AR22 - Valerian and Gallienus L Δ

This tetradrachm was struck in Year 4 of the joint reign, when Valerian and Gallienus were still nominally co-emperors with some functional coherence between them — a situation that would deteriorate sharply. Within two years, Valerian was campaigning against Shapur I and would become the only Roman emperor captured alive in battle, at Edessa in 260. The Alexandria mint continued producing in Gallienus's name alone after that disaster, making joint-reign issues like this one a narrow chronological window.