heraclius, based at Antioch and Emesa (Homs), assembled a large army in 636 to drive the Arabs out. It included Armenian troops, Greek-speaking regulars, Christian Arab allies of the Ghassanid confederation under Jabala ibn al-Ayham, and other contingents. The senior commander was the Armenian general Vahan, with the treasurer (sakellarios) Theodore Trithyrius also holding a major command.

Faced with this army, the Muslim commanders abandoned Emesa and Damascus and concentrated their forces south of the Yarmouk, near al-Jabiya and the plateau above the river. The position gave them open ground for their cavalry and access to the desert behind them.

Numbers are highly uncertain. Arabic chronicles give the Byzantines 100,000 to 200,000 men and the Muslims around 24,000 to 40,000. Modern historians such as Walter Kaegi consider the medieval figures far too high and suggest that each side probably fielded somewhere between 15,000 and 40,000 men, with the Byzantines likely the larger force.

What happened

The armies faced each other for weeks, perhaps longer, while negotiations and skirmishes took place. The main battle, according to Arabic tradition, lasted six days in August 636. Details of the individual days come mostly from later Arabic writers such as al-Tabari and al-Baladhuri, and modern reconstructions differ.

In the early days the Byzantines attacked the Muslim lines repeatedly and at times pushed them back to their camp. Arabic sources stress the role of Muslim women in the camp, who are said to have urged retreating men back into the fight. Khalid kept a mobile cavalry reserve that he used to counterattack where the Byzantine assaults broke through.

On the decisive days the Muslim cavalry drove the Byzantine horsemen off the field and separated them from their infantry. A Muslim detachment seized the crossing over the deep ravine of the Wadi al-Ruqqad, cutting the Byzantine line of retreat westward. Trapped between the ravines and the Muslim army, the Byzantine infantry was overwhelmed. Many soldiers died in the fighting or fell into the gorges.

Some traditions say a dust storm blew into the faces of the Byzantine troops on the last day. The Byzantine chronicler Theophanes, writing much later, reports that discontented troops proclaimed Vahan emperor during the campaign, a sign of deep divisions in the Byzantine camp. Neither story can be confirmed in detail.

Why the Byzantines lost

Historians have offered several explanations for the scale of the Byzantine defeat. The first is command. Byzantine authority was divided between several generals of different backgrounds, and the sources hint at rivalry between Vahan and Theodore Trithyrius. Some Christian Arab allies are said to have wavered or changed sides, although the details are disputed.

The second is the state of the empire. The long war with Persia had ended only eight years earlier. Imperial finances were strained, pay was often late, and Syria had been under Persian occupation for more than a decade before 628, so Roman administration and local loyalties had not been fully rebuilt.

The third is the nature of the Muslim army. It was smaller but highly motivated, united by a new faith and by the prospect of booty, and led by commanders who had fought together for years. Its cavalry was fast and well led, and its leaders chose ground that suited them. By waiting near the desert edge the Muslims kept a secure line of retreat, while the Byzantines ended up fighting with deep ravines at their backs.

Finally, the long standoff before the battle seems to have worn down Byzantine morale and supplies. When the Byzantine army finally broke, it had nowhere safe to go, which turned a defeat into a disaster.

Key people

• Khalid ibn al-Walid (died 642): a member of the Quraysh tribe of Mecca who had once fought against Muhammad, then became the most celebrated general of the early conquests. He is credited with the tactical handling of the battle.
• Abu Ubayda ibn al-Jarrah (died 639): an early companion of Muhammad and overall commander of the Muslim forces in Syria, appointed by Umar.
• Vahan: an Armenian commander who led the Byzantine army; his fate after the battle is unclear.
• Heraclius (reigned 610–641): the emperor who organised the campaign from northern Syria but did not fight at Yarmouk himself.
• Umar ibn al-Khattab (caliph 634–644): directed the conquests from Medina and sent reinforcements to Syria.

Consequences

Yarmouk destroyed the only large Byzantine field army in the Levant. Damascus was retaken by the Muslims soon after, and Emesa, Aleppo and Antioch fell within about two years. Jerusalem surrendered to the caliph Umar in person, probably in 637 or 638, and the coastal stronghold of Caesarea held out until around 640–641.

Heraclius withdrew from Syria to Anatolia. Later Arabic writers attribute to him a famous farewell to the province, but the exact wording is literary rather than documented. From then on the Taurus Mountains became the frontier between Byzantium and the caliphate.

The victory also freed Muslim forces for other fronts. In the same period the Arabs defeated the Sasanians at the Battle of al-Qadisiyyah, and from late 639 Amr ibn al-As led the Muslim conquest of Egypt, which again exploited Byzantine weakness after Yarmouk.

Legacy

For Byzantium, the loss of Syria, Palestine and soon Egypt transformed the empire into a smaller, mainly Greek-speaking state centred on Anatolia and Constantinople. Historians often see this as the moment the late Roman Empire became the medieval Byzantine Empire.

For the new Islamic state, the conquest of Syria gave it a wealthy, urban, largely Christian province that soon became its political centre. Damascus later served as the capital of the Umayyad caliphs from 661 to 750. The battle remains a celebrated event in Arab and Muslim historical memory, and Khalid ibn al-Walid is still widely honoured as a military hero.

Timeline

• 634, July: Muslim victory over a Byzantine army at Ajnadayn in Palestine.
• 635, January: Muslim victory at Fahl (Pella) in the Jordan valley.
• 635: Damascus surrenders to the Muslim forces.
• 636, spring–summer: Heraclius’s new army advances; the Muslims withdraw from Emesa and Damascus.
• 636, August: the Battle of Yarmouk ends in a decisive Muslim victory.
• 637 or 638: Jerusalem surrenders to the caliph Umar.
• c. 640–641: fall of Caesarea, the last major Byzantine stronghold in Palestine.

Why it matters

Yarmouk decided who would rule the eastern Mediterranean lands for centuries. It ended Roman rule in Syria and Palestine, set the Byzantine-Islamic frontier in the Taurus Mountains and gave the young caliphate the resources and base from which it expanded across three continents.