The Arab–Byzantine wars or Muslim–Byzantine wars were a series of wars from the 7th to 11th centuries between the successive Islamic caliphates and the Byzantine Empire. Following the Byzantine defeat at the Battle of the Yarmuk, Muslim armies conquered most Byzantine territory in the Levant, Egypt and North Africa within decades. Arab expansion subsequently slowed to a more gradual rate, following two failed sieges of the Byzantine capital of Constantinople in the late 7th and early 8th centuries. By the mid-9th century, the Byzantines had partially recovered and proceeded to recapture some of their lost territory in Anatolia in the following decades.
The conflict began during early Muslim conquests under the expansionist Rashidun Caliphate, part of the initial spread of Islam. In the 630s, Rashidun forces from Arabia attacked and quickly overran Byzantium's Levantine and African provinces. Syria was captured in 639 and Egypt was conquered in 642. The Exarchate of Africa was gradually seized between 647 and 670. From the 650s onward, Arab naval forces began entering the Mediterranean Sea, which subsequently became a major battleground, with both sides launching raids and counterraids against islands and coastal settlements. The Rashidun were succeeded by the Umayyad Caliphate in 661, who over the next fifty years captured Byzantine Cyrenaica and launched repeated raids into Byzantine Asia Minor. Umayyad forces twice placed Constantinople under siege, in 674 to 678 and 717 to 718, but ultimately failed to seize the heavily fortified Byzantine imperial capital.
Following the failed second siege, the border stabilized at the Taurus Mountains in Asia Minor. The Umayyads, and later the Byzantines, launched frequent attacks across this frontier, which was heavily fortified by both sides. As a result, the surrounding region became depopulated due to constant warfare. During the initial period of conflict in the 7th and early 8th centuries, the Byzantines were usually on the defensive, avoiding open battles and preferring to retreat to fortified strongholds. After the mid-8th century Byzantine forces began to launch their own counter-offensives across the frontier at the Taurus Mountains, and further abroad by sea.
In 750 the Umayyads were overthrown by the Abbasid Caliphate, who were less expansionist than their predecessors. Conflict persisted, however, with near-annual clashes until the mid-10th century. Abbasid vassals conquered Crete in 827 and gradually took Sicily from 831 to 878, with Arab naval raids peaking in the 9th and early 10th centuries, including attacks along the coasts of Italy and Dalmatia.
Unrest in the Abbasid Empire beginning in 861 disrupted further expansion, and the Byzantines underwent a military resurgence under the Macedonian dynasty. From c. 920 to 976, the Byzantines pushed Arab forces back in Anatolia, recovering lost territories in northern Syria and Armenia. Crete was reconquered in 961. By the end of the 10th century the Fatimid Caliphate had replaced the Abbasids as the major Arab power in the Levant, and halted further Byzantine advances.
Background
The prolonged and escalating Byzantine–Sasanian wars of the 6th and 7th centuries and the recurring outbreaks of bubonic plague (Plague of Justinian) left both empires exhausted and vulnerable in the face of the sudden emergence and expansion of the Arabs. The last of the wars between the Roman and Persian empires ended with victory for the Byzantines: Emperor Heraclius regained all lost territories, and restored the True Cross to Jerusalem in 629.
Nevertheless, neither empire was given any chance to recover, as within a few years they found themselves in conflict with the Arabs (newly united by Islam), which, according to Howard-Johnston, "can only be likened to a human tsunami". According to George Liska, the "unnecessarily prolonged Byzantine–Persian conflict opened the way for Islam".
In the late 620s, the Islamic Prophet Muhammad had already managed to unify much of Arabia under Muslim rule via conquest as well as making alliances with neighboring tribes, and it was under his leadership that the first Muslim–Byzantine skirmishes took place. Just a few months after Emperor Heraclius and the Persian general Shahrbaraz agreed on terms for the withdrawal of Persian troops from occupied Byzantine eastern provinces in 629, Arab and Byzantine troops confronted each other at the Battle of Mu'tah in response to the murder of Muhammad's ambassador at the hands of the Ghassanids, a Byzantine vassal kingdom. Muhammad died in 632 and was succeeded by Abu Bakr, the first Caliph with undisputed control of the entire Arabian Peninsula after the successful Ridda Wars, which resulted in the consolidation of a powerful Muslim state throughout the peninsula.
History
Arab conquests, 629–718
According to Muslim biographies, Muhammad, having received intelligence that Byzantine forces were concentrating in northern Arabia with intentions of invading Arabia, led a Muslim army north to Tabuk in present-day northwestern Saudi Arabia, with the intention of pre-emptively engaging the Byzantine army, however, the Byzantine army had retreated beforehand. Though it was not a battle in the typical sense, nevertheless the event represented the first Arab encounter against the Byzantines. It did not, however, lead immediately to a military confrontation.
There is no contemporary Byzantine account of the Tabuk expedition, and many of the details come from much later Muslim sources. It has been argued that there is in one Byzantine source possibly referencing the Battle of Mu´tah traditionally dated 629, but this is not certain. The first engagements may have started as conflicts with the Arab client states of the Byzantine and Sassanid empires: the Ghassanids and the Lakhmids of Al-Hirah. In any case, Muslim Arabs after 634 certainly pursued a full-blown offensive against both empires, resulting in the conquest of Syria, Egypt and Persia for Islam. The most successful Arab generals were Khalid ibn al-Walid and 'Amr ibn al-'As.
Arab conquest of Roman Syria: 634–638
In the Levant, the invading Rashidun army were engaged by a Byzantine army composed of imperial troops as well as local levies. According to Islamic historians, Monophysites and Jews throughout Syria welcomed the Arabs as liberators, as they were discontented with the rule of the Byzantines.
The Roman Emperor Heraclius had fallen ill and was unable to personally lead his armies to resist the Arab conquests of Syria and Roman Palestine in 634. In a battle fought near Ajnadayn in the summer of 634, the Rashidun army achieved a decisive victory. After their victory at the Fahl, Muslim forces conquered Damascus in 634 under the command of Khalid ibn al-Walid. The Byzantine response involved the collection and dispatch of the maximum number of available troops under major commanders, including Theodore Trithyrius and the Armenian general Vahan, to eject the Muslims from their newly won territories.
At the Battle of the Yarmuk in 636, however, the Muslims, having studied the ground in detail, lured the Byzantines into pitched battle, which the Byzantines usually avoided, and into a series of costly assaults, before turning the deep valleys and cliffs into a catastrophic death-trap. Heraclius' farewell exclamation (according to the 9th-century historian Al-Baladhuri) while departing Antioch for Constantinople, is expressive of his disappointment: "Peace unto thee, O Syria, and what an excellent country this is for the enemy!" The impact of Syria's loss on the Byzantines is illustrated by Joannes Zonaras' words: "[...] since then [after the fall of Syria] the race of the Ishmaelites did not cease from invading and plundering the entire territory of the Romans".
In April 637, the Arabs, after a long siege, captured Jerusalem, which was surrendered by Patriarch Sophronius. In the summer of 637, the Muslims conquered Gaza, and, during the same period, the Byzantine authorities in Egypt and Mesopotamia purchased an expensive truce, which lasted three years for Egypt and one year for Mesopotamia. Antioch fell to the Muslim armies in late 637, and by then the Muslims occupied the whole of northern Syria, except for upper Mesopotamia, which they granted a one-year truce.
At the expiration of this truce in 638–639, the Arabs overran Byzantine Mesopotamia and Byzantine Armenia, and terminated the conquest of Palestine by storming Caesarea Maritima and effecting their final capture of Ascalon. In December 639, the Muslims departed from Palestine to invade Egypt in early 640.
Arab conquests of North Africa: 639–698
By the time Heraclius died, much of Egypt had been lost, and by 637–638 the whole of Syria was in the hands of the armies of Islam. With 3,500–4,000 troops under his command, 'Amr ibn al-A'as first crossed into Egypt from Palestine at the end of 639 or the beginning of 640. He was progressively joined by further reinforcements, notably 12,000 soldiers by Zubayr ibn al-Awwam. 'Amr first besieged and conquered Babylon Fortress, and then attacked Alexandria. The Byzantines, divided and shocked by the sudden loss of so much territory, agreed to give up the city by September 642. The fall of Alexandria extinguished Byzantine rule in Egypt, and allowed the Muslims to continue their military expansion into North Africa; between 643 and 644 'Amr completed the conquest of Cyrenaica. Uthman succeeded Caliph Umar after his death.
According to Arab historians, the local Christian Copts welcomed the Arabs just as the Monophysites did in Jerusalem. The loss of this lucrative province deprived the Byzantines of their valuable wheat supply, thereby causing food shortages throughout the Byzantine Empire and weakening its armies in the following decades.
The Byzantine navy briefly won back Alexandria in 645, but lost it again in 646 shortly after the Battle of Nikiou. The Islamic forces raided Sicily in 652, while Cyprus and Crete were captured in 653. However, Crete reverted to Eastern Roman rule until the 820s.
The people of Homs replied [to the Muslims], "We like your rule and justice far better than the state of oppression and tyranny in which we were. The army of Heraclius we shall indeed, with your 'amil's' help, repulse from the city." The Jews rose and said, "We swear by the Torah, no governor of Heraclius shall enter the city of Homs unless we are first vanquished and exhausted!" [...] The inhabitants of the other cities—Christian and Jews—that had capitulated to the Muslims, did the same [...] When by Allah's help the "unbelievers" were defeated and the Muslims won, they opened the gates of their cities, went out with the singers and music players who began to play, and paid the kharaj."
In 647, a Rashidun army led by Abd Allah ibn Sa'd invaded the Byzantine Exarchate of Africa. Tripolitania was conquered, followed by Sufetula, 150 miles (240 km) south of Carthage, and the governor and self-proclaimed Emperor of Africa Gregory was killed. Abdallah's booty-laden force returned to Egypt in 648 after Gregory's successor, Gennadius, promised them an annual tribute of some 300,000 nomismata.
Following the First Muslim Civil War, the Umayyads came to power in the Arab Empire under Mu'awiya I. Under the Umayyads the conquest of the remaining Byzantine and northern Berber territories in North Africa was completed, enabling the Arabs to invade Visigothic Spain through the Strait of Gibraltar, under the command of the Berber general Tariq ibn Ziyad. But this happened only after they developed a naval power of their own, and they conquered and destroyed the Byzantine stronghold of Carthage between 695 and 698. The loss of Africa meant that soon, Byzantine control of the Western Mediterranean was challenged by a new and expanding Arab fleet, operating from Tunisia.
Mu'awiya began consolidating the Arab territory from the Aral Sea to the western border of Egypt. He put a governor in place in Egypt at al-Fustat, and launched raids into Anatolia in 663. Then from 665 to 689 a new North African campaign was launched to protect Egypt "from flank attack by Byzantine Cyrene". An Arab army of 40,000 took Barca, defeating 30,000 Byzantines.
A vanguard of 10,000 Arabs under Uqba ibn Nafi followed from Damascus. In 670, Kairouan (modern Tunisia) was established as a base for further invasions; Kairouan would become the capital of the Islamic province of Ifriqiya, and one of the main Arabo-Islamic religious centers in the Middle Ages. Uqba "plunged into the heart of the country, traversed the wilderness in which his successors erected the splendid capitals of Fes and Morocco, and at length penetrated to the verge of the Atlantic and the great desert".
In his conquest of the Maghreb, Uqba ibn Nafi took the coastal cities of Bejaia and Tangier, overwhelming what had once been the Roman province of Mauretania where he was finally halted. As the historian Luis Garcia de Valdeavellano explains:
In their struggle against the Byzantines and the Berbers, the Arab chieftains had greatly extended their African dominions, and as early as the year 682 Uqba had reached the shores of the Atlantic, but he was unable to occupy Tangier, for he was forced to turn back toward the Atlas Mountains by a man who became known to history and legend as Count Julian.
— Luis Garcia de Valdeavellano
Arab attacks on Anatolia and sieges of Constantinople
As the first tide of the Muslim conquests in the Near East ebbed off, and a semi-permanent border between the two powers was established, a wide zone, unclaimed by either Byzantines or Arabs and virtually deserted (known in Arabic as al-Ḍawāḥī, "the outer lands" and in Greek as τὰ ἄκρα, ta akra, "the extremities") emerged in Cilicia, along the southern approaches of the Taurus and Anti-Taurus mountain ranges, leaving Syria in Muslim and the Anatolian plateau in Byzantine hands. Both Emperor Heraclius and the Caliph 'Umar (r. 634–644) pursued a strategy of destruction within this zone, trying to transform it into an effective barrier between the two realms.
Nevertheless, the Umayyads still considered the complete subjugation of Byzantium as their ultimate objective. Their thinking was dominated by Islamic teaching, which placed the infidel Byzantines in the Dār al-Ḥarb, the "House of War", which, in the words of Islamic scholar Hugh N. Kennedy, "the Muslims should attack whenever possible; rather than peace interrupted by occasional conflict, the normal pattern was seen to be conflict interrupted by occasional, temporary truce (hudna). True peace (ṣulḥ) could only come when the enemy accepted Islam or tributary status."