2 – Battle of Akroinon (739 or 740)
Since the beginning of the early Muslim conquests in 622, Byzantium was one of the major enemies of the Arabs. The Byzantines suffered a succession of crucial defeats such as the catastrophe at Yarmouk in 636 and the loss at Heliopolis in 640. The Byzantines repelled attempted Arab sieges of Constantinople but another heavy defeat, this time at the Battle of Sebastopolis in 692, placed them on the defensive. That battle had marked the end of over a decade of peace between the two warring factions.
The Umayyad Caliphate failed to capture Constantinople after a lengthy siege in 717-718 and turned their attention away from the Byzantine capital for a couple of years. However, they renewed their offensive in 720 with annual incursions into enemy territory designed to plunder and destroy the Byzantine countryside. The goal was to wear the enemy down, and the raids became more aggressive during the 730s.
After more successful raids in the late 730s, the Arab Caliph, Hisham ibn Abd al-Malik, launched the largest invasion of his entire reign in 739/740. The 90,000 strong invading force was led by the Caliph’s son, Sulayman, and he divided it into three sections. 10,000 raided the western coastlands, 60,000 went to Cappadocia under Sulayman’s command, and the other 20,000 marched towards Akroinon.
It was here that the Byzantine Emperor, Leo III the Isaurian, and his son (who later became Constantine V) encountered the invaders. Details of the battle are sketchy, but it appears as if Leo and his son outmaneuvered the enemy and won a crushing victory. The two Arab commanders, Abd Allah and Malik, were killed in action and an estimated 13,200 Arabs fell at Akroinon.
Although the rest of the Arab forces succeeded in one goal, to cause devastation to the enemy countryside, they failed to take any major Byzantine forts or towns. The Battle of Akroinon was a turning point in the Byzantine-Arab Wars because it forced the Arabs to reduce the pressure on their enemies. It also weakened the Umayyad Caliphate, and within a decade, it had been overthrown by the Abbasids. The Arabs were pushed out of Asia Minor and did not launch any major incursions for the next three decades.