Battles & Wars › Medieval wars › Early Muslim conquests
Battle of the Yarmouk
August 636· Battle· Middle East & Africa
Well documentedSolid records, physical evidence or scientific consensus.
A Muslim Arab army under Khalid ibn al-Walid routed the Byzantine army near the Yarmouk River, opening Syria to conquest.
See it on the Battles & Wars map →What happened
Emperor Heraclius gathered a large, many-nationed army to retake Syria from the Arab forces that had recently entered it. The two sides met by the Yarmouk, a tributary of the Jordan, south of the Golan Heights. After about six days of fighting in August 636, Arab cavalry under Khalid ibn al-Walid cut off the Byzantine retreat and trapped much of the army against steep ravines. Byzantine losses were heavy. Modern estimates of army sizes vary widely, from about 15,000 to over 50,000 a side.
Why it matters
Byzantium lost Syria and Palestine for good, including Jerusalem, which surrendered about 637–638. The road to Egypt and wider conquest lay open.
How we know
Arab historians such as al-Baladhuri and al-Tabari, writing in the 800s and 900s, and brief Byzantine notes by Theophanes. The outcome is certain; the details are less reliable.
Still debated
The exact dates, army sizes and course of the six days are uncertain, because the main accounts were written about two centuries later.
Connections (2)
▸Battle of the Yarmouk took Syria from the eastern half of Roman EmpireWell documented
The connection
Yarmouk destroyed the army Emperor Heraclius had gathered to hold Syria. He withdrew to Anatolia, and Damascus, Jerusalem and the coastal cities surrendered within a few years. The eastern Roman (Byzantine) Empire lost its richest provinces, then Egypt by 642, and shrank to a Greek-speaking state centered on Anatolia and Constantinople.
When and how
Yarmouk River valley, August 636; the Byzantine field army against the forces of the early caliphate; Jerusalem surrendered about 637–638.
How we know
Byzantine and Arab sources agree on the defeat and Heraclius's withdrawal; later coins, papyri and administrative records show Syria under caliphal rule.
Debates and open questions
Whether Byzantine rule in Syria was already fragile, because of religious disputes and exhaustion from the long war with Persia, is debated.
▸Battle of the Yarmouk was a decisive early victory of Early Muslim conquestsWell documented
The connection
Yarmouk was the young caliphate's first great test against a superpower. Victory gave the Muslims Syria and Palestine, a base with wealth, cities and roads. Together with victory over Persia at Qadisiyyah around the same time, it proved the conquests were more than raids and opened the way to Egypt.
When and how
Near the Yarmouk River, south of the Golan Heights, August 636; Khalid ibn al-Walid and Abu Ubayda commanding.
How we know
Arabic and Byzantine chronicles agree on the outcome, and the quick surrender of Syrian cities afterward is well attested.
Debates and open questions
Qadisiyyah's date is uncertain (636–638), so which victory came first and which mattered more is debated.