P. J. Casey, Carausius and Allectus: The British Usurpers (Yale University Press, 1996)
The political history of Roman Britain is not well-documented, and among its more shadowy reaches is the ten-year period (286-296 A.D.) during which the island formed an effectively independent realm under the "emperors" Carausius and Allectus. The literary evidence for these figures is windy and exiguous, but they left behind large numbers of coins of many different types. P. J. Casey, an archeologist and numismatist, believing that coinage, properly interpreted, can make significant contributions to the historical record, has taken up the challenge of reconstructing the skeleton, if not the torso, of the Carausian regime.
The greatest part of the book is not a true narrative (which would take up only a few pages) but rather an analysis of raw data from speeches, chronicles, coins and excavations. The presentation is admirably lucid, but readers who are easily bored by tables of the distribution of mint marks may lose the thread.
Casey's efforts produce a convincing outline. The story begins with the rebellion of Carausius, a Roman naval commander assigned to chase pirates on the Gallic coast but accused of snatching recovered booty for his own purse. Like all rebels, he called himself "emperor" and claimed a legitimate place in the imperial government, going so far as to portray on his coins "brother" emperors who never deigned to take public notice of him except as a "rebel".
The new regime established itself in Britain, firmly enough to throw back the first expedition sent against it. On the continent, it initially held substantial territories, lost them to the "legitimate" authorities, then regained a portion of them again. After seven years of rule, Emperor Carausius was assassinated by his treasurer Allectus, a yet more obscure figure who faced and was defeated by the army of the Caesar Constantius (father of the Constantine the Great). Credit for the campaign should go to one of Constantius' subordinates, but the official panegyrists who are practically our only source of information preferred to give all credit to the Caesar.
Unfortunately, the outline cannot be fleshed out with much detail. Even major incidents, such as the failure of the Roman authorities' first attempt at reconquest, are known only by inference. Through a dim haze we glimpse the clash of armies and fleets in what must have been "interesting times", but we can barely see who is fighting and cannot at all say why.
Appended to the main body of the work are excurses on three more or less related topics: Roman naval warfare (about which not much can be said), the mysterious "Carausius" coinage that appeared in the 350's (which some historians, though not Casey, attribute to an otherwise unknown "Carausius II") and - the most entertaining portion of the book - the legends that grew up around Carausius' name in the Middle Ages. Perpetuated and elaborated well into the 1700's, this pseudo-history transformed the Roman rebel into an Irishman, a Welshman, a Dutchman, a peacemaker between Picts and Scots, a savage invader of Scotland, the ancestor of a noble Venetian family and a founding father of the English navy. In this unexpected way, the name of this shadow of an emperor has lasted to our own day, when those of many once famous figures now are shadows themselves.