Siege of Constantinople (717–718) in the context of "Walls of Constantinople"

The Arab–Byzantine wars or Muslim–Byzantine wars were a series of wars from the 7th to 11th centuries between multiple Arab dynasties and the Byzantine Empire. The Muslim Arab Caliphates conquered large parts of the Christian Byzantine empire and unsuccessfully attacked the Byzantine capital of Constantinople. The frontier between the warring states remained almost static for three centuries of frequent warfare, before the Byzantines were able to recapture some of the lost territory.

The conflicts began during the 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 southern provinces. Syria was captured in 639 and Egypt was conquered in 642. The Exarchate of Africa was gradually captured between 647 and 670. From the 650s onwards, Arab navies entered the Mediterranean Sea, which became a major battleground. Both sides launched 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 failed to seize the heavily fortified Byzantine capital.

Maslama ibn Abd al-Malik (fl. 705 – 24 December 738) was an Umayyad prince and one of the most prominent Arab generals of the early decades of the 8th century, leading several campaigns against the Byzantine Empire and the Khazar Khaganate. He achieved great fame especially for leading the last Arab siege of the Byzantine capital Constantinople.

He launched his military career leading the annual summer raids against the Byzantines in Anatolia. By 709, he was governor over Qinnasrin (northern Syria), the Jazira (Upper Mesopotamia), Armenia, and Adharbayjan, giving him control over the Caliphate's northern frontier. From this position, he launched the first Arab expeditions against the Khazars across the Caucasus. Maslama's brother, Caliph Sulayman, appointed him to lead the campaign to capture Constantinople in 715, but it ended in disaster for the Arabs and he was ordered to withdraw by Sulayman's successor, Umar II, in 718.

Sulayman ibn Abd al-Malik ibn Marwan (c. 675 – 24 September 717) was the seventh Umayyad caliph, ruling from 715 until his death. He was the son of Caliph Abd al-Malik and Wallada bint al-Abbas. He began his career as governor of Palestine, while his father Abd al-Malik (r. 685–705) and brother al-Walid I (r. 705–715) reigned as caliphs. There, the theologian Raja ibn Haywa mentored him, and he forged close ties with Yazid ibn al-Muhallab, a major opponent of al-Hajjaj ibn Yusuf, al-Walid's powerful viceroy of Iraq and the eastern Caliphate. Sulayman resented al-Hajjaj's influence over his brother. As governor, Sulayman founded the city of Ramla and built the White Mosque in it. The new city superseded Lydda as the district capital of Palestine. Lydda was at least partly destroyed and its inhabitants may have been forcibly relocated to Ramla, which developed into an economic hub, became home to many Muslim scholars, and remained the commercial and administrative center of Palestine until the 11th century.

After acceding as caliph, Sulayman dismissed his predecessor's governors and generals. Many had been handpicked by al-Hajjaj and had led the war efforts which brought the Caliphate to its greatest territorial extent. Among them were the conqueror of Transoxiana (Central Asia), Qutayba ibn Muslim, who was killed by his own troops in an abortive revolt in anticipation of his dismissal, and the conqueror of Sind (the western Indian subcontinent), Muhammad ibn al-Qasim, who was executed. In the west, Sulayman deposed Musa ibn Nusayr, the conqueror of the Iberian Peninsula (al-Andalus) and governor of Ifriqiya (central North Africa), and had his son Abd al-Aziz, governor of al-Andalus, assassinated. Although he continued his predecessors' militarist policies, expansion largely stopped under Sulayman, partly due to effective resistance along the Central Asian frontiers and the collapse of Arab military leadership and organization there after Qutayba's death. Sulayman's appointee over the eastern Caliphate, his confidant Yazid, invaded the southern Caspian coast in 716, but withdrew and settled for a tributary arrangement after being defeated by the local Iranian rulers. Sulayman intensified the war with the Byzantine Empire, the primary focus of his war efforts, culminating in the 717–718 siege of Constantinople, which ended in a disastrous Arab defeat.

Tervel (Bulgarian: Тервел), also called Tarvel, Terval, or Terbelis in Byzantine sources, was the ruler of Bulgaria during the First Bulgarian Empire at the beginning of the 8th century. In 705 Emperor Justinian II named him caesar, the first foreigner to receive this title. He was raised a pagan like his grandfather Khan Kubrat, but was later possibly baptised by the Byzantine clergy. Tervel played an important role in defeating the Arabs during the siege of Constantinople in 717–718. The Nominalia of the Bulgarian khans states that Tervel belonged to the Dulo clan and reigned for 21 years. The testimony of the source and some later traditions allow identifying Tervel as the son of Asparukh.