Marcus Aurelius Mausaeus Carausius (d. 293) was a Roman military commander of Gaulish origins who in 286 declared himself emperor of Britain and northern Gaul. He held power for seven years, before being assassinated by his subordinate Allectus.
Carausius was a man of humble origin, a Menapian from Belgic Gaul who distinguished himself during the western Caesar Maximian's campaign against the Bagaudae in Gaul in 284-286. This success, and his former occupation as a pilot, led to his appointment to a naval command in the English Channel, with the responsibility of eliminating the Frankish and Saxon pirates who had been raiding the northern coasts of Gaul. However, he was suspected of colluding with the pirates to enrich himself, and Maximian ordered his execution. Carausius responded by declaring himself Emperor of Britain and northern Gaul. His forces comprised not only his fleet, augmented by new ships he had built, and the three legions stationed in Britain, but a legion he had seized in Gaul, a number of foreign auxiliary units, a levy of Gaulish merchant ships, and barbarian mercenaries attracted by the prospect of booty.
Maximian prepared an invasion of Britain in 288 or 289 to oust him, but it failed. The circumstances of its failure are unclear. A panegyric to Constantius Chlorus attributes this failure to bad weather, but notes that Carausius claimed a military victory. Eutropius says that hostilities were in vain thanks to Carausius's military skill, and peace was agreed. Carausius's coins seem to agree that his rule was recognised, albeit temporarily, as legitimate. Their values were aligned with official Roman issues, and they feature the names and images of Maximian, now western Augustus, and his eastern colleague Diocletian. However, he also appears to have appealed to native British dissatisfaction with Roman rule: he issued coins with legends such as Restitutor Britanniae (Restorer of Britain) and Genius Britanniae (Spirit of Britain). A milestone from Carlisle with his name on it suggests that the whole of Roman Britain was under his control.
This situation continued until 293, when Constantius Chlorus, now the western Caesar, marched into Gaul and reclaimed it for the empire. He isolated Carausius by besieging the port of Bononia (Boulogne), and invading Batavia in the Rhine delta, securing his rear against Carausius's Frankish allies. He could not yet mount an invasion of Britain until a suitable fleet could be built. Nevertheless, Carausius's grip on power was fatally undermined. Allectus, whom he had put in charge of his treasury, assassinated him and assumed power himself. His reign would last only three years, after which he was defeated and killed by Constantius's subordinate Julius Asclepiodotus.
These events appear, in distorted form, in medieval British legend. In Geoffrey of Monmouth's legendary Historia Regum Britanniae (1136) Carausius is a Briton of humble birth, who by his courage persuades the Roman Senate to give him command of a fleet to defend Britain from barbarian attack. Once given the fleet, however, he sails around Britain stirring up unrest, and raises an army against Bassanius, king of Britain, defeats him, and sets himself up as king. Hearing of Carausius's treachery, the Romans send Allectus to Britain with three legions. Allectus defeats and kills Carausius and sets himself up as king in his place. However, he proves a tyrant, and he is overthrown by a native revolt led by Asclepiodotus, here a duke of Cornwall.
- C. E. V. Nixon & Barbara Saylor Rodgers (ed & trans), In Praise of Later Roman Emperors: The Panegyrici Latini, University of California Press, 1994, 8:6; Aurelius Victor, Book of Caesars 39:20-21; Eutropius, Abridgement of Roman History 9.21; Orosius, Seven Books of History Against the Pagans 7:25.2-4
- Panegyrici Latini 8:12
- Panegyrici Latini 10:12.1
- Panegyrici Latini 8:12.2
- Eutropius, Abridgement of Roman History 9.22
- Frere, Britannia, p. 327-328
- Panegyrici Latini 6:5, 8.6-8
- Panegyrici Latini 8:12; Aurelius Victor, Book of Caesars 39.40; Eutropius, Abridgement of Roman History 22; Orosius, Seven Books of History Against the Pagans 7:25.6
- Eutropius, Abridgement of Roman History 9.22; Aurelius Victor, Book of Caesars 39.42
- Geoffrey of Monmouth, Historia Regum Britanniae 5.3-4