Yeah – basically something like this

(6) BRITANNIC EMPIRE

(286-296 AD)

Yeah, we’re going into the Roman Empire iceberg with this one, with one of the more dubious empires in this top ten – Wikipedia refuses to dignify it as such and calls it the Carausian revolt instead, but I have a soft spot for it, if only for the name history has given it on occasion as the Britannic Empire.

However, it’s more than the name. Although its founder, Roman naval commander Carausius did not claim succession from the Roman empire but only sought to usurp part of it for himself, that part did endure for ten years or so, which is pretty impressive even by the standards of some more substantial usurpers on this list.

Also, you have to admire his audacity, which at another time or in other circumstances might have paid off – foremost among those circumstances perhaps being that his loyalist Roman opponent was the glorious Constantius, father of the even more glorious Constantine the Great.

Carausius had risen through the ranks from humble origins and was appointed to naval command in Gaul, tasked to clear the English Channel of Frankish and Saxon pirates or raiders. Instead, he collaborated with them to enrich himself – or so he was accused of doing, being sentenced to death for it. In his most audacious move, he responded with the ultimate defence – declaring himself emperor over Britain and northern Gaul.

And he had substantial forces for his empire – his own fleet of course, augmented by new ships he had built. In addition, he not only had the three legions stationed in Britain, but a legion he had commandeered in Gaul, a number of foreign auxiliary units, a levy of Gaulish merchant ships, and barbarian mercenaries.

Given such forces, it might be said that he had reasonable prospects – particularly if he had confined himself to Britain, with its more defensible position combined with naval power. To me, his biggest mistake might have been biting off more than he could chew with northern Gaul as well – where his forces were readily defeated by those of Constantius in 293, which prompted his assassination by his subordinate Allectus, who fared no better when Constantius invaded and retook Britain itself.

It might also be said that Carausius was a man before his time – and after it, with the misfortunate timing of pulling his stunt at just the wrong time. Had he been around to pull this stunt during the Crisis of the Third Century, it might have paid off – and he might have pulled it off for good if he’d been around to do it when Emperor Honorius was prepared to abandon Britain altogether, with the end of Roman imperial rule traditionally dated to 410 AD.

There was just something about Britain that inspired Roman usurpers. Governor of Britain Clodius Albinus took his shot at usurping the imperial throne in the so-called Year of Five Emperors. Another imperial usurper, Magnus Maximus also raised the standard of revolt from Britain in the fourth century – and after elevating two disappointing usurpers, the Roman army in Britain chose one of its soldiers to be yet another claimant to the throne as Constantine III in 407 AD. He actually did reasonably well for a usurper, taking the legions from Britain and setting up shop in Gaul in such a way Emperor Honorius was forced to recognize him as co-emperor from 409 to 411, until Honorius had a competent general to take a swing at him.