Valerian (P. Licinius Valerianus) (r. 253–260), born before 200 A.D., married Egnatia Mariniana and had two sons, Gallienus
(born c. 218) and a junior Valerian. Gordian sent Valerian, as an ex-consul, to Rome, in 238, to elicit senatorial approval of Gordian's replacement of Maximinus Thrax as emperor. [Gordian became Emperor Gordian I
.] In 253, Emperor Gallus
asked Valerian to bring troops to help in the fight against Aemilianus, but before this could happen, Gallus' troops killed him and his son and joined up with Aemilianus. Valerian's men appointed their leader emperor and marched against Aemilianus. At this point, Aemilianus' fickle men killed Aemilianus, too, and transferred allegiance to Valerian. They supported his claim as Emperor Valerian I. The Roman Senate approved Valerian as emperor and made his son P. Licinius Egnatius Gallienus co-emperor, assigning the West to the son and the East to Emperor Valerian I. In 257, Valerian freed Antioch, Syria, from Persian control. Valerian tried to negotiate a peace treaty with the Persian king Sapor
(www.allbiographies.com/biography-ShapurorSaporII-29056.html: 309-379), but was captured, humiliated, and eventually skinned by the Persian king. It wasn't until the Tetrarchy that the Romans obtained revenge. [See Han Holbein's rendering of Valerian's humiliation.
Eusebius (c. 275-339) says Valerian persecuted the Christians.
Source: Valerian (A.D. 253-260) and Gallienus (A.D. 253-268)