Julian’s Invasion of Persia (363)

In the spring of 363 CE the Roman emperor Julian invaded the Sasanian Empire with one of the largest armies Rome ever sent east. He fought his way down the Euphrates to the walls of Ctesiphon and won a battle outside the city, but could not take it. During the retreat he was mortally wounded, and his successor Jovian had to accept a peace with Shapur II that handed Nisibis and five frontier regions to Iran.

Why Julian invaded

Julian, the last pagan emperor of Rome, inherited a war that had dragged on since 337. Shapur II had taken Amida, Singara and Bezabde in 359–360 (see Shapur II), and Julian’s cousin Constantius II had died before he could respond. Julian wanted a decisive victory, both to secure the frontier and to win the prestige he needed for his religious programme at home. Ancient writers also compared him to Alexander the Great, and he may have seen himself in that light.

He rejected a Persian offer to negotiate. His most reliable historian, Ammianus Marcellinus, a soldier who marched with the army and later wrote Books 23 to 25 of his history about the campaign, admired Julian but did not hide his mistakes.

The march down the Euphrates

Julian left Antioch on 5 March 363. At Carrhae he divided his forces. A northern army under his relative Procopius and the general Sebastianus was to join the Armenian king Arshak II and advance down the Tigris. Julian led the main army, with a large river fleet carrying supplies, down the Euphrates.

The army moved fast. Fortresses along the river surrendered or were stormed: Anatha gave up without a fight, Pirisabora was captured and burned, and Maiozamalcha, near Ctesiphon, was taken after a siege in which Roman soldiers tunnelled under the walls. Persian forces flooded fields by breaking the irrigation dykes and harried the column, but did not risk a full battle. To reach the Tigris, the Romans reopened an old canal, the Naarmalcha, and brought the fleet across.

The battle before Ctesiphon

At the end of May, Julian forced a crossing of the Tigris at night and attacked the Persian army drawn up on the east bank in front of Ctesiphon. The Persians fielded armoured cavalry and elephants, but the Roman infantry broke them, and the survivors fled behind the city walls. Ammianus reports Persian losses of about 2,500 against some 70 Romans, figures that probably flatter the Romans.

It was a victory, but not the one Julian needed. Ctesiphon was strongly fortified, the Roman siege train was inadequate, and Shapur’s main army was approaching. The northern force under Procopius never arrived. After a council of war, Julian decided not to besiege the city.

The burning of the fleet and the retreat

Julian then made the most criticised decision of the campaign: he burned most of his fleet, which could not be dragged back up the river and might fall into Persian hands, and marched inland, apparently hoping to meet his northern army or to draw Shapur into battle. Persian guides, whom some sources describe as deliberate deceivers, led the army into burned and flooded country. The Persians destroyed crops ahead of the Romans and attacked their flanks and rear without offering a pitched battle. Food ran short, and the army turned north along the Tigris towards Roman territory.

The death of Julian

On 26 June 363, near Samarra, the rearguard came under sudden attack. Julian rushed into the fight without his breastplate. A cavalry spear struck him in the side and pierced his liver. He was carried to his tent, where, according to Ammianus, he spent his last hours discussing the soul with his philosophers. He died that night, aged 31 or 32.

Who threw the spear

Nobody knew who struck the blow. Ammianus is uncertain. Julian’s friend Libanius later claimed the killer was a Christian in Julian’s own army, angered by the emperor’s attempt to revive paganism. Other sources name a Saracen (Arab) auxiliary fighting for Persia, or a Persian horseman. Christian writers made the death a miracle: a later legend says the soldier-saint Mercurius killed him at God’s command, and an often-repeated but late story puts the words “You have won, Galilean” in Julian’s mouth. Historians regard both as legends.

Jovian’s treaty

The next morning the officers chose Jovian, the commander of the imperial guard, as emperor. The army was hungry, far from home and on the wrong side of the Tigris, with Shapur’s forces all around. Shapur offered terms, and Jovian accepted them within days:

• A peace for thirty years.
• Rome returned to Persia the five regions beyond the Tigris gained in 299 (Ammianus names Arzanene, Moxoene, Zabdicene, Rehimene and Corduene), with fifteen fortresses.
• Rome handed over Nisibis, Singara and the fort of Castra Maurorum.
• Rome would no longer support the king of Armenia against Persia.

The inhabitants of Nisibis were allowed to leave and most moved west into Roman territory. Among them was the poet and theologian Ephrem the Syrian, who settled in Edessa. Ammianus calls the treaty shameful, and Roman writers blamed Jovian for it for generations. Modern historians are kinder: with the army facing starvation, Jovian may have had little choice.

Remembering the victory

For the Sasanians, 363 undid the defeat of Narseh (see Narseh and the Peace of Nisibis) and confirmed Shapur II as the greatest king of his line. At Taq-e Bostan near Kermanshah, a relief of his successor Ardashir II shows the king and Ahura Mazda standing over a fallen enemy. Many scholars identify the fallen man as Julian, although this is not certain. The frontier set in 363 lasted, with small changes, until the great war of the seventh century. For the wider pattern, see Persia and Rome: Seven Centuries of Rivalry, and for the city Julian failed to take, Ctesiphon: Capital of Two Empires.

1. 5 March 363 Julian leaves Antioch
2. April–May 363 March down the Euphrates; Pirisabora and Maiozamalcha taken
3. Late May 363 Battle before Ctesiphon; decision not to besiege
4. June 363 Fleet burned; retreat north along the Tigris
5. 26 June 363 Julian mortally wounded near Samarra
6. 27 June 363 Jovian proclaimed emperor
7. July 363 Treaty with Shapur II