The third century AD is usually characterised as a time of crisis in which the Empire was plagued by civil wars, barbarian invasions, and a failing economy.
The degree to which Britain suffered directly from these horrors is debated, but it clearly had its own problems. This historical overview provides an outline of key events.
The dynasty founded by Septimius Severus ended with the death of Alexander Severus in AD 235 at the hands of his own troops. The next 50 years saw considerable internal conflict between generals who proclaimed themselves emperors, defending different parts of the Empire against barbarian invasions, and fighting with the Persian Empire. Between the death of Alexander Severus in 235 and the succession of Valerian in 253, there were 18 emperors or usurpers.
One of the most disastrous events took place in AD 260, when the Emperor Valerian was captured by the Persians. The Empire began to fragment. Britain, Gaul and Spain broke away from the central powers to form what we know today as the ‘Gallic Empire’. This mini-empire, which lasted fourteen years, had many of the trappings of the Roman state. It was brought back into the imperial fold under the Emperor Aurelian (AD 270-275), who was remarkably successful in reuniting the empire given his short reign. The decade following his death saw another string of emperors, culminating in the accession of Diocletian in AD 284.
Diocletian was a successful general and savvy politician. His rule allowed the Roman Empire to consolidate and introduced a prolonged period of political stability, but Britain still posed difficulties. In AD 286 a senior officer named Carausius revolted and declared himself Emperor of Britain and northern Gaul. The breakaway empire survived until AD 293 when Constantius Chlorus, father of Constantine I, invaded Britain from the sea, and brought it back once more under the control of the central authorities.
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