Constantius II

Constantius II: The Survivor of His Own Dynasty

When Constantine the Great died in 337, the empire's most dangerous place to stand was inside his family. Within months, two of the dead emperor's half-brothers and seven of his nephews had been killed. The official story blamed mutinous soldiers. Ammianus Marcellinus, the best historian of the century, blamed the twenty-year-old son who emerged from the killing with the eastern half of the Roman world. Constantius II then ruled for twenty-four years, outlasted two brothers, two usurpers, one executed cousin and a Persian king's repeated invasions, and died in bed of a fever while marching to fight the last living male relative he had.

A Caesar at Seven

Flavius Julius Constantius was born on 7 August 317 at Sirmium in Pannonia Inferior, the son of Constantine the Great and Fausta, daughter of the emperor Maximian. On 8 November 324, at the age of seven, his father made him Caesar. He was raised inside the imperial apparatus from before he could reasonably understand it — a childhood that produced the two traits every source agrees on: administrative diligence and a suspicion of everyone.

337

On Constantine's death, Constantius and his brothers Constantine II and Constans became Augusti. Almost immediately the descendants of Constantine's father by his other wife, Flavia Maximiana Theodora, were eliminated — among them the uncles Julius Constantius and Flavius Dalmatius and seven cousins. Two boys were spared: Constantius Gallus and Julian. Both would later be made Caesar by the man who had probably ordered their family killed, and one would succeed him.

At Sirmium the surviving brothers divided the world. Constantius took the East — Constantinople, Thrace, Asia Minor, Syria, Egypt, Cyrenaica — which meant he also took the Persian frontier, the hardest military assignment in the empire.

Shapur

For essentially his entire reign, from 337 to 361, Constantius faced Shapur II's Sassanid invasions. He won at Narasara in 337, killing Shapur's general Narses. Thereafter the war settled into the grinding pattern of Mesopotamian siege warfare around Nisibis, Singara and Amida. At Nisibis the Persians breached the wall and Shapur failed to exploit it; the siege was lifted.

Constantius never conquered anything in the East and is not remembered as a great captain there. But across a quarter-century he repelled every major Persian invasion, and the frontier he inherited was substantially the frontier he left. In a strategic situation that offered no possibility of decisive victory, he chose attrition and did not lose.

Mursa Major

The West destroyed itself without his help. Constantine II died in 340 near Aquileia fighting Constans over territory; Constans held the western two-thirds until the usurper Magnentius had him killed in January 350.

Constantius refused to accept Magnentius as a colleague and fought him for three years. The Battle of Mursa Major in 351 was a victory, and it is described as one of the largest and bloodiest battles ever fought between two Roman armies — a description that is also an indictment, since the manpower burned there was manpower unavailable against Persians and Germans. Magnentius was beaten finally at Mons Seleucus in 353 and killed himself on 10 August. Constantius was sole emperor.

He fought on the northern frontiers too, defeating the Alamanni in 354 and driving the Sarmatians and Quadi out of Pannonia and Moesia Inferior in 357 before counter-attacking across the Danube. In April and May of 357 he visited Rome, the only time he saw the old capital as emperor.

The Two Cousins

Ruling everything alone was beyond one man, so he reached for the family he had nearly extinguished. Gallus was made Caesar for the East in 351 and married to Constantius's sister Constantina as an insurance policy. Gallus governed with violence and corruption, was summoned west in 354 and executed at Poetovio. The detail that survives is characteristic of the court: Constantius rescinded the death order, and the eunuch Eusebius delayed the countermand until it was too late.

On 6 November 355 he elevated Julian, his last surviving male relative, and sent him to Gaul. Julian beat the Alamanni, and in 360, when Constantius demanded his troops for the eastern war, the legions proclaimed Julian Augustus. Constantius tried persuasion, then marched. He fell ill at Mopsuestia in Cilicia and died on 3 November 361, aged 44 — having, the sources say, accepted baptism from the Semi-Arian bishop Euzoius of Antioch and named Julian his rightful successor. He was buried in the Church of the Holy Apostles in Constantinople.

The Theologian Emperor

His religious policy was the most consequential and least successful part of his reign. He is usually called an Arian, which is imprecise: he championed Semi-Arianism, a compromise between the Arian position and the Nicene Creed, and convened council after council trying to impose it on the church. A.H.M. Jones observed that "the theologians whose advice he took were ultimately discredited" and that none of his councils were ever recognised as ecumenical — so he is remembered as an emperor who imposed his will on doctrine rather than one who restored unity.

Against paganism he legislated ferociously: laws from the 350s prescribed death for performing or attending sacrifices and for the worship of idols; temples were closed and the Altar of Victory removed from the Senate house. Yet he preserved the priestly colleges, the Vestal Virgins and the pagan schools, remained pontifex maximus, and even ordered a priest elected for Africa. He restricted Jewish business and slave-owning, banned Jewish-Christian marriage, and confiscated the property of converts to Judaism — measures scholars read as economic protectionism as much as theology.

He married three times: an unnamed daughter of Julius Constantius; Eusebia of Thessalonica; and finally Faustina in 361, who bore a posthumous daughter, Constantia, later married to the emperor Gratian.

Why Constantius Is Called a Genius

Here the honest answer must begin by conceding that the ancient world did not call him one. Ammianus Marcellinus, who lived through his reign, described him as "conscientious but vain and stupid... an easy prey to flatterers. He was timid and suspicious." That is close to the opposite of a claim of genius, and it comes from the most authoritative source available.

What can be argued is a talent for political survival and administrative persistence that borders on the uncanny. He held the most exposed position in the empire for twenty-four years, fought Persians in the east and Germans on the Danube and Romans in the middle, and died undefeated in the field. He understood, as few emperors did, that his real problem was structural — that one man could not personally command three frontiers — and he tried repeatedly to solve it through delegation, even to a family he had cause to fear. Eutropius's assessment is warmer than Ammianus's: "a man of remarkably tranquil disposition, good-natured, trusting too much to his friends and courtiers... gentle" except when he suspected a threat to his rule, with fortune "more to be praised in civil than in foreign wars." Modern numismatists Kent and Hirmer note that he "has suffered at the hands of unsympathetic authors" and that most contemporaries "seem in fact to have held him in high esteem, and he certainly inspired loyalty."

The counter-case is heavy. His doctrinal project failed completely and left the church more divided. Mursa Major consumed Roman armies that the frontiers needed. He executed one cousin through a bureaucratic accident of his own court's making and drove the other into revolt. And DiMaio and Frakes are surely right that "Constantius is hard for the modern historian to fully understand both due to his own actions and due to the interests of the authors of primary sources for his reign." He is better described as formidable than brilliant.

Legacy

He is the emperor between two more interesting ones — his father, who Christianised the empire, and his cousin Julian, who tried to un-Christianise it and failed. But the state Julian inherited was intact, solvent and defended, which was not inevitable, and the eastern half that Constantius spent his life holding together would outlive the western half by a thousand years. His last recorded act was to name as his heir the man marching to overthrow him, which may be the single most sensible decision of the fourth century.