Battle of Magnesia 190 BC – Roman Legions Vs Hellenistic Phalanx

PART 2:

The Pergamene cavalry struck the unorganized Seleucid infantry lines like a wrecking ball. The ferocity of the Roman Pergamene charge was so fierce that most of the Seleucid left decided fighting was futile. They turned and fled the battlefield. A loyal but small section of elite Seleucid heavy cavalry refused to cower.

They stood their ground and fought fiercely. But ultimately their struggle was for nothing as they were abandoned, outnumbered, and surrounded. Once they were swiftly dealt with, the Roman right gave pursuit to the fleeing enemy ensuring that they didn’t regroup and return to the battlefield later. Although it was a complete catastrophe, the destruction of his entire left flank, Antiochus was not a man to be defeated by minor setbacks.

He took action. He organized his heavy cavalry on the Seleucid right and prepared them for a major offensive. Leaving behind his infantry and war elephants, he personally led his heavy cavalry directly toward the Roman left flank. Stationed at the Roman left was Roman heavy legionaries. Not an ideal opponent to attack head-on.

Nevertheless, Antiochus had the heaviest and most elite cavalry in the known world. He had full confidence in their superiority. The Roman skirmishers were cut down swiftly. Struck first with the lighter hastati at the front, who were not as well armored as their principes or triarii comrades. The charge was so devastating that men were thrown back up to 10 feet, disrupting the entire formation.

The front line of hastati attempted to close ranks and form one single defensive line to better defend against this assault, which was the right maneuver in the situation. But the superiority of the Seleucid cavalry was too much to bear and had the Roman lines on the back foot. The Seleucid cavalry continued to carve deeper and deeper into the Roman lines.

Their mounted riders were covered in metal armor, making it difficult for the Roman legions and their short swords to land a killing blow. Even their horses were partially covered in armor from the front, which made it all the more difficult to eliminate the threat. Then the Seleucid cavalry drove deep into the Roman flank.

Roman cavalry attempted to stop this maneuver, but were defeated under the immense pressure.  [screaming] [cheering] [cheering]  The Seleucid cavalry were winning this fight. They slowly began to envelop the Roman right. It was not certain as to what happened next, besides the fact that the Roman right retreated all the way back to their camp.

Perhaps the men lost heart and tried to save themselves. Or perhaps Scipio gave orders for his right to tactfully retreat as opposed to being enveloped. Whatever the case, Antiochus’ cavalry pursued the Romans all the way back to their camp, where the Roman infantry reorganized themselves into a viable defense.

Meanwhile, the Roman center marched on the Seleucid center. Antiochus and his cavalry contingents were by this stage too far away from the main battlefield and were not aware of what was occurring, nor had they received any news. Luckily for Antiochus, he had competent commanders overseeing the infantry on his right wing.

They decided the best course of action was to reposition the pike phalanx infantry towards the center to reinforce it against the oncoming Romans. The elephants and their riders weren’t as cooperative, it seems, as they fled the battlefield and took no further part. The worst possible scenario had come true for Antiochus’s army.

The Roman right, which had pursued the Seleucid left from the battlefield earlier in the day, had returned back to the battlefield. They were now positioning themselves to fully surround the isolated Seleucid center. But still, even with this advantage, the Romans were faced against perhaps the most elite units in the known world.

The Macedonian phalanx, which was the core part of any Hellenistic general’s army during the period. Together, they banded tightly into disciplined ranks with their long sarissa pikes ready to be deployed to full effect. They were anticipating that their general leading the cavalry would return at any moment to even the odds.

Fully surrounded, the Seleucid center had no way of escape, and there was still no sign of reinforcements on the horizon. They were on their own. Here on the plains of Magnesia, where the two greatest military systems of ancient antiquity once again collide on the battlefield. It would be phalanx versus legion in a straight-on engagement.

The last time these systems fought in a major battle was at Cynoscephalae 7 years prior, where the Roman legions, after a long struggle, bested the Macedonian phalanx, thus becoming supreme rulers of Greece. Realizing time was of the essence, Scipio gave the orders to attack. Missiles rained down atop the Seleucid center, cutting into the ranks, inflicting heavy casualties.

The phalanx troops were equipped with smaller, rounded shields, and were not effective at repelling immense projectile fire. Thus, the casualties continued to mount. Once enough damage was dealt, Scipio gave the order to surround their position and attack. Legions, light troops, and cavalry diverged onto the Seleucid lines.

Even with the odds stacked against them, the Seleucid phalanx divisions were still a major threat. The Roman troops had to thread carefully. To attack a phalanx frontally was terrifying. The long pikes projected outward in layered rows, making direct assault extremely difficult. The Romans had to attack weak spots and penetrate any gaps they could locate.

As once disrupted, the phalanx became dangerously inflexible and would usually crumble. Fortunately, the Roman legion was built differently. Roman manipular formations allowed smaller units to maneuver independently. As the battle intensified, the Roman and allied troops exploited gaps in the Seleucid line. Roman soldiers pressed into these gaps.

Once the integrity of the phalanx began breaking apart, the advantages of the sarissa vanished. The fight became fragmented and chaotic. In close quarters, Roman infantry excelled. The legionaries stabbed beneath shields, attacked isolated groups, and gradually dismembered the giant formation piece by piece. The Seleucid center began collapsing.

Once the phalanx lost cohesion, the battle turned into slaughter. By the time Antiochus returned from the right wing, the battle was already lost. His center had collapsed. His left had vanished. The army of the Seleucid Empire dissolved into retreat. Antiochus’ pursuit on the right wing removed him from the decisive phase of the battle.

His decision to give chase instead of managing his army ultimately led to his defeat. Another key feature worth mentioning was the fact that Antiochus relied too heavily on spectacle weapons, scythed chariots and elephants, that often created as much danger for his own troops as for the enemy. Whereas the Romans stuck to the basics, relying heavily on infantry and superior training.

Ancient historians report catastrophic casualties for Antiochus’ army, likely exaggerated as ancient numbers often were, but the defeat itself was unquestionably devastating. The defeat shattered Seleucid power in Asia Minor. In 188 BC, Antiochus was forced to accept the harsh treaty of Apamea. The terms were severe.

After Magnesia, no Hellenistic kingdom could realistically challenge Rome on equal terms again. The age of Alexander’s successors was fading. The Roman century had begun.