The second Romano-Persian war
It's the year 305AD. Much time is passed by the disastrous war waged by Shapurmax I against Rome. A war that costed dearly to the persian, forced to sue peace and cede many lands and cities to the hated romans. Two generation later Shapurmax III is ready to strike, to revenge the sassanid, and to seize his land, grabbed by Rome.
With a large army he advanced along the Euphrates river to strike at Dura Europos and break the roman defensive system. The roman had not been idle tough. The Emperor Sardinicus has been warned of the persian preparations, and was ready to stop the enemy thrust.
The two armies met near the city if Dura Europos, both willing to destroy the enemy
So it ends the second persian offensive. The army is destroyed, the country is in disarray and near civil war. It is time for a new dynasty to take the throne. Shapurmax has failed, but new warriors will come and confront Rome mighty.