https://finds.org.uk/news/story/97
Until this discovery was made some scholars doubted the historical significance of Domitianus who is named just twice in the historical sources. The Oxfordshire coin provides archaeological evidence suggesting that he successfully proclaimed himself emperor of a breakaway part of the Roman Empire during the reign of Aurelian (AD 270-5).
https://en.wikipedia.org/wiki/Domitian_II
Domitian II (Latin: Domitianus) was a Roman soldier of the mid 3rd century who was acclaimed emperor, probably in northern Gaul in late 270 or early 271, and struck coins to advertise his elevation. It is now generally assumed that this man is to be equated with the Domitianus who is twice mentioned in the literary sources as a significant figure in the politics of the age, but on neither occasion as an outright contender for the Imperial throne.
Given that his reign lasted for, at best, only a few weeks after his acclamation and he does not seem to have secured significant military or political support, Domitianus is more properly categorized as a Roman usurper rather than an emperor. His attempted coup should also be understood in the context of the troubled later history of the Gallic Empire rather than that of the Empire as a whole.
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