Diocletianus

Diocletianus, commonly known simply as Diocletian, was a Roman emperor who ruled from 284 to 305 CE. Born as Diocles in about 244 in the Dalmatian region, he rose through the military and provincial ranks and, after the death of Carus, was proclaimed emperor by his troops. He and his colleague Maximian established the Tetrarchy, appointing Galerius and Constantius as Caesars, in an effort to stabilize the empire and secure a smooth succession.

Diocletian implemented wide-ranging reforms. He reorganized administration by creating dioceses and further dividing provinces, and he separated civil authority from military command. The tax system was reformed, provincial governance expanded, and monetary policy was adjusted to curb inflation. He also strengthened frontier defenses and oversaw large-scale building programs, including roads, fortifications, and urban projects, to bolster imperial reach and control.

Religiously, Diocletian promoted traditional Roman cults and initiated the Great Persecution (303–311), ordering the destruction of some churches and the suppression of Christian practices. The policy softened after Galerius issued a toleration edict in 311, but the persecution remained a defining aspect of his religious policy during his later years.

In 305, Diocletian and Maximian abdicated, an unusual move that transferred power to the remaining Augusti and Caesars and marked the formal start of the Tetrarchic transition. Diocletian retired to his palace in Dalmatia and died there in 311. His reign established a model of imperial governance that influenced late antiquity, with the Tetrarchy shaping administrative and political practices for several decades even as it eventually gave way to new power structures.