Carausius and Allectus 286 AD to 296 AD


Bringing Order to Chaos: The Armies of Diocletian

Maximian, as Emperor of the West, had his own military problems. Of these, the most intractable was presented by Carausius, a rebellious admiral of the British Channel fleet. Irrepressible, Carausius was for some time endured by the two “Augusti” as a kind of supernumerary colleague in Britain and north Gaul. Eventually, Maximian’s “Caesar”, Constantius, drove him from Boulogne and, continuing the war against Carausius’ murderer and successor Allectus, restored Britain to its former allegiance.

Carausius provides an excellent example of a secessionist typical in the third century. Like other secessionists he did not plan to establish an independent state. Rather, he desired to become emperor, and he styled himself as such.

Born in northern Belgium, Carausius learned a trade as a seafaring merchant. He entered the military and served with Maximian in Gaul in 285 against the Bagaudae. Carausius then served with distinction, effectively ending the Saxon pirates’ menacing of the English Channel. Maximian accused him of allowing pirates to freely raid the northern Gallic coastline, seizing booty, and then capturing them on their return and keeping the stolen goods. Fearing execution, Carausius seized northern Gaul and the troops there supported him. He then won the support of the troops in Britain and made the island his major base.

Carausius consolidated his position in Britain and secured the region with his fleet. Maximian attempted to retake Britain by building a fleet. This invasion either failed or never took place, since several years later orators did not make reference to this invasion. Carausius did lose northern Gaul in 287, but regained it in 288–289. This blow to Maximian may have forced Diocletian to appoint Constantius as a junior partner or Caesar.

Carausius, calling himself emperor and controlling Britain, undertook a coinage reform, issuing pure silver coins before the central government under Diocletian undertook the same reform. Diocletian may have used Carausius’ reform as a model for his own. He campaigned in northern Britain against the Picts and repaired Hadrian’s Wall. He attempted to ingratiate himself with Maximian and Diocletian during the early 290s by assuming their praenomens (first names) Valerius and Aurelius. He issued coins with all their portraits with the legend Carausius and his brothers. The senior emperors did not reciprocate, although they may have made a tentative peace agreement. When Diocletian nominated Constantius as Caesar, Carausius abandoned this policy.

Constantius began a systematic reduction of cities controlled by Carausius of northern Gaul beginning in 292–293. Constantius’ important siege and capture of Boulogne dealt a severe blow to Carausius. Although not present, the loss of Boulogne deprived Carausius of his most important naval base in northern Gaul. Carausius was assassinated by his lieutenant Allectus. Constantius now began to build his naval forces, but inland, since Allectus still controlled the English Channel. Constantius launched his invasion of Britain in a two-pronged front led by Asclepiodotus westward at the Isle of Wight, and Constantius northeast near the Thames estuary. Constantius’ fleet was delayed by a storm but Asclepiodotus defeated and killed Allectus.

Carausius, and later Allectus, continued to identify themselves as emperors and viewed their dominion as the Roman Empire. The success of Carausius lay in his ability to be recognized as a Roman emperor by the people of Britain, and not as a secessionist. Carausius, and later Allectus, failed in their aims because the full weight of the empire was against them.



A major usurper during the late 3rd century A.D., who controlled Britain and much of modern Gaul. Carausius had humble origins in Messapia but won fame in the campaigns of Emperor Maximian against the Franks and the Bagaudae in 286. Looking for a competent officer to eradicate the Frank and Saxon pirates in the Channel, Maximian chose Carausius.

He proved a brilliant admiral but was accused of keeping recovered plunder for his own use and of pressing captured pirates into his own fleet. Sentenced to death, he sailed to Britain in late 286 or early 287, declaring himself independent of imperial control. The Britons greeted him cheerfully and helped him to consolidate his power. Carausius soon began to seize large parts of the Gallic coast. In April of 289, Maximian finally moved against him, only to suffer defeat at Carausius’ hands. The emperor was reduced to making a treaty with him instead. Carausius declared his triumph, issuing at first an irregular and then an imperial coinage, with the presumptuous words: “Carausius and his brothers, Diocletian and Maximian.” Ironically, Carausius provided the TETRARCHY exactly what it needed in Britain. He resisted the incursions of the Picts, repaired Hadrian’s Wall and kept the regions secure. His independence, however, could not be tolerated, and Diocletian waited until the time was ripe to strike.

In 293, Emperor Constantius I Chlorus, Diocletian’s junior, launched a massive assault on Carausius’ holdings in Gaul. The port of Gesoriacum (Boulogne) was blockaded by Constantius, while Carausius’ main fleet remained in Britain to repel an invasion. The city fell, but just barely; reinforcements were prevented from arriving by a great mole stretched across the harbor. These initial setbacks were compounded as Constantius cleared the entire region of Gaul. Having lost his continental territories, Carausius suffered other political difficulties as well, until his chief minister, ALLECTUS, became disenchanted and killed him in 293, taking over his ships, troops and his claim to supremacy in Britain.

ALLECTUS (fl. late 3rd century A.D.)

A rationalis or minister of finance to the usurper CARAUSIUS. In 293, his ambitions led him to assassinate his master and seize power for himself in Britain and in some provinces of Gaul. Allectus was apparently a gifted soldier and sailor, and his rule lasted for three turbulent years. Sometime around 295-296, Constantius I (Chlorus) resolved to end the usurpation of power and set sail with two fleets to Britain, commanding one fleet and entrusting the other to Praetorian Prefect Asclepiodotus. After losing his enemy in a fog, Allectus disembarked his fleet and prepared for battle. Near Hampshire, Asclepiodotus fought and routed Allectus, and shortly thereafter Allectus was killed. Constantius entered London and thus found a power base for himself and his son, Constantine the great.

Casey, P. J. 1994. The British usurpers: Carausius and Allectus. New Haven.








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