Battle of the Yarmuk

The Arab invasion of Syria began in 634 under Abu Bakr. Khalid ibn al-Walid, brought over from Iraq, led the Muslims to victory at Ajnadayn, and Damascus fell; Umar, caliph from 634, gave the supreme command to Abu Ubayda ibn al-Jarrah, and by early 636 the Arabs held Emesa (Homs). Heraclius, residing at Antioch, assembled a large army of many peoples — Armenians under Vahan, Christian Arabs under the Ghassanid king Jabala ibn al-Ayham and other contingents — under the overall command of Theodore Trithyrius, with Vahan as field commander. To avoid being defeated piecemeal, the Muslims gave up their conquests, returned the tribute they had collected to the towns they could no longer protect, and concentrated their forces on the plain east of the gorges of the Wadi al-Ruqqad, a tributary of the Yarmuk.

The fighting is usually described as lasting six days, with the decisive action on 20 August 636, although some accounts reduce it to a single day and others count three full days of fighting, not counting two days without battle. The Byzantines attacked repeatedly but could not break the Muslim line; on the last day Khalid’s massed cavalry drove the Byzantine horse from the field and fell on the infantry, which was pinned against the steep ravines, where many fell to their deaths. Theodore was killed, and Vahan probably died in the pursuit. The size of the armies is disputed: the Arab sources speak of Byzantines outnumbering the Muslims two to one, modern estimates range from 15,000 to 40,000 for each side, and some historians argue for a much larger Byzantine army.

The Yarmuk decided the fate of Syria. Damascus was reoccupied, Jerusalem capitulated to Caliph Umar in 637 or 638 after a siege — the patriarch Sophronius negotiated the surrender — and the other cities followed. Heraclius withdrew from Antioch to Constantinople; later tradition put into his mouth a lament of farewell to Syria. The defeat left Egypt exposed, and in 639 Amr ibn al-As, who had fought at the Yarmuk, invaded it.