Battle of Ctesiphon (363)

At the end of May 363, the Roman emperor Julian brought his invading army to the walls of Ctesiphon, the Sasanian capital on the Tigris in what is now Iraq, and on 29 May defeated a Persian force drawn up in front of the city. The victory won him nothing lasting. Unable to take the fortified capital and far from his supplies, Julian turned away, and within a month he was dead and his army was forced into a humiliating peace.

Julian became sole ruler of the Roman Empire when his cousin Constantius II died on 3 November 361. The most pressing danger in the east was the Persian king Shapur II, whose forces had taken the frontier fortress of Amida in 359. Julian rejected Persian approaches for talks and spent more than a year preparing a large offensive. From his forward base at Antioch he set out on 5 March 363. Estimates of his army vary, from about 65,000 to 90,000 men.

The plan was a pincer. A detachment of some 18,000 under his relative Procopius was sent north to work with Rome's ally, the king of Armenia, while Julian took the main army and a river fleet down the Euphrates. Shapur's main army was not at Ctesiphon when the advance began, and the Persians fell back on a scorched-earth policy, burning crops and supplies in the invaders' path.

Julian's fleet passed from the Euphrates into the Tigris through a canal his men cleared, and the army was ferried across to face the defenders on the eastern bank. The Persian army there, commanded by Merena, included armoured cavalry, close-packed infantry and war elephants according to the Roman historian Ammianus Marcellinus. The Romans crossed at night, achieved surprise, and then fought a long struggle on the river bank, said to have lasted twelve hours. The Persians were driven back inside the walls.

The losses recorded in the ancient accounts are lopsided: about 2,500 Persian dead against no more than 70 Romans. The Christian church historian Socrates Scholasticus, no admirer of the pagan Julian, even claims that Shapur now offered him a large part of his kingdom to withdraw.

Victory in the field did not open the gates. Ctesiphon was strongly fortified, Julian lacked the means for a long siege, Procopius's northern army never appeared, and Shapur's main force was believed to be approaching. A council of war decided not to besiege the city. Julian then burned most of his fleet and its stores so that they would not fall to the enemy, a decision criticised by ancient and modern writers alike, and marched inland. Hunger, heat and disease weakened the army, and on 16 June the retreat began.

Harassed all the way by Persian forces, the Romans fought at Maranga and then near Samarra, where Julian, rushing into the fight without his armour, was struck by a spear. He died on 26 June 363. His officers chose Jovian, a guards officer, as emperor. Trapped and short of food, Jovian accepted Shapur's terms: Rome gave up Nisibis, Singara and a group of provinces east of the Tigris, abandoned its ally Armenia and agreed to a 30-year truce. The campaign that began with a triumph outside Ctesiphon ended with major territorial losses to the Sasanian Empire.

Our 300 map shows Rome and Sasanian Persia facing each other across upper Mesopotamia, and the 400 map shows the frontier after the cessions of 363, in the lands of today's Iraq and south-eastern Turkey.