Gallienus was a Roman emperor who ruled from 253 to 268 CE, first with his father Valerian and then alone after his father’s capture by the Persians. He faced many challenges during his reign, such as foreign invasions, civil wars, and economic crises. He also introduced some reforms that changed the structure and culture of the Roman Empire.

Gallienus was born around 218 CE into a wealthy and influential senatorial family. His father was Valerian, a successful general and politician who became emperor in 253 CE after the assassination of Aemilianus. Valerian appointed his son as co-emperor and gave him the responsibility of defending the western provinces, while he himself focused on the eastern frontiers. Gallienus proved to be a capable military leader, defeating several usurpers and barbarian tribes that threatened the stability of the empire.

However, in 260 CE, Valerian was captured by Shapur I, the king of the Sasanian Empire, during a campaign in Mesopotamia. This was a humiliating blow for Rome and a major crisis for Gallienus, who now had to deal with the entire empire on his own. He also had to face several rebellions from rival claimants to the throne, such as Postumus in Gaul, Macrianus in Syria, and Odaenathus in Palmyra. Gallienus managed to suppress some of these revolts, but he also had to tolerate the existence of independent or semi-independent states within the empire.

Gallienus also tried to reform the administration and the army of the empire, in order to cope with the challenges of his time. He transferred the command of the legions from the senators to the equestrians, creating a new class of professional officers loyal to him. He also created a mobile cavalry force that could respond quickly to any threat. He promoted religious tolerance and patronized arts and sciences, especially Neoplatonism. He issued coins with new designs and slogans that reflected his ideology and propaganda.

Gallienus’ reign was marked by both successes and failures, but he showed resilience and innovation in a time of crisis. He was assassinated in 268 CE by a conspiracy of his own officers, who were unhappy with his policies and his leniency towards some of his enemies. He was succeeded by Claudius II, one of his generals. Gallienus’ legacy is mixed: he is often criticized for losing control of large parts of the empire, but he is also praised for his reforms and his cultural achievements.