After a bloody stalemate in the second battle of Edessa, King of kings Shapurmax I withdrew his demoralised army to Persia, avoiding a close pursuit by the roman army and leaving back all his baggage train.
The satraps were unhappy about his leadership, and the royal army had suffered heavy losses. Shapurmax knew he needed to reorganize the army and reassert his leadership. He decided to sent a peace offer to the Romans, with Duca Topo as hostage. He planned to gather allies and launch a new offensive the year after, in 263AD. Maybe the Romans, having regained all the lost areas could be idle and be caught off guard. Emperor Peronianus was glad of this truce: he had the time to go back to Rome and be ready the following year to launch an offensive against Persia. So both the leaders accepted a fake peace, building up new armies to smash each other.
Shapurmax was able to gain back the support from Loritzvad II, the Armenian King. This was dealing with the Romans, afraid of the presence of Shun Merrat in the Sassanid army. Shapurmax sent to the Armenian king the armenian rebel head, and renewed the alliance with the puppet king.
Peronianus was the faster to launch the offensive in 263AD: he appeared in front of the fortified city of Nisibis, forcing the King of kings to hastily mobilize his army to save this important fortress.
The battle of Nisibis was going to start
This battle ended the war. Shapurmax I had to beg for the peace, and gave to the Romans lands and cities to obtain it. His throne was at risk, and a portion of his kingdom was the price paid to the Romans to focus on the internal trouble. Peronianus earned his triumph and the name "Parthicus", having smithed the dangerous foe, but a new generation of kings and warriors will grow....