Domitius Domitianus aureus - $1.6m

A gold coin of an obscure, ill-fated Roman usurper led the way in elite auctions by Numismatica Ars Classica in late May. Graded Ch AU★, 5/5 Strike and 4/5 surface, it raced past its pre-auction estimate and made $1.63 million. Lucius Domitius Domitianus launched his rebellion from Egypt in 297 AD, seizing control of Alexandria and the Nile Delta. Capitalizing on local grievances against Diocletian's high taxes, he declared himself Augustus and minted his own coins. Its believed to be one of three aurei in private hands.

"One of the great ironies of Roman coinage is that some of the most valuable coins are of emperors who most people have never heard of,"

The revolt of Domitius Domitianus in Egypt interrupted the grain supply to Rome and opened the possibility of Persian (Sasanian) invasion. For about 8 months Domitianus controlled Alexandria and its mint, striking aurei and folles, as well as a series of pre-reform imperial Greek denominations. Diocletian personally led an expedition to Egypt to quell the rebellion. Diocletian retook most of the lost territory by December 297, which is when Domitianus died.

The rebellion was briefly sustained by Domitianus' corrector (designated successor), Aurelius Achilleus. Diocletian laid siege to Alexandria, ultimately recapturing the city and brutally crushed the final resistance in March 298. Diocletian was Roman emperor from 284 until his abdication in 305. Diocletian was unique in Roman imperial history for choosing retirement. He would die in 313 CE as a farmer growing cabbages.