Constantine V vs John VI Kantakouzenos

Constantine V convened the Council of Hieria, which formally condemned the veneration of icons as idolatry. This council established iconoclasm as official Byzantine Church doctrine, intensifying the religious controversy that divided the empire.

Following the Council of Hieria, Constantine V intensified persecution of icon venerators. Monks were imprisoned, executed, or forced to marry. Monasteries were confiscated and converted to barracks or secular use. This policy deepened the iconoclast schism.

Constantine V led nine major campaigns against the Bulgarian Empire, achieving several victories including the Battle of Marcellae (759) and the Battle of Anchialus (763). These campaigns temporarily weakened Bulgaria but did not destroy it.

Constantine V oversaw the restoration of the Aqueduct of Valens, which had been damaged by the Avars. The repaired aqueduct restored water supply to Constantinople, improving urban infrastructure and public health.

Constantine V died while on campaign against the Bulgars. His death occurred during a military expedition, and he was succeeded by his son Leo IV. His campaigns had temporarily checked Bulgarian expansion but left the empire exhausted.

John VI Kantakouzenos supported the Hesychast movement in the Orthodox Church, which emphasized contemplative prayer and divine light. He convened councils that affirmed Hesychast theology, leading to the condemnation of its opponents and shaping Orthodox spirituality.

John VI Kantakouzenos allied with the Ottoman Sultan Orhan I, marrying his daughter Theodora to Orhan. The alliance provided Ottoman military support in the civil war but allowed the Ottomans to establish a foothold in Europe, including the capture of Gallipoli in 1354.

John VI Kantakouzenos was crowned emperor after winning a six-year civil war against the regency of John V Palaiologos. His victory was achieved with Ottoman support, which set a precedent for Ottoman interference in Byzantine affairs.

John VI Kantakouzenos abdicated the throne after John V Palaiologos recaptured Constantinople with Genoese support. He retired to a monastery, taking the monastic name Joasaph, where he wrote a history of his times, the 'Historiai', a key source for 14th-century Byzantium.

John VI Kantakouzenos wrote the 'Historiai', a detailed historical account of the Byzantine Empire from 1320 to 1356. The work is a primary source for the period, covering the civil wars, Ottoman expansion, and religious controversies, though it is biased in favor of the author.