IMP C C VAL DIOCLETIANVS AVG, radiate, draped and cuirassed bust right / CONCORDIA MILITVM, Diocletian standing right, holding parazonium, receiving Victory from Jupiter standing left, holding sceptre. Mintmark HE/XXI. 21mm, 1.96 grams. Hercaclea mint. RIC 284

Diocletian (Gaius Aurelius Valerius Diocletianus), born around 244 AD in Dalmatia, was Roman emperor from 284 to 305 AD and is best known for fundamentally reshaping the structure of the Roman Empire. Rising from humble origins as a soldier, he came to power after the assassination of Emperor Numerian and swiftly secured his position by defeating rival claimants. Recognizing the empire’s unmanageable size and constant instability, Diocletian introduced the Tetrarchy in 293 AD—dividing rule among two senior emperors (Augusti) and two junior emperors (Caesars)—to ensure more efficient governance and defense.

Diocletian also carried out extensive military, administrative, and economic reforms, including efforts to stabilize the currency and curb inflation with the Edict on Maximum Prices. A staunch traditionalist, he launched the Great Persecution of Christians in 303 AD, the last and most severe wave of anti-Christian repression in the Roman Empire. In a highly unusual move for a Roman emperor, Diocletian voluntarily abdicated in 305 AD and retired to his palace in what is now Split, Croatia, where he lived until his death around 311 AD. His reign marked the end of the Crisis of the Third Century and laid the foundation for the later Byzantine Empire.