User:Rupert Clayton/Persian gains of 363

The balance of power in the region shifted significantly in 363. The Roman emperor Julian mounted a campaign against Persia during the spring and summer of that year, taking his army down the Euphrates in a fleet of 1,000 boats. Despite defeating the Sassanid army at the Battle of Ctesiphon on 29 May, he was unable to take the city. Julian ordered the boats destroyed and pushed further east, perhaps with the aim of laying claim to more of Persia, or perhaps because he was expecting the arrival of 30,000 men under Procopius and Sebastianus, who had been sent via Armenia to approach down the east bank of the Tigris. However, Julian's army was harried by Sassanid forces, who also burned any crops in their path. Recognizing that they were far from their supply lines and at risk of attack by Shapur II's main army, the Romans decided on 16 June to retreat. Without boats to take them back up the Euphrates through Mesopotamia, it was decided to head north along the east bank of the Tigris and then through Corduene. The Persians continued to harry the retreating Romans. At the Battle of Maranga on 22 June, the Romans inflicted significant losses on the Persians and suffered few casualties themselves. However, the Roman army was getting dispirited and hungry. On 26 June, the Persians attacked the Roman rearguard at the Battle of Samarra. Julian rushed into battle, reportedly without armour, and was badly wounded. He died from his wounds shortly afterwards, although accounts vary as whether this was a few hours or three days later.

Following Julian's death, the general staff of the Roman army proclaimed Jovian his successor. Under Jovian's command, the army retreated to the Tigris, but was unable to cross. Facing annihilation of his army, Jovian accepted a humiliating treaty with Shapur. Under it Jovian surrendered the provinces of Arzanene, Moxoene, Zabdicene, Corduene and Rehimena to the Persians, including 15 castles, along with the cities of Singara and Nisibis, but not their inhabitants, and the fortress of Castra Maurorum. Before the treaty, Kepha had been on the border between Roman territory and the Roman-dominated Armenian kingdom of Arzanene.