253 Proclaimed emperor; marches on Rome; recognized by the Senate after the death of Aemilianus; Sasanian invasion of Syria; Gothic naval expedition to Asia Minor; appoints Gallienus co-ruler
254 Consul II (with Gallienus); Sasanian king Shapur takes Nisibis; the Goths enter Thrace and Thessaly but are defeated at Thermopylae; the Marcomans invade Pannonia and cross the Alps; they reach Ravenna but are repelled; Valerian accepts title Germanicus maximus; moves to the east to wage war against the Sasanian empire; liberates Antioch; end of usurpation of Uranius Antoninus in Emesa
255 Consul III (with Gallienus II); continued war in the east
256 Naval expedition by the Visigoths to Asia Minor; Valerian returns to the west (to Rome?); Sasanians sack Dura Europos
257 Consul IV (with Gallienus III); start of persecution of the Christians
