The story of the Imperium Britanni-arum is hindered by inadequate sources, with reliance falling on non-contemporaries such as Eutropius, Aurelius Victor, and Orosius, who got their information from a hypothesized and unreliable source, the ‘Kai-sergeschichte’ (History of the Emperors). The ‘praise speeches’ of the Panegyrici Latini also require careful handling, and the Notitia Dignitatum can provide insight into the forces, officials, and fortifications in the region, but it does not reflect third-century realities. Numismatic evidence and archaeology instead have to step in and provide insight.
Safe and quiet in Britain
Britain had been isolated from the external problems faced by the Empire, with Hadrian’s Wall quiet and any south-eastern sea raids small in scale. This unperturbed, peripheral position saw Britain become an important source of material and manpower. The island was faced with the same social, political, and economic troubles affecting the Empire, however, which encouraged rebellion against a central government incapable of maintaining provincial security or economic integrity. In the generation prior to 286, Britain had given its allegiance to the Gallic Empire of 260-274 and hosted a revolt in 281. Such lingering disaffection made Britain a candidate for further rebellion.
The breakaway of 286 was initiated by Mausaeus Carausius. Personal details are scarce, but he was
