Isn’t this Carausius guy one of the real-life historical figures whose stories were morphed together over the centuries to form the King Arthur legend?
Lucius Artorius Castus was a Roman soldier (2nd or 3rd century) who is sometimes seen as a historical figure who became one source for the story of Arthur.
Not exactly, Geoffrey of Monmouth (From whom the Arthurian legend is believed to orginated from) created a legend around him which suggested he was British-Born (he was in fact a Gaul, but Gaul and Britain were so similar at this point that the difference is hardly relevant) and that he seized control of Britain from Bassianus (Caracalla) who lived and died before Carausius was even born.
In fact Carausius was in charge of the Classis Britannica (a large Roman Fleet based in Britain) and rebelled against Diolcletian’s co-emperor Maximian in 286, he successfully resisted Rome’s attempts to to re-conquer Britain (which may explain Geoffrey of Monmouth’s attempt to build a pro-English/British legend around him juxtaposed with a legendarily evil Emperor like Caracalla) until he was assassinated by his own treasurer Allectus, who lost the Britain back to Rome in 293.
Still quite an interesting character though. He is responsible for the earliest coins minted in London, and I’ve had the privilege of handling many of them (not from this hoard though)...