In the Battle of Magnesia (190 BC), the Romans destroyed the army of the Seleucid Empire, which was founded in 312 BC by Seleucus I Nicator, the General of Alexander the Great, and brought Seleucid hegemony in Asia Minor to an end. But by defeating the Seleucid Empire, the Romans created space for the rise of a nomadic tribe that would one day stop their advance in the East: the Parthians, who were an offshoot of the Scythians.
Between 247 and 190 BC, the Parthians were administering the far-flung areas of the Seleucid Empire. They saw themselves as the vassals of the Seleucid Emperor. When the Seleucid Empire fell into disarray, after their defeat by the Romans, the Parthians decided that the time to upgrade their status from vassals to independent kings had finally arrived. The Parthians started fighting for the control of the Seleucid territory from Afghanistan to the Middle East. For the next 400 years, they would fight wars and rule their vast territory on horseback.
In 140 BC, Parthian King Mithradates I decisively defeated and captured the Seleucid King Demetrius II. After that Mithradates defeated the Greek kings of Bactria. This gave the Parthians control of the eastern half of the Seleucid Empire, including the city of Babylon, then the most prosperous city in Europe and Middle East. This was a stunning achievement for people who were steppe nomads and barbarians.
As the Parthian Empire continued to expand, it reached the border of the Kingdom of Armenia which was on Rome’s radar. In 69 BC, Roman general Lucius Licinius Lucullus defeated the army led by King Tigranes the Great of the Kingdom of Armenia in the Battle of Tigranocerta. With this victory, Rome became a military power in the Middle East. Now Roman power extended up to the Euphrates.
In his essay, "The Life of Lucullus,” Plutarch says that on October 6, when the Roman army stood facing the Armenian army at the Batman-Su river, a tributary of Tigris, the Roman soldiers implored General Lucullus that he should delay the fighting. They believed that October 6 was unlucky for the Romans since this was the day of the disastrous Battle of Arausio in which the Roman army was decisively defeated by the Germanic tribes of Cimbri and Teuton.
Lucullus would not be swayed. He was adamant that the battle would go ahead on October 6. According to Plutarch, Lucullus told his soldiers: "Verily, I will make this day, too, a lucky one for the Romans.” He realized that the heavily armored cavalry (the cataphracts) were the major threat that his men faced. He led a part of his troops downriver, towards an area where the river was easy to ford.
The motion of the Roman army was interpreted by King Tigranes as a sign that Lucullus was not keen on fighting the battle and that he was trying to evacuate his Roman army by fording the river.
To divert the attention of the cataphracts, Lucullus ordered his Gallic and Thracian cavalry to launch an attack. Meanwhile, the troops that he had led downriver crossed over to the river’s other side and, after circling a hill, they attacked the Armenian army from the behind. Plutarch writes that Lucullus himself led the charge on foot. He reached the top of the hill and said to his soldiers: “The day is ours, the day is ours, my fellow soldiers!”
The Armenian cataphracts, being heavily armored, could not be swiftly maneuvered. When the Romans advanced from two sides, the cataphracts started crashing into the formations of their own army. The Armenian line was broken at several points. Tigranes was forced to flee to save his life. In his book The Art of War, Niccolò Machiavelli has criticized Tigranes for relying heavily on armored cavalry and ignoring his infantry.
The Roman victory over the Kingdom of Armenia made a conflict between Rome and the Parthian Empire inevitable. In 53 BC, Marcus Licinius Crassus, Roman General and Statesman, decided to attack the Parthian Empire primarily because he desired to match the military victories of his two major rivals, Pompey the Great and Julius Caesar. Ovid, the Roman poet who lived in the time of Augustus, has written that the battle between the legions of Crassus and the Parthian forces happened on 9 June near the town of Carrhae (present-day Harran, Turkey).
The Parthian king Orodes II sent his general called Surena with a cavalry force to fight the legions of Crassus. According to Plutarch, Surena had 10,000 soldiers while Crassus had over 50,000 soldiers. But Surena’s heavily outnumbered forces managed to inflict severe casualties on the Romans. In one of the engagements, a detachment of 2000 Roman soldiers led by Publius, the son of Crassus was decimated by the Parthians. The Parthians decapitated Publius and paraded his head on top of a spear in front of the Roman lines.
Crassus was devastated by the sight of his son’s head on a Parthian spear. Demoralization and panic had set into the Roman legions. They were not in a position to stand against the highly mobile Parthian horsemen. Surena invited Crassus to a peace summit. He offered a truce and the chance for the Romans to withdraw to Syria in exchange for Roman territory east of Euphrates.
Since they had killed his son, Crassus was not willing to negotiate with the Parthians. But his soldiers were furious with him for leading them into a disastrous battle. They threatened to mutiny if he did not go to the peace summit. At the summit, a Parthian soldier pulled the reins of Crassus’s horse. In the fighting that followed, Crassus and the Roman Generals who had accompanied him were killed. After that the Parthians killed many Roman legionaries and took the rest prisoner. Since Crassus was known as the “richest man in Rome,” the Parthians poured molten gold in the throat of his dead body to mock his lust for gold.
This was a humiliating defeat for Rome. The Romans wanted vengeance. But when Augustus became the Emperor in 27 BC, he transformed the Roman policy towards the Parthians. He preferred to negotiate rather than to invade. Through diplomatic initiatives, he was able to recover the Roman captives that the Parthians had from the Battle of Carrhae.