John Cantacuzenus

Fall of Byzantium: John Cantacuzenus

Previous post in this series on the fall of Byzantium is here.

Of all the emperors to rule during the last two centuries of Byzantium, John Cantacuzenus was one of the most interesting. As described in the introduction to this series, his reign faced him with an unbroken series of dilemmas that produced irrecoverable disaster for the empire. All this is made more interesting by the fact that he was eminently qualified to rule.

John Cantacuzenus was a member of an old house of the Byzantine high nobility. A distant relative of the ruling Palaeologi, he was the son of a provincial governor and himself served as governor of Thessaly. His marriage to a granddaughter of a Bulgarian tsar prepared him to deal with Byzantium’s tangled regional diplomacy. Most important, he served as second-in-command to Emperor Andronicus III, one of the most successful emperors since the recovery of Constantinople. It is important to see why, personal failings aside, he should have been an effective emperor. Only then can we perceive the eroded foundations of Byzantine power that his catastrophic reign revealed.

The Prodigal Grandson

Anatolia and southeastern Europe under Andronicus II, showing the loss of Byzantine territory to surrounding powers.

John entered the light of history amid civil war. Andronicus Palaeologus, grandson of Emperor Andronicus II, had recently been written out of the line of imperial succession because of his dissolute lifestyle. The man evidently displayed talent, however, as he maintained a loyal following. A coterie of young nobles, including John Cantacuzenus, formed around the young Andronicus, seeing in him the best hope for regeneration of the empire. Andronicus II had proven over his long reign to be an entirely unworthy emperor: he had reduced the size of the army, outsourced the navy to the Genoese and Venetians, and let even more territory slip out of the empire’s grasp. New blood was needed if the Byzantium was to avoid a rapid slide into oblivion.

The band surrounding the younger Andronicus induced their leader to flee to Adrianople in 1321, where the heir-unapparent recruited mercenaries and won the loyalty of the Thracian population by promising tax remittances. Andronicus also received the Bulgarian tsar, his brother-in-law, who lent him a cavalry troop. This act of open defiance inaugurated a civil war that would continue intermittently for the next seven years.

Andronicus brought his forces near Constantinople, where they were sufficient to intimidate his grandfather into sharing power. The latter maintaining seniority while the upstart was allowed to rule Thrace as co-emperor. This peace was broken a few months later, when a confederate of the younger emperor defected to Constantinople. There, he told Andronicus II that his grandson was plotting a coup, convincing him to resume the war. The younger emperor was quickly able to win the loyalties of the major cities and regions outside Constantinople. Fighting only lasted a few months before he was able to bring his grandfather to nearly identical terms as before.

Andronicus III Palaeologus

The recent round of hostilities had done little more than reveal the fractiousness of court politics. The young co-emperor was formally crowned Andronicus III in 1325, and as one of his first official acts rewarded John Cantacuzenus with the appointment as Grand Domestic. This position was equivalent to commander-in-chief of the army, and John quickly proved his worth by checking Bulgarian and Turkish incursions. From then on, Cantacuzenus would always be by the side of his emperor, accompanying him at court or on campaign.

An uneasy peace was maintained between the Andronici in the meantime. Differences in governing style did cause tensions: when the Ottoman Turks besieged Prusa in 1326, the elder Andronicus forbade his grandson from going to its relief. This inexplicable indolence allowed the Ottomans to conquer their first major city, which they turned into the first capital of their rapidly-growing state. Mutual distrust between the two emperors continued to grow, until they were back at war in late 1327.

The balance of power was much as it had been five years earlier—if anything, Andronicus II was even less popular now. The kings of Serbia and Bulgaria, realizing they could profit by protracting the civil war, threw their lots in with the senior emperor. As it happened, foreign intervention proved irrelevant. Andronicus II was immensely unpopular by that time, and his co-emperor rapidly subdued all territory outside the capital. In the spring of 1328, Andronicus III snuck into Constantinople with a small body of picked troops and forced his grandfather to abdicate. The latter would spend the rest of his life as a monk; the former as sole emperor.

This was the first civil war Byzantium had endured since the recovery of Constantinople, and it sounded ominous notes for the future. Already visible were the endemic factionalism of the court and the maneuverings of the Slavic powers to exploit it. The war had not been devastating—there were no major battles—but bribes to foreign rulers, troop levies, and promises of tax relief had made it expensive. In the meantime, the empire was poised for a brief resurgence.

The Grand Domestic

Ottoman expansion under Orhan (1326-1361).

The reign of Andronicus III did not begin auspiciously. The Ottoman bey Orhan had taken advantage of the recent civil war to besiege the major cities of Nicaea and Nicomedia (modern Izmit and Iznik). The emperor and his Grand Domestic led a relief army in person, but their failure allowed the Turks to seize the rest of Byzantine territory in Asia over the next ten years. From then on, Andronicus continued the post-recovery policy of focusing more on defending Byzantine territory in Europe than in Asia, to the long-term detriment of both. As if to compensate, he would spend the rest of his reign on campaign, proving an energetic and dogged commander.

Following the defeat outside Nicomedia, Andronicus and John took up the challenges facing them in Europe: they checked the Bulgarians, stabilized the frontier with Serbia, and recovered several Aegean islands from the Genoese. Through a combination of force and diplomacy, they began clawing back territory from the various Greek and Latin barons of mainland Greece. A major win came in 1335 when the Despot of Epirus died, leaving a young heir. Andronicus and John appeared soon after at the head of the imperial army to appoint a governor. This was a moral as well as territorial victory: one of the post-1204 successor states claiming independent legitimacy had finally been brought back into the empire.

John Cantacuzenus had meanwhile tasked on the domestic front as well. Andronicus commissioned him to reform the judicial system and end the corrupt practices of the courts. If the Byzantine state was to be restored to its true glory, it would have to win back the trust and confidence of its own people. The task was probably too immense to be completed in a single generation, but the new system John implemented would last until the end of the empire.


Andronicus came down with a sudden illness in the spring of 1341 and died a few days later. He had had a mixed reign: significant victories that were causes for hope, balanced by setbacks that revealed fundamental weakness. But behind him he left a healthy, young heir and a competent, old hand in John Cantacuzenus. Preparations were already underway to consolidate his gains and continue his conquests in Greece. Reform of the administration continued apace. It looked as if things might finally be on the upswing for the empire.

No such luck. The next thirteen years would face John with a series of unmanageable predicaments. The first of these was upon him.