His military activity, and policy of settling Christian populations from the Arab frontier in Thrace, made Byzantium's hold on its Balkan territories more secure.

[6] To celebrate the coronation of his son, Leo III introduced a new silver coin, the miliaresion; worth one-twelfth of a gold nomisma, it soon became an integral part of the Byzantine economy.

[7][8][9][10] Historical accounts of Constantine make reference to a chronic medical condition, possibly epilepsy or leprosy; early in his reign this may have been employed by those rebelling against him to question his fitness to be emperor.

[20] Like his father Leo III, Constantine supported iconoclasm, which was a theological movement that rejected the veneration of religious images and sought to destroy those in existence.

However, it refused to endorse all of Constantine's policies, which were influenced by the more extremist iconoclasts and were possibly critical of the veneration of Mary, mother of Jesus, and of the saints.

The council confirmed the status of Mary as Theotokos (Θεοτόκος), or 'Mother of God', upheld the use of the terms "saint" and "holy" as legitimate, and condemned the desecration, burning, or looting of churches in the quest to suppress icon veneration.

[25][26][27] The Council of Hieria was followed by a campaign to remove images from the walls of churches and to purge the court and bureaucracy of iconodules, however, the accounts of these events were written much later than they actually occurred, and by often vehemently anti-iconoclast sources, therefore their reliability is questionable.

However even his c. 808–809 hagiography, the Life of St. Stephen the Younger, connects his execution more to treason against the Emperor, and indeed his punishments reflect those typically associated with an enemy of the state.

On becoming aware of an iconodule-influenced conspiracy directed at himself, Constantine reacted uncompromisingly; in 765, eighteen high dignitaries charged with treason were paraded in the hippodrome, then variously executed, blinded or exiled.

[32] According to later iconodule sources, for example Patriarch Nikephoros I of Constantinople's Second Antirrheticus and treatise Against Constantinus Caballinus, Constantine's iconoclasm had gone as far as to brand prayers to Mary and saints as heretical, or at least highly questionable.

[33] However, the extent of coherent official campaigns to forcibly destroy or cover up religious images or the existence of widespread government-sanctioned destruction of relics has been questioned by more recent scholarship.

[38] Assiduous in courting popularity, Constantine consciously employed the hippodrome, scene of the ever-popular chariot races, to influence the populace of Constantinople.

In this he made use of the 'circus factions', which controlled the competing teams of charioteers and their supporters, had widespread social influence, and could mobilise large numbers of the citizenry.

Iconoclasm was not purely an imperial religious conviction, it also had considerable popular support: some of Constantine's actions against the iconodules may have been motivated by a desire to retain the approval of the people and the army.

The monasteries were exempt from taxation and monks from service in the army; the Emperor's antipathy towards them may have derived to a greater extent from secular, fiscal and manpower, considerations than from a reaction to their theology.

In those provinces closest to the seat of government this measure increased the number of stratēgoi and diminished the resources available to any single one, making rebellion less easy to accomplish.

This force was designed to form the core of field armies and was composed of better-drilled, better-paid, and better-equipped soldiers than were found in the provincial themata units, whose troops were part-time soldier-farmers.

[53] In 746, profiting by the unstable conditions in the Umayyad Caliphate, which was falling apart under Marwan II, Constantine invaded Syria, captured Germanikeia (his father's birthplace) and recaptured the island of Cyprus.

Constantine retired to Bithynia to avoid the disease and, after it had run its course, resettled people from mainland Greece and the Aegean islands in Constantinople to replace those who had perished.

The eastern campaigns failed to secure concrete territorial gains, as there was no serious attempt to retain control of the captured cities, except Camachum (modern Kemah), which was garrisoned.

Additionally, the deliberate depopulation of the region beyond the eastern borders created a no-man's land where the concentration and provisioning of Arab armies was made more difficult.

[55][56][57][58] With Constantine militarily occupied elsewhere, and the continuance of imperial influence in the West being given a low priority, the Lombard king Aistulf captured Ravenna in 755, ending over two centuries of Byzantine rule in central Italy.

[61] Constantine sent a number of unsuccessful embassies to the Lombards, Franks and the papacy to demand the restoration of Ravenna, but never attempted a military reconquest or intervention.

This influx of settlers, allied to an active re-fortification of the border, caused concern to the Empire's northern neighbour, Bulgaria, leading the two states to clash in 755.

The cumulative effect of Constantine's repeated offensive campaigns and numerous victories caused considerable instability in Bulgaria, where six monarchs lost their crowns due to their failures in war against Byzantium.

However, the hostile reaction of the Roman Church and the Italian people to iconoclasm had probably doomed imperial influence in central Italy, regardless of any possible military intervention.

Typical of this demonisation are the descriptions of Constantine in the writings of Theophanes the Confessor: "a monster athirst for blood", "a ferocious beast", "unclean and bloodstained magician taking pleasure in evoking demons", "a precursor of Antichrist".

Following a disastrous defeat of the Byzantines by the Bulgarian Khan Krum in 811 at the Battle of Pliska, troops of the tagmata broke into Constantine's tomb and implored the dead emperor to lead them once more.

[76] The life and actions of Constantine, if freed from the distortion caused by the adulation of his soldiers and the demonisation of iconodule writers, show that he was an effective administrator and gifted general, but he was also autocratic, uncompromising and sometimes needlessly harsh.

In contrast, the author indicates that iconodules had to make accommodations with imperial iconoclastic policies, and even bestows on Constantine V the conventional religious acclamations: 'Guarded by God' (θεοφύλακτος) and 'Christ-loving emperor' (φιλόχριστος βασιλεὺς).