Diocletian vs Gallienus

Diocletian created the Tetrarchy, dividing the Roman Empire into four administrative regions ruled by two senior emperors (Augusti) and two junior emperors (Caesares). This system aimed to improve governance and defense, and stabilize imperial succession.

Diocletian reorganized the Roman provinces into smaller units (dioceses) grouped into four prefectures, separating civilian and military authority. This reform improved tax collection and administration, but also increased bureaucracy.

Diocletian issued the Edict on Maximum Prices, setting price ceilings on over 1,000 goods and services to combat inflation. The edict was largely ineffective and led to black markets, but demonstrated the state's attempt to control the economy.

Diocletian issued a series of edicts ordering the persecution of Christians throughout the Roman Empire. Churches were destroyed, scriptures burned, and Christians were executed or forced to sacrifice to Roman gods. This was the last and most severe state-sponsored persecution.

Diocletian voluntarily abdicated the throne, retiring to his palace in Split (modern Croatia). He forced his co-emperor Maximian to do the same, setting a precedent for orderly succession, though the Tetrarchy soon collapsed after his departure.

Gallienus led Roman forces to victory against the Alemanni who had invaded Italy and reached Mediolanum (Milan). The victory secured northern Italy from Germanic incursions and demonstrated Gallienus's military capability during the Crisis of the Third Century.

After his father Valerian's capture, Gallienus reorganized the Roman army by creating a mobile cavalry force (vexillationes) under commanders like Aureolus. He also promoted equestrians over senators for military commands, reducing senatorial influence and improving military efficiency.

Gallienus issued an edict ending the persecution of Christians that had been enforced under his father Valerian. He restored Christian property and allowed freedom of worship, marking a shift in imperial policy toward Christianity before the later Edict of Milan.

Gallienus was murdered by his own officers while besieging the usurper Aureolus at Mediolanum. The conspiracy was led by Claudius, who succeeded him as emperor. Gallienus's death ended a 15-year reign that held the empire together during its deepest crisis.