Born in obscurity in Dalmatia circa 244 CE, Diocles may have been either a freedman of a senator named Anullinus or the son of a scribe who was himself a freedman (Eut. Brev. 9.19; Epit. Caes. 39.1; Lact. Mort. 9.11). Rising through the ranks of the army, he became Dux Moesiae (“Roman provincial leader”) in modern Bulgaria before becoming the commander of the “imperial bodyguard” (protectores domestici) of Emperor Numerian during the Persian campai…