The Battle Of Ctesiphon: Emperor Julian’s Lost Victory

In the Spring of 363 CE, a large Roman army left Antioch. It was the beginning of the ambitious Persian campaign led by emperor Julian, who wanted to fulfill a centuries-old Roman dream – to defeat and humiliate its Persian nemesis. More importantly, the victory in the East could bring Julian immense prestige and glory, something that eluded so many of his predecessors who dared to invade Persia. Julian held all the winning cards. At the emperor’s command was a large and powerful army led by veteran officers. Julian’s ally, the Kingdom of Armenia, threatened the Sassanids from the North. Meanwhile, his enemy, the Sassanid ruler Shapur II was still recovering from a recent war. Julian capitalized on those conditions early in the campaign, rapidly moving deep into Sassanid territory, encountering relatively little opposition. However, the emperor’s hubris and his eagerness to achieve a decisive victory led Julian into a self-made trap. At the Battle of Ctesiphon, the Roman army defeated the superior Persian force.

Yet, unable to take the enemy’s capital, Julian had no other option but to retreat, taking a path that led the emperor to his doom. In the end, instead of a glorious victory, Julian’s Persian campaign ended in an ignominious defeat, the emperor’s death, the loss of Roman lives, prestige, and territory.

In early March 363 CE, a large Roman force left Antioch and embarked on the Persian campaign. It was Julian’s third year as the Roman Emperor, and he was eager to prove himself. A scion of the famous Constantinian dynasty, Julian was not a novice in political affairs. Nor was he an amateur in military matters. Before ascending the throne, Julian had proven himself fighting the barbarians at the Rhenian limes. His magnificent victories in Gaul, like the one at Argentoratum (present-day Strasbourg) in 357, brought him favor and devotion of his troops, as well as the jealousy of his relative, emperor Constantius II. When Constantius called for the Gallic army to join his Persian campaign, the soldiers revolted, proclaiming their commander, Julian, the emperor. Constantius’ sudden death in 360 spared the Roman Empire from a civil war, leaving Julian its sole ruler. 

Julian, however, inherited a deeply divided army. Despite his victories in the West, the eastern legions and their commanders were still loyal to the late emperor. This dangerous division within the imperial army could play a role in Julian making the decision, which would take him to Ctesiphon. Three decades before Julian’s Persian campaign, another emperor, Galerius, scored a decisive victory over the Sassanids, taking Ctesiphon. The battle brought the Romans into a superior position, expanding the Empire eastwards, while Galerius reaped military glory. If Julian could have emulated Galerius and win a decisive battle in the East, he would have received that much-needed prestige and strengthened his legitimacy.  

The triumph in the East could also help Julian pacify his subjects. In the rapidly Christianizing Empire, the emperor was a staunch pagan known as Julian the Apostate. While wintering in Antioch, Julian came in conflict with the local Christian community. After the famous temple of Apollo at Daphne (reopened by Julian) burned in flames, the emperor blamed the local Christians and closed their main church. The emperor did not make an enemy only of the Christians but of the entire city. He mismanaged resources in times of an economic crisis and attempted to impose his own ascetic morality upon a populace known for its love of luxury. Julian (who sported a philosopher beard), recorded his dislike of the citizens in the satirical essay Misopogon (The Beard Haters). 

When the emperor and his army left Antioch, Julian probably let out a sigh of relief. Little did he know that he would never see the hated city again.

Besides the emperor’s pursuit of glory and prestige, more practical benefits could be achieved by defeating the Sassanids on their home turf. Julian hoped to stop Persian raids, stabilize the eastern frontier, and perhaps get further territorial concessions from his problematic neighbors. More importantly, a decisive victory could provide an opportunity for him to install his own candidate on the Sassanid throne. Accompanying the Roman army was Hormisdas, the exiled brother of Shapur II. 

After Carrhae, where centuries earlier the Roman commander Crassus had lost his life, Julian’s army split into two. A smaller force (numbering c. 16,000 – 30,000) moved towards Tigris, planning to join the Armenian troops under Arsaces for a diversionary attack from the North. The main army (c. 60,000) led by Julian himself advanced southwards along the Euphrates, towards the main prize – Sassanid’s capital Ctesiphon. At Callinicum, an important fort on the lower Euphrates, Julian’s army met with a large fleet. According to Ammianus Marcellinus, the river flotilla contained over a thousand supply ships and fifty war galleys. In addition, special vessels were built to serve as pontoon bridges. Passing the border fort of Circesium, the last Roman place Julian would ever set his eyes on, the army entered Persia.

The Persian campaign opened with an ancient blitzkrieg. Julian’s choice of routes, the army’s rapid movements, and the use of deception allowed the Romans to advance into the enemy territory with relatively little opposition. In the weeks that followed, the imperial army took several major towns, ravaging the surrounding area. The garrison of the island town of Anatha surrendered and was spared, though the Romans burned the place. Pirisabora, the largest city of Mesopotamia after Ctesiphon, opened its gates after two or three days of siege, and was destroyed. The fall of the citadel allowed Julian to restore the Royal Canal, transferring the fleet from the Euphrates to the Tigris. As the Persians flooded the area to slow the Roman advance, the army had to rely on pontoon bridges. On their way, the imperial legions besieged and took the fortified city of Maiozomalcha, the last bastion standing before Ctesiphon.

By now, it was already May, and it was getting unbearably hot. Julian’s campaign was proceeding smoothly, but he had to act quickly if he wanted to avoid a protracted war in the sweltering heat of Mesopotamia. Thus, Julian decided to strike directly at Ctesiphon. The fall of the Sassanid capital, the emperor believed, would force Shapur to beg for peace. 

Approaching Ctesiphon, the Roman army seized Shapur’s lavish royal hunting grounds. This was a lush, green land, filled with all sorts of exotic plants and animals. The place was once known as Seleucia, a great city founded by Seleucus, one of Alexander the Great’s generals. In the fourth century, the place was known as Coche, the Sassanid capital’s Greek-speaking suburb. Although Persian attacks increased, exposing Julian’s supply train to hostile raids, there was no sign of Shapur’s main army. A large Persian force was sighted outside Maiozamalcha, but it quickly withdrew. Julian and his generals were getting nervous. Was Shapur reluctant to engage them? Was the Roman army being led into a trap?

The uncertainty gnawing at the emperor’s mind increased when he reached his long-sought prize. The large canal that protected Ctesiphon had been dammed and drained. The deep and swift Tigris presented a formidable obstacle to cross. Besides that, Ctesiphon had a substantial garrison. Before the Romans could reach its walls, they had to defeat the defending army. Thousands of spearmen, and more importantly, the vaunted mail-clad cavalry – the clibanarii – barred the way. It is unclear how many soldiers defended the city, but to Ammianus, our primary source and eyewitness, they were an impressive sight.

Undeterred, Julian began preparations. Here with the battle at Ctesiphon, he had thought, he could bring the campaign to a close and return to Rome as the new Alexander. After refilling the canal, the emperor ordered a daring night attack, sending several ships to establish a foothold on the other shore of the Tigris. The Persians, who controlled the high ground, offered stiff resistance, showering the legionaries with flaming arrows. At the same time, the artillery hurled clay jugs full of naphtha (flammable oil) on the ships’ wooden decks. Although the initial attack did not go well, more ships crossed. After intense fighting, the Romans secured the beach and pressed forward.

The Battle of Ctesiphon unfolded on a broad plain in front of the city walls. Surena, the Sassanid commander, arrayed his troops in a typical fashion. Heavy infantry stood in the middle, with light and heavy cavalry protecting the flanks. The Persians also had several mighty war elephants, which undoubtedly left an impression on the Romans. The Roman army was composed chiefly of heavy infantry and smaller elite mounted detachments, while the Saracen allies provided them with light cavalry. 

Ammianus, sadly, does not offer a detailed account of the battle of Ctesiphon. The Romans opened the battle hurling their javelins, while the Persians responded with their signature hail of arrows from both mounted and foot archers to soften the enemy’s center. What followed was an attack of the vaunted heavy cavalry – mail-clad clibanarii – whose terrifying charge often caused the opponent to break lines and flee before the horsemen reached them.

We know, however, that the Sassanid attack failed, as the Roman army, well prepared and of good morale, offered strong resistance. The emperor Julian also played a significant role, riding through the friendly lines, reinforcing weak points, praising brave soldiers, and castigating the fearful. The threat of the mighty clibanarii, armored from head to toe (including their horses), was lessened by sweltering heat. Once the Persian cavalry and elephants were driven from the battlefield, the entire enemy line buckled, giving way to the Romans. The Persians retreated behind the city gates. The Romans won the day.

According to Ammianus, more than two thousand Persians perished in the battle of Ctesiphon, compared to only seventy Romans. Although Julian won the battle of Ctesiphon, his gamble failed. What followed was a heated debate between Julian and his staff. The Roman army was in good condition, but it lacked the siege equipment to take Ctesiphon. Even if they surmounted the walls, the legionaries had to fight the city’s garrison, bolstered by those who survived the battle. Most distressing, Shapur’s army, far larger than the one just defeated, was closing in quickly. Following failed sacrifices, seen by some as a bad omen, Julian made his fateful decision. After ordering all the ships to be burned, the Roman army started the long journey through the interior of the hostile territory. 

For centuries, historians tried to make sense of Julian’s reasoning following the battle of Ctesiphon. The destruction of the ships freed additional men (who joined the main army) while denying the Persians the use of the fleet. Yet, it also deprived the Romans of a vital route in the case of a retreat. A venture deep into the interior could resupply the massive army and provided ample opportunity for foraging. But it also allowed the Persians to deny those vital supplies adopting a scorched earth policy. Julian, perhaps, hoped to meet with his Armenian allies and the rest of his troops and force Shapur into combat. Failing to take Ctesiphon, defeating the Sassanid ruler could still cause the enemy to sue for peace. But this never came to be. 

The Roman retreat was slow and arduous. The stifling heat, lack of supplies, and increasing Sassanid raids, gradually weakened the legions’ strength and lowered their morale. Near Maranga, Julian was able to repel the first significant Sassanid attack, winning an indecisive victory. But the enemy was far from defeated. The final blow came swiftly and suddenly, few days after the Romans left Ctesiphon. On 26th June 363, near Samarra, the heavy Persian cavalry surprised the Roman rearguard. Unarmored, Julian personally joined the fray, encouraging his men to hold the ground. Despite their weakened condition, the Romans performed well. However, in the chaos of battle, Julian was struck by a spear. By midnight, the emperor was dead. It is unclear who killed Julian. Accounts contradict each other, pointing to a disgruntled Christian soldier or an enemy cavalryman. 

Whatever transpired, Julian’s death signaled the ignominious end of a promising campaign. Shapur allowed the defeated and leaderless Romans to retreat to the safety of the imperial territory. In return, the new emperor, Jovian, had to agree to harsh peace terms. The Empire lost most of its eastern provinces. Rome’s influence in Mesopotamia was wiped out. Key fortresses were handed to the Sassanids, while Armenia, a Roman ally, lost the Roman protection. 

The Battle of Ctesiphon was a tactical victory for the Romans, the highpoint of the campaign. It was also the victory lost, the beginning of an end. Instead of glory, Julian got a tomb, while the Roman Empire lost both the prestige and the territory. Rome did not mount another major invasion in the East for nearly three centuries. And when it finally did, Ctesiphon remained out of its reach.