Constans II ruled for twenty-seven years as the Arab conquests took Egypt and Africa, moved his court to Sicily, and was murdered in his bath there.
Constans II became emperor at eleven in 641, in the wreckage that followed his grandfather Heraclius's death, and ruled for twenty-seven years — the whole of the period in which the Arab conquests took Egypt, then Africa, and turned the Mediterranean into a contested sea.
He is the emperor who had to work out how a Roman empire operates after losing half of itself, and much of what he improvised became permanent: soldiers settled on the land in the surviving provinces, a fleet rebuilt, a religious argument suppressed rather than resolved.
In 663 he moved his court to Syracuse in Sicily, which the capital never forgave, and was murdered there five years later.
He was born in 630, the son of Constantine III, and came to the throne as a boy after his father died within months of Heraclius and his uncle Heraklonas was deposed and mutilated.
His accession speech to the senate — reported by Theophanes and probably written for him — is a striking document: an eleven-year-old emperor apologising for his family's murders and asking the senate to govern with him.
The empire he inherited had already lost Syria, Palestine and most of Egypt. Alexandria fell for the last time in 646, when he was sixteen.
The tradition is hostile, and the reason is specific: he had his brother Theodosius killed in 660 and he moved the capital west, and the Constantinopolitan sources never forgave either.
They call him Pogonatos, the bearded, and describe him as harsh, obstinate and haunted — Theophanes has him dreaming of his murdered brother handing him a cup of blood. What the same sources cannot conceal is that he campaigned personally in the Balkans, in Armenia and in Italy, and that the state survived a generation that ought to have finished it.
The move to Sicily is the decision everything turns on. Read as desertion it is contemptible; read as strategy it is arguable — the western Mediterranean was still defensible, Africa was not yet lost, and an emperor in Syracuse was closer to the Lombards, the Berbers and the sea than one in Constantinople. He was killed before it could be judged.
The Arab advance was continuous. Egypt was gone by 646, the fleet was beaten at the Battle of the Masts off the Lycian coast in 655 — the first great Arab naval victory — and only the Muslim civil war after 656 gave the empire a decade of relief.
He used it. The remaining provinces were reorganised with soldiers settled on land they had reason to defend, a system his successors developed into the themes, and the Balkans were campaigned in for the first time in decades.
On religion he issued the Typos in 648, which did not settle the Monothelete controversy but forbade anyone to discuss it — and then persecuted those who would not stop, including Pope Martin I and Maximus the Confessor, both of whom died in exile after mutilation. It is the least defensible part of his reign and it did not work.
He is the emperor of the worst decades, and the empire came out of them still functioning, which is not a small thing to have presided over.
The provincial reorganisation he began is the foundation of the theme system that defended Anatolia for four centuries, and the fleet he rebuilt is what held the sea approaches to the capital until Greek fire arrived under his son.
His murder in a Sicilian bathhouse, and the speed with which his son crushed the usurper and brought the court home, is a fair summary of how the experiment ended: the strategy died with him and Constantinople stayed the capital.