Portrait of the Emperor Postumus on a double sesterce (a brass coin, enlarged).

Shakespeare's names are highly significant to understanding the characters to which they are attached. It is usually assumed that Posthumus is a name Shakespeare improvised for his hero in Cymbeline, but he would have found it in most chronicles of Britain which he used as sources, because it was that of a humble man who rose to be a provincial governor in Northern Europe, and then rebelled and declared himself Emperor (260-268 A.D.) and broke Britain off from the Roman Empire. His resistance to Rome matches similar challenges to Roman supremacy which Shakespeare celebrates in such plays as Cymbeline, King John, and Henry VIII. As a warrior who joins his brothers-in-law in fighting a Roman army in Shakespeare's Cymbeline, Posthumus is aptly named in anticipation of the future northern emperor.

Attribution: Classical Numismatic Group, Inc. http://www.cngcoins.com Picture and some data courtesy of the Yorck Project, under Creative Commons Attribution-Share- Alike License (Wikipedia). Originally uploaded by CharlesS in 2004.