6 – Constantine V – 775
The reign of Leo III ‘the Isaurian’ was the beginning of almost 60 years of good rule and marked the start of a Byzantine recovery. When he died in 741, he was succeeded by his son, Constantine V, who was almost as good a ruler as his father. He faced opposition immediately from his brother-in-law, Artabasdos, but defeated his enemy within 18 months.
Although he is best known for his iconoclastic policies, Constantine was generally an excellent ruler who had a good grasp of how to manage the resources of the state. He reorganized the ‘theme’ system and created tagmata, new army field divisions. The purpose of the new system was to reduce the possibility of conspiracies and improve the Empire’s ability to defend itself.
While he didn’t make any concrete gains, Constantine’s reign is noteworthy for the fact that he went on the offensive against the Arabs. For the previous century, the Byzantines were intent to cling on to their possessions, with limited success. He was also successful in the Balkans with significant victories over the Bulgarians near the Anastasian Wall and at Marcellae. Although the Bulgarians inflicted heavy casualties on the Byzantines at the Battle of the Rishki Pass in 759, Constantine gained revenge at the Battle of Anchialus in 763.
He died in 775 while planning another campaign against the Bulgarians. Constantine’s son, Leo IV, became the new emperor but only reigned for five years. By the end of the eighth century, the Byzantines suffered significant losses against the Bulgarians and also against the Arabs under Caliph Harun al-Rashid. The Empire was only able to recover on the Eastern front due to an outbreak of civil war amongst the Arabs in 842.