He rose as pretender to the throne against his grand-nephew Bahram III in 293, and soon became sole King. He attacked the Romans, but after defeating the Emperor Galerius (305311) near Callinicum on the Euphrates in 296 was completely defeated in 297, and forced to conclude a peace, by which western Mesopotamia and five provinces on the left bank of the upper Tigris were ceded to the Romans and their sovereignty over the kingdom of Armenia was acknowledged.
This peace, concluded in 297, lasted for forty years, until 337. Narses died in 302 and was succeeded by his son Hormizd II (302309).
