At his death in 44 BC, Julius Caesar had been days away from leaving Rome to embark on a major military operation—the invasion of Parthia. Over the next 150 years, several emperors seized on the idea of realizing Caesar’s dream of conquering Parthia. In AD 66, Nero was marshaling his forces for an invasion of Parthia when the Jewish Revolt forced him to abort the plan and divert his legions to counter the revolt. With Nero’s death, the Parthian plan died too. It seems that Trajan had also long harbored the desire to become the conqueror of Parthia. Once he had brought Dacia into the Roman Empire and had consolidated the Dacian conquest, he was able to turn his full focus to the East.
Trajan was presented with an excuse to go to war with the Parthians. The current king of Armenia, Exedares, had been crowned by the Parthian king, Osroes, and had sworn loyalty to Parthia. Traditionally, the emperors of Rome had reserved the right to choose the kings of Armenia. But Trajan had another motive. According to Dio: “His real reason was a desire to win renown.” [LXVIII, 17]
In AD 113, Trajan gave orders for the legions of the East to prepare for a major campaign the following spring. He also ordered several of his European-based legions to transfer to Syria in preparation for the new campaign. He himself set off to sail to Syria via Greece accompanied by his wife, the empress Plotina, and elements of the Praetorian Guard and Singularian Horse. They traveled aboard ships of the Roman navy’s Misene Fleet from Misenum commanded by fleet prefect Quintus Marcius Turbo, who would later become prefect of the Praetorian Guard under Hadrian. [Starr, App., & Add.] A large part of the fleet remained in the East throughout Trajan’s eastern campaign. [Starr, viii]
One of the legions sent east for Trajan’s new campaign was the 1st Adiutrix. Founded in AD 68, it would have undergone a new enlistment over the winter of AD 108–109, so by AD 113 its numbers were up and its new recruits were settled and trained. The 1st Adiutrix marched west from Brigetio in Pannonia to the next legion base on the Danube, Carnuntum, and there its column was joined by the 15th Apollinaris Legion. Both legions then marched down to Ravenna in northeastern Italy to board warships of the Ravenna Fleet, which ferried them to Syria.
The 2nd Traiana Legion, raised by Trajan in AD 105 and sent to the East to support the annexation of Arabia Petraea, came up to Syria for the offensive from its base in Egypt. At the same time, the 3rd Cyrenaica at Bostra in Arabia Petraea prepared its weapons, ammunition and stores for a campaign the following year. In Cappadocia, just to the south of Armenia, the province’s governor Marcus Junius sent word to his two legions, the 12th Fulminata at Melitene and the 16th Flavia at Satala, to be ready to march in the spring.
Word soon reached the Parthian king that Trajan was heading to the East with an army, and immediately he saw himself as the Roman emperor’s target. By the time that Trajan reached Athens in Greece on his way east, Parthian envoys were awaiting him there. The envoys offered Trajan gifts and, telling him that Osroes had removed Exedares from the Armenian throne, sought a peace agreement. As part of the Parthian peace initiative, King Osroes asked that Trajan authorize him to make his nephew Parthamasiris the new king of Armenia. “The emperor neither accepted the gifts nor returned any answer, either oral or written,” said Dio, “except the statement that friendship is determined by deeds and not words, and that accordingly when he reached Syria he would do all that was proper.” [Dio, lxviii, 31]
Trajan’s nephew Hadrian had been a consul and governor of Lower Pannonia following the Dacian Wars, but his career had slowed dramatically after that. Hadrian had a great liking for Greek customs, and by AD 112 he was archon, or governor, of Athens, and was no doubt in the city when Trajan arrived there in AD 113 on his way to Syria. It seems that Trajan added Hadrian to his party at the urging of his wife Plotina, who was close to Hadrian, giving him the post of governor of Syria, for Dio wrote that Hadrian “had been assigned to Syria for the Parthian War.” [Dio, lxix, 1]
After Trajan’s fleets arrived at Laodicea, he and the imperial party spent the winter at Antioch. The facilities at Laodicea were apparently so overburdened by the influx of naval and military personnel that sailors and marines of the Misene Fleet were quartered at the long-deserted quarters of the 10th Fretensis Legion at nearby Cyrrhus. [Starr, Add.; and AE 1955, 225]
Trajan was joined at Antioch by his lieutenants for the campaign. Chief among these was the Moor Lusius Quietus. Quietus had served Trajan so loyally and effectively throughout the Dacian Wars that the emperor had, over the past seven years, made him a praetor, consul and provincial governor. Quietus was serving as governor of Judea when the emperor arrived in the East. Trajan’s other senior general, the trusted Lucius Appius Maximus, came out from Rome with him. Like Quietus, Maximus had served Trajan well in Dacia. Trajan no longer had the services of tough old Sura, the third of his successful Dacian War generals, who had died a natural death in around AD 108.
In the spring of AD 114, leaving his wife with Hadrian at Antioch, Trajan launched his eastern offensive; as governor of Syria, Hadrian had the task of ensuring that Trajan’s lines of supply were efficiently maintained. For the first stage of the campaign, Trajan marched his army north to Melitene in Cappadocia. As the army tramped along the Roman highways at a steady 18 miles a day, Trajan neither rode nor was carried in a litter; he marched on foot at the head of his troops, bareheaded. Each day, he personally decided the marching order. [Dio, lxviii, 23]
By the end of March, Trajan had reached Melitene and added the two Cappadocia-based legions to his column; from there, he swung east, crossing the Euphrates and entering Armenia. [Guey] The summer was still young when Trajan’s troops completed the seizure of southern Armenia, driving a wedge between the Armenians to the south and the forces in the north loyal to Parthamasiris, the nephew of Osroes, whom the Parthian king had proceeded to install on the Armenian throne.
When Marcus and his army reached the Armenian city of Elegeia, Parthamasiris left the rebuilt Armenian capital, Artaxata, and came to Trajan’s camp seeking an audience. Trajan was seated on a tribunal when the young Parthian prince approached, saluted him, and removed his crown and placed it at Trajan’s feet. Parthamasiris fully expected the Roman emperor to return his crown to him, just as Nero had returned that of Tiridates fifty years before. But Trajan did no such thing. Instead, he sent the prince and the Parthian members of his entourage away under Roman cavalry escort, and told the Armenians in the party to stay right where they were, as they were now his subjects. Soon, Trajan’s legions had brought all of Armenia under Roman control.
Trajan, after crossing the Tigris river and securing key frontier cities including Nisibis and Batnae, and leaving garrisons at strategic points, marched west to Edessa, modern Urfa in southeast Turkey. Situated on the plain of Haran, the city controlled a strategic hill pass to Mesopotamia and the Parthian heartland. At Edessa, Trajan received various eastern potentates before pushing south through the pass and occupying part of northern Mesopotamia. With the end of the year approaching, Trajan left the army camped in Parthian territory and returned to Syria to winter at Antioch. As he departed the army, he left orders for the legions to fell trees in the forests around Nisibis then use the wood to build collapsible boats for the new year’s campaign in Mesopotamia.
Over the winter, Antioch and many cities of the region were hit by a severe earthquake. The Syrian capital was badly damaged, and “multitudes” killed. [Dio, lxviii, 25] Among the casualties were foreign ambassadors waiting on the Roman emperor, and Marcus Vergilianus Pedo, who had just arrived in Syria after briefly serving as a consul in Rome and giving his name to the year. Trajan himself managed to escape with minor injuries, via a window of his quarters, being led from the ruins by men “of greater than human stature”; Dio was possibly referring to large Germans of the emperor’s Singularian Horse bodyguard. [Ibid.] For some days, Trajan lived in a tent in the Antioch chariot-racing stadium, the hippodrome, as aftershocks continued to shake the region.
The spring of AD 115 saw Trajan back with the army in Mesopotamia, and again on the advance. The six legions of the task force moved east through a landscape “destitute of trees.” A convoy of wagons had brought the newly constructed fleet of collapsible boats down from Nisibis, but as Trajan tried to send his troops across a river in his path—probably the Nighr—an opposition force that had assembled on the far bank made life difficult for the invaders by peppering them with missiles. [Ibid.]
This was the first mention in Cassius Dio’s narrative of the campaign of organized resistance in the field. It turned out that Trajan’s invasion had taken place at an opportune time, for “the Parthian power had been destroyed by civil conflicts and was still at this time the subject of strife.” [Dio, LXVIII, 22] The Parthians were locked in a civil war. It is likely that the troops who opposed Trajan at this river crossing comprised the small army of the kingdom of Adiabene, a Parthian ally in northern Mesopotamia.
After assembling their vessels, Trajan’s legions began to build a bridge of moored boats across the river. In the usual Roman textbook fashion, there were several craft at the forefront of this growing bridge, equipped with towers and screens, and manned by archers and heavy infantry with javelins who rained missiles down on the enemy. At the same time, various Roman units dashed this way and that, up and down the western bank of the river, giving the impression that they were going to cross in boats at various points. This forced the outnumbered enemy to divert detachments from their army to hurry up and down the bank in order to be in position to counter these crossings. With the main enemy defense weakened, Trajan was able to send his troops across the bridge of boats in force.
There was a brief battle on the eastern side of the river, but Trajan had overwhelming numbers—his army would have comprised 60,000–70,000 fighting men at the commencement of the offensive the previous year. “The barbarians gave way,” said Dio. [Dio, LXVIII, 21] Once across the river, the Roman army quickly gained possession of the kingdom of Adiabene.
To Trajan, this was a special moment. Like so many Roman generals including Julius Caesar, Trajan had a desire to emulate the deeds of Alexander the Great. Alexander had brought his army here to Adiabene. [Ibid.] And it was here, on the plain in the vicinity of the ancient cities of Nineveh, Arbela and Gaugamela, that the Macedonian army had defeated King Darius’ Persian army in 331 BC.
Further to the south, at Adenystrae, modern-day Irbil, 70 miles (112 kilometers) north of Kirkuk in today’s northern Iraq, there was a strong Parthian fort. When Trajan sent a legion centurion named Sentius ahead to give the Adenystrae garrison a chance to surrender, the Parthian commander, Mebarsapes, rejected the offer and imprisoned the centurion. In the Adenystrae dungeon, Sentius convinced other prisoners to help him. The centurion duly escaped, found Mebarsapes, then killed him, and opened the fort gate as the Roman army approached. Centurion Sentius’ rewards from a grateful Trajan can only be imagined.
As the Roman army continued its advance down the Euphrates, “quite free from molestation” from the enemy and apparently using the collapsible boats to transport its supplies, Trajan conceived the idea of building a canal between the Euphrates and the Tigris. [Dio, LXVIII, 26, 28] This was to allow him to follow the Tigris all the way to the Persian Gulf, or the Erythreaean Sea as the Romans called it. The courses of the two rivers come tantalizingly close near where the later city of Baghdad would rise, but Trajan’s engineers warned him that his canal was not practical because the Euphrates flowed at a higher elevation than the Tigris, and a canal would only run the Euphrates dry. The determined emperor therefore had his troops drag the boats overland to the Tigris.
On the eastern bank of the Tigris, the legions came to Parthia’s winter capital, Ctesiphon. Its Parthian defenders put up some resistance, but the legions soon captured it, and, apparently, also captured neighboring Seleucia. At an assembly in Ctesiphon, Trajan was hailed imperator by the legions. It seems that Trajan and the bulk of his army spent the winter of AD 115–116 there at Ctesiphon, with Trajan occupying the palace of the kings of Parthia. From there, Trajan sent his latest dispatches to the Senate at Rome. Following the AD 114 campaign, the Senate had granted Trajan the title Optimus, meaning “Most Excellent.” When news of the emperor’s latest successes in the East arrived, especially the taking of the Parthian capital, the Senate granted him the additional title of “Parthicus.”