Following the defeat of his rival Licinius in AD324, the Emperor Constantine has reigned for twelve years over a united Roman world. Under his patronage, Christianity continues to gain in strength and influence, while followers of the older religions increasingly feel that the traditional ways of Rome are dying away.
But the emperor himself is getting old, and facing new challenges. In the east, Shapur II, the young and vigorous King of Persia, disputes Constantine's claim of protection over the Christians living within his domains. In Armenia, a state allied to Rome, the king has converted to the new faith, adding fuel to the simmering fires of Persian resentment.
Now, as Constantine reaches the thirtieth anniversary of his rule, the ancestral enmity between the two great powers threatens once again to break into open war.