718 CE

Siege of Constantinople: A Bulgar relief force attacks the siege lines at Constantinople, on the west side of the Bosporus. Contemporary chroniclers report that at least 22,000–32,000 Arabs are killed during the Bulgarian attacks. Caliph Umar II is forced to lift the siege after 13 months; the Muslim army attempts to withdraw back through Anatolia, while the rest escapes by sea in the remaining vessels. The Arab fleet suffers further casualties to storms, and an eruption of the volcano of Thera. According to Arab sources 150,000 Muslims perish during the campaign. Summer – Battle of Covadonga: Pelagius (Don Pelayo) is proclaimed king (caudillo), and defeats the Umayyad forces under Munuza, provincial governor of Asturias, at Picos de Europa (near Covadonga). This marks the beginning of the Reconquista, the Christian reconquest of the Iberian Peninsula. He founds the Kingdom of Asturias, and establishes a military base at Cangas de Onís (northwest of Spain) (or 722). Spring – A Muslim supply fleet of 760 ships under Sufyan arrives from Egypt and North Africa, concealing itself along the Asiatic shore. The Byzantines learn of the fleet's location from defecting Christian Egyptian sailors. Emperor Leo III sends the Byzantine navy again; his Greek fire ships destroy the enemy vessels in the Sea of Marmara and seize their supplies on shore, denying the sieging army vital provisions. On land the Byzantine troops ambush an advancing Arab army, and destroy it in the hills around Sophon, south of Nicomedia (modern Turkey). The Arab besiegers are still suffering from hunger and pestilence.

In the 710s, the 8th century.