Twenty Years' Anarchy - Byzantine Empire

The Twenty Years' Anarchy is a term used for the period of acute internal instability in the Byzantine Empire, marked by the rapid succession of several emperors to the throne between the first deposition of Justinian II in 695 and the ascent of Leo III the Isaurian to the throne in 717, marking the beginning of the Isaurian dynasty.

Hagia Sophia, originally constructed as a church between 532 and 537

Justinian II, was the Byzantine Emperor, reigning from 685 to 695 and again from 705 to 711. Justinian II was an ambitious and passionate ruler who was keen to restore the Roman Empire to its former glories, but he responded poorly to any opposition to his will and lacked the finesse of his father, Constantine IV.

Coin of Justinian II

Justinian II set in motion a chain of events by embarking on a despotic and increasingly violent course. His policies met with considerable opposition, eventually provoking a rebellion led by Leontios (695–698) in 695, which deposed and exiled him, precipitating a prolonged period of instability and anarchy, with seven emperors in twenty-two years.

Leontios

Leontios was Byzantine emperor from 695 to 698. He led forces against the Umayyads during the early years of Justinian's reign, securing victory and forcing the Umayyad caliph, Abd al-Malik ibn Marwan, to sue for peace. He led a rebellion against Justinian, and seized power, becoming emperor in 695 CE.  He led a march on the guards barracks, freeing those who were imprisoned by Justinian for opposing him. His force was joined by a host of Blues supporters, and then marched to the Hagia Sophia.

Mural in Hagia Sophia, Istanbul

Leontios proved equally unpopular and was in turn overthrown by Tiberios III (698–705). As emperor, he made the tactical decision to ignore Africa, where Carthage was now definitively lost. Instead, he appointed his brother Heraclius as monostrategos of the East, who firstly strengthened the land and sea defences of Anatolia before proceeding to attack the Umayyad Caliphate under Abd al-Malik, winning minor victories while raiding into northern Syria in 700 and 701.

Ven, Turkey(Former part of Anatolia)

Tiberios managed to bolster the eastern frontier and reinforced the defenses of Constantinople, but meanwhile Justinian was conspiring to make a comeback and after forming an alliance with the Bulgars succeeded in taking Constantinople and executing Tiberios. His second reign was marked by unsuccessful warfare against Bulgaria and the Caliphate, and by cruel suppression of opposition at home.

Restored walls of Constantinople

Justinian II then continued to reign for a further six years (705–711). In 708 he turned on Bulgarian Khan Tervel, whom he had earlier crowned Caesar, and invaded Bulgaria. The Emperor was defeated, blockaded in Anchialus, and forced to retreat. Peace between Bulgaria and Byzantium was quickly restored. This defeat was followed by Arab victories in Asia Minor, where the cities of Cilicia fell into the hands of the enemy, who penetrated into Cappadocia in 709–711.

Landscape view of Cappadocia

His treatment of Tiberios and his supporters had been brutal and he continued to rule in a manner that was despotic and cruel. He lost the ground regained by Tiberios in the east, and imposed his views on the Pope John VII. However, before long he faced a rebellion led by Philippikos Bardanes (711–713). Justinian was captured and executed as was his son and co-emperor, Tiberius (706–711), thus extinguishing the Heraclian line.

Pope John VII

Philippikos' rebellion after executing emperor Justinian and his son co - emperor Tiberius in 711, extended beyond politics to religion, deposing the Patriarch Cyrus and reestablishing Monothelitism. Militarily the Bulgars reached the walls of Constantinople, and moving troops to defend the capital allowed the Arabs to make incursions in the east. His reign ended abruptly when an army rebellion deposed him and replaced him with Anastasius II (713–715).

Bulgars

Emperor Anastasius in 713 reversed his predecessor's religious policies and responded to Arab attacks by sea and land, this time reaching as far as Galatia in 714, with some success. Anastasios attempted to restore peace by diplomatic means. His emissaries having failed in Damascus, he undertook the restoration of Constantinople's walls and the rebuilding of the Roman fleet. 

A representation of Roman Fleet at Byzantium

The on death of the Caliph al-Walid I in 715, Emperor Anastasius dispatched an army under Leo the Isaurian, afterwards emperor, to invade Syria, and he had his fleet concentrate on Rhodes with orders not only to resist the approach of the enemy but to destroy their naval stores.  However the very army that had placed him on the throne (the Opsikion army) rose against him, proclaimed a new emperor and besieged Constantinople for six months, eventually forcing Anastasius to flee.

Coin of Leo III the Isaurian

The troops had proclaimed Theodosius III (715–717) as the new emperor, and once he had overcome Anastasius was almost immediately faced with the Arab preparations for the Second Arab siege of Constantinople (717–718), forcing him to seek assistance from the Bulgars. He in turn faced rebellion from two other themata, Anatolikon and Armeniakon in 717, and chose to resign, being succeeded by Leo III (717–741) bringing an end to the cycle of violence and instability, end to Twenty year's anarchy period.

Second siege of  Constantinople