How the Romans Defeated the Seleucid Empire at Magnesia | History Hit

How the Romans Defeated the Seleucid Empire at Magnesia

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In 190 BC, the Seleucid King Antiochus III found himself on the backfoot in his war against the Roman Empire. His expeditionary force into Greece had been routed, his fleets severely weakened and all his well-stocked and fortified defences in Thrace had fallen uncontested into the hands of his enemy.

What was worse, the Romans had since decided to go on the offensive, crossing the Hellespont (Dardanelles) with an army and invading Seleucid Asia Minor (Anatolia). Their army was commanded by the consul Lucius Scipio, who was seconded by his famed older brother Scipio ‘Africanus’.

Finding himself fighting a war in his own territory, Antiochus could not afford any more blunders. The future of his kingdom as a superpower depended on it. Since his retreat from Lysimacheia, Antiochus had been gathering a vast army from across his large eastern domain: the best the Seleucid Empire could offer. Antiochus aimed to show the Romans the true power of his extensive kingdom.

Where was the Battle of Magnesia?

Following a brief period of manoeuvring, counter-manoeuvring and failed negotiations, the two sides made camp near the town of Magnesia in Lydia, modern-day Manisa in Turkey. Battle was imminent.

Scipio’s army

Scipio’s army centred around its powerful Roman infantry and its flexible Manipular formation. Although aided with an equal number of Italian allies, it was these Roman citizens and their style of fighting that had been key to Rome’s past successes. Only recently had they defeated a Hellenistic army with this formation; now they hoped to do it again.

The Roman army did not consist solely of Italian forces however. Among Scipio’s ranks were some formidable Greek allies.

Coin depicting Eumenes II, ruler of Pergamon.

Image Credit: Public Domain

Achaean aid

One such ally was the Achaean League. Sending a small force under the command of Diophanes – a disciple of their most famous commander Philopoemen – these Achaeans had already proven their formidable skill in the preceding fighting.

For Scipio, these men were undoubtedly a great addition. Yet Diophanes and his Achaeans were not the only Greeks siding with the Romans. One other had staked everything on a Roman victory.

Eumenes II

That man was Eumenes II, ruler of the Attalid dynasty, a small Hellenistic kingdom in Western Anatolia. Bringing his army to Magnesia, that man was determined to expel Antiochus from Asia Minor and stop the threat that Seleucid expansion had posed to his kingdom. His role in the upcoming battle would be critical.

The Seleucid army

Boasting one of the most diverse Hellenistic armies ever seen, Antiochus’ army could not have been more different to that of his Roman counterpart. From Syrian scythed chariots and Gallic cavalry from Asia Minor to Arabian camel riders and swift horse archers from Turkmenistan, his army had come from all four corners of his vast empire.

Despite this diversity, Antiochus’ force was still concentrated around the most iconic unit of the entire Hellenistic period.

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The phalanx

From fighting in the hill fortresses of Thrace, to the plains of Southern Italy and the fast-flowing Hydaspes River in India, the Macedonian phalanx had formed the backbone of  Hellenistic armies across the Ancient World for the past 130 years. Antiochus’ force was no different.

Having 16,000 of these troops – including an elite force of Argyraspides (‘Silver Shields’) – at Magnesia, Antiochus determined that their role in the upcoming battle would be crucial. Their role would be to pin their Roman opponents in place with multiple rows of deadly pikes. Though critical, the phalanx could not win the battle alone.

A syntagma, the basic tactical unit of the Macedonian phalanx.

Image Credit: Shutterstock / History Hit


To aid his powerful infantry, Antiochus positioned nearby one of his most deadly weapons: a small force of Indian War Elephants. These were the tanks of ancient warfare.

Having maintained good relations with the powerful Mauryan Empire ever since Seleucus I’s treaty with the famed Chandragupta over a century before, Indian elephants were a regular appearance in Seleucid armies. Using these beasts also had its risks. If managed effectively, they could easily decide a battle’s outcome. If not, calamity could be just as likely.


Drawing up his forces, Antiochus deployed his powerful war elephants at regular intervals between each section of his phalanx. Appian, writing over 350 years later, claims the sight from the Roman camp:

The appearance of the phalanx was like that of a wall, of which the elephants were the towers. Such was the arrangement of the infantry of Antiochus.

Appian, The Syrian Wars, 6.32

Imagine you are facing one of the most powerful armies of our time. Not only is their infantry highly-trained and equipped with the best weapons available, but spread regularly among these soldiers are some of the most feared military units in warfare. For a Roman soldier at Magnesia, viewing Antiochus’ phalanx intermingled with the formidable Indian elephants was the ancient equivalent. The prospect of confronting such a formation would have been daunting from a distance.

What happened at the Battle of Magnesia?

But looks can be deceiving. During the ensuing Battle of Magnesia of 190 BC, all seemed to begin well for Antiochus. Commanding the right side of his army himself, he successfully pushed back the opposing Romans. But elsewhere things were not going as smoothly.

On Antiochus’ left, things quickly turned to disaster. There, intending to put the opposing Roman forces into complete disarray, Antiochus had deployed many of his deadly scythed chariots to lead the charge. Their shock impact, Antiochus and his commanders likely envisaged, would allow their forces to swiftly cut down any remaining resistance at leisure. In practice, the strategy was sound enough. Yet things did not go according to plan.

Chariot calamity

Eumenes, commanding the opposing Roman flank and seeing this impending chariot attack, acted decisively. Gathering his missile-troops the Attalid king rained stones and arrows on the bladed carts, hailing down death and destruction from a distance. The result was devastating.

Suffering heavily from this barrage of missiles, the Seleucid chariots soon became uncontrollable. Turning from their assailants, they sought safety by any means and charged manically towards the rest of Antiochus’ flank. Calamity was about to ensue.

Running amok, these bladed wagons of destruction carved devastating gaps through Antiochus’ heavily-armoured, mounted troops. The armour of these cavalry units made it almost impossible for them to avoid the deadly scythes. Antiochus’ weapon had backfired completely. It was his army that felt the full force of these brutal war machines. In complete confusion and disarray, the Seleucid left was in turmoil.

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The critical moment

From this confusion, one man saw an opportunity that would decide the encounter. Appian recalls:

Eumenes, having succeeded [in pushing back the chariots…] led his own horse and those of the Romans and Italians […] against the Galatians, the Cappadocians, and the other collection of mercenaries opposed to him […] They […] made so heavy a charge that they put to flight not only those, but the adjoining squadrons and the mail-clad horse.

Appian, Syrian Wars, 6.34

In this one swift, deadly charge, Antiochus’ vast array of powerful cavalry on his right flank evaporated. Eumenes had seen the opportunity and swiftly took it. Defeat followed quickly for Antiochus.

The man himself, caught up in the thrill of a cavalry chase, was blissfully unaware of the calamity. His powerful elephants, too, were rendered all-but useless by being constrained within the Seleucid phalanx. As both flanks crumbled around them, Antiochus’ formidable spearmen found themselves totally exposed. No longer did these men fight for Antiochus, but purely for their own survival.

A Bronze plaque from Pergamum that likely depicts the Battle of Magnesia. Antiochus’ pikemen can be seen on the left, while an Attalid cavalryman and Roman infantry are visible on the right.

Image Credit: Public Domain

Last stand

Encircled, Antiochus’ formidable phalanx prepared a valiant last stand. Forming a square, they protruded their pikes in every direction, presenting any attacking Roman with a wall of death. Finally, however, they succumbed to Roman missiles and the panicking of their own elephants. The resistance crumbled.

Antiochus, expecting to return to a victorious Seleucid army, was shocked. Arriving back at the battlefield to see his great army either routed or slain, the King quickly fled. He had played his last card and lost.

What was the significance of the Battle of Magnesia?

With the destruction of his great force at Magnesia, Antiochus’ hopes of extending his empire into Europe disintegrated. The Roman victory at Magnesia was decisive. But from start to finish, the king’s war against the Romans had been plagued by tactical errors. Magnesia was simply the culmination of such mistakes. Abandoning his dreams to reform Seleucus’ great empire, Antiochus admitted defeat and sued for peace.

Tristan Hughes