Palmyrene Empire
The Sassanid Empire was a major threat to the Roman power in the East. King Shapur I conquered the base of the XV "Apollinaris", Satala (256), and sacked Trapezus (258). Emperor Valerian moved against Shapur, but was defeated and captured. The defeat caused the partial collapse of the Empire, with the secessionistic Gallic Empire in the West and Palmyrene Empire in the East. It is known that the XII "Fulminata" was under the command of Odaenathus, ruler of the Palmyrene Empire, but also that Emperor Gallienus awarded the legion with the cognomen "Galliena".