Breakaway regime established by Carausius, a Roman naval commander who declared himself emperor over Britain and a foothold in northern Gaul (Boulogne) in 286 during the Crisis of the Third Century.
His Gallic territory was retaken by the western Caesar Constantius Chlorus in 293, after which Carausius was assassinated by his subordinate Allectus; Britain itself was retaken by Constantius and Asclepiodotus in 296.
Broad political narrative of the Crisis-of-the-Third-Century era, including the Carausian/Britannic usurpation.