At the beginning of the 2nd century BCE, two major powers vied for the Mediterranean. In the west, the Romans had recently defeated the Carthaginians and, having crossed to Greece, the Macedonians. Concurrently, Antiochus III (223-187BCE), king of the Seleucid Empire, earned the title the Great by re-establishing Seleucid power in Asia Minor, seizing Syria from the Ptolemies, and campaigning in central Asia.After the Roman victory over the Macedonians at Cynoscephalae in 197 BCE, Greece was contested by the Romans and Seleucids. Neither initially desired war but in less than a decade they were drawn into a fateful clash that ended at Magnesia.The Freedom of the GreeksAntiochus III, 1st century BCE, Italy. Source: Muse du LouvreAfter their removal of Macedonian control over Greece in 197 BCE the Romans did something unexpected. They withdrew their legions and proclaimed the Greeks free. The various Greek city-states, federal leagues, and kingdoms were to govern themselves. This Roman settlement created ambiguity. Roman troops had withdrawn but everyone still looked, expectantly or nervously, across the Adriatic to Rome. Few could doubt that the Romans were a major power in Greece but the limits of their interest were uncertain.While the Romans were proclaiming the freedom of the Greeks Antiochus was bolstering the Seleucid Empire. In Asia Minor, this saw the Seleucids take or threaten cities previously under the control of the Macedonians, places that the Romans could claim they had liberated. Crossing into Europe Antiochus built a strong Seleucid presence in Thrace. For Antiochus, he was within his rights as a Hellenistic king to re-establish control over the territory which his ancestors had held.Diplomatic exchanges between Antiochus and Rome in the years 197-192 BCE were cautious and tense but not overtly hostile. Some scholars have suggested that while neither side pushed for war there was a misunderstanding that drove them to it. Antiochus controlled his empire through direct occupation or treaties. Roman control was more informal and based on political friendship and the propaganda of freedom for the Greeks. What to the Romans looked like an area under their influence and bound to them seemed to Antiochus a land the Romans had little interest in and one which, in some regions at least, was well within his dynastys sphere of interest.The War in GreeceSilver coin of Antiochus III, 3rd-2nd century BCE, Syria. Source: British MuseumIt was the smaller powers between the two empires that provoked war. The Seleucid revival in Asia Minor left the small Attalid kingdom of Pergamon vulnerable. King Eumenes II (197-159 BCE) turned down a Seleucid alliance and talked up the danger of Antiochus. This task was not difficult. Antiochus advances in Thrace could be seen as threatening to both the Roman settlement of Greece and ultimately Italy. These fears grew when Romes bitterest enemy, Hannibal the Carthaginian, visited Antiochus court in 195 BCE.In Greece, the Aitolian federal state had grown dissatisfied with its previous partnership with the Romans. As they looked to secure their ambitions they turned to Antiochus. In 192 BCE, the Aitolians attempted to seize control of central and southern Greece. A series of coups they plotted largely failed but with the situation in Greece now unstable they called on Antiochus to arbitrate their disputes with the Romans.Antiochus seized the opportunity. If the Roman settlement in Greece could be replaced by a Seleucid system of alliances there would be no more need to negotiate with the Romans about how their policy of freedom applied to Seleucid lands. At the very least any future war would take place in Greece and Antiochus would gain allies.Antiochus badly miscalculated the Roman reaction. In late 192 BCE, he landed in Greece with a small force of up to 18,000 troops, clearly looking to the Aitolians and future Greek allies for support. While they did make progress and some reluctant allies, the Roman response was decisive and soon the legions were dispatched back to Greece.According to Grainger, the limited size of Antiochus force may show that the king did not expect the Romans to fight and that a lighter presence was more likely to win over Greek allies. But it meant that Antiochus was not prepared to fight in Greece. He hastily retreated to the famous mountain pass at Thermopylae in 191 BCE but was defeated trying to hold the pass. Having received little support from the Greekseven the Aitolians sent only a small force to ThermopylaeAntiochus was forced to withdraw to Asia. The Greek expedition was over less than a year after it had begun.Modern view of Thermopylae. Source: Livius.orgInvasion of AsiaAfter the disaster in Greece Hannibal warned Antiochus that the Romans would not stop in Europe. The king tried to negotiate but following their swift victory and with more reinforcements on the way the Romans were uninterested.While the Roman army dealt with the Aitolians in Greece the combined forces of Rome, Rhodes, and Pergamon fought for control of the Aegean Sea. The Rhodians played a crucial role as they prevented Hannibal from bringing reinforcements, and froze him out of the war, before joining the Romans to defeat the Seleucid fleet at Myonessus in 190 BCE.Having lost control of the sea Antiochus withdrew from the coast and prepared himself in the center of Asia Minor. The Roman invasion force under the recently elected consul Lucius Cornelius Scipio could now make over to Asia. This command had been secured by the consuls more famous brother Publius Scipio Africanus, the most renowned Roman general of his day and the man who had defeated Hannibal.Image of a Rhodian trireme, Lindos. Source: Wikimedia CommonsAntiochus made one final bid for peace after the Romans landed in Asia. However, there was no sense of compromise from the Romans and the terms offered imposed heavy costs on the Seleucids and demanded the surrender of all Asia Minor. Antiochus could not agree to these terms and withdrew from the coast some 60 kilometers inland and awaited the Romans at Magnesia and Sipylum.Advance to MagnesiaThe Scipios led the first Roman army to reach Asia, consisting of 30,000 to 40,000 troops, to confront Antiochus. At its core were 20,000 heavy infantry consisting of two Roman legions and two Italian Latin contingents, each around 5,400 strong. 3,000 lightly armed Pergamene and Achaian troops and 3,000 cavalry, of which 800 were again from Pergamon, were to support the battle-winning infantry. Smaller numbers of Cretans, Macedonians, and Thracians made up the rest of the army. The Romans were also accompanied by 16 African elephants though they played little part in the battle and were kept back as they were outnumbered by Antiochus larger Indian elephants.The Seleucid army was said to be much larger and much more diverse. While our sources claim Antiochus was relaxed about the prospect of a Roman invasion of Asia he had made extensive preparations. According to Professor Bezalel Bar-Kochva, the army Antiochus gathered at Magnesia drew on the resources of his vast empire and gathered 60,000 infantry and 12,000 cavalry.Roman Republican soldier, 2nd century BCE. Source: Muse du LouvreAt its heart was the famed Macedonian phalanx of massed pikemen. These 16,000 soldiers would form the center of Antiochus line. The nearby regions of Cappodocia and Galatia provided contingents with others coming from Seleucid territories in Media, modern Iran. Split into two equal contingents were 6,000 cataphracts, heavily armored horsemen. Macedonian armies had a long cavalry tradition but the addition of armor was an innovation Antiochus may have picked up from campaigns further east. Another notable feature of this army was the deployment of scythed chariots. With blades sticking out from the wheels these chariots looked terrifying and had been used before by the Seleucids without becoming a common feature.In late 190 BCE (some accounts put the battle in January 189 BCE) these two armies stood at opposite ends of a flat plain between two rivers outside Magnesia. The Romans were outnumbered but the sources generally give the impression that the Romans were confident and eager for battle. The Romans had defeated Hellenistic armies before. Roman victories in Greece and the Aegean and Antiochus abandonment of his territories in Europe at the Roman approach surely boosted their confidence further.Battle of MagnesiaThe Macedonian phalanx. Source: Livius.orgAfter the arrival of the Romans at Magnesia neither side moved. Antiochus, on chosen ground, could wait for the Romans to come to him. Lucius Scipio could not. It was late in the year and the Romans had to decide whether to fight or disburse to winter quarters. After some hesitation Scipio ordered the army to advance to a slightly narrower part of the plain. Seeing the enemy advance Antiochus also decided the time for battle had come.The Romans deployed their forces in their traditional formation with three lines of heavy infantry in the center, Eumenes with the Pergamene and Greek cavalry and auxiliaries on the right, and their left next to a river. Antiochus largely matched this layout but with some interesting variations. Interspersed among the phalanx in the center were groups of elephants adding to the terrifying spectacle of the wall of pikemen. To both the left and the right Antiochus stationed his cataphracts and supporting cavalry. The king himself was with the right wing while to the left the scythed chariots lined up.Seleucid or Parthian Cataphract, 3rd-2nd century BCE, Iraq. Source: British MuseumThe day of the battle began with mist and clouds which reduced visibility. The later Roman historian Livy states this gave an early advantage to the Romans since Antiochus larger army was so spread out that the king could not see the full picture across the battlefield.Once the battle began, Antiochus plan became clear. This was not to be another battle between legion and phalanx. Instead, Antiochus pinned his hopes on his cataphracts and chariots. The plan started with spectacular success. The armored cavalry of the Seleucid, right under Antiochus himself, smashed through the Roman lines by the river. This was a rare occasion in which the heavy infantry of the Romans was broken by a cavalry charge. Following up this success was more difficult. The Roman left was broken, but not destroyed, and enough troops rallied around the Roman camp to halt Antiochus momentum, forcing the king to eventually turn around without achieving anything decisive.In contrast to the success on the right, everything went wrong on the Seleucid left. The use of scythed chariots backfired as the Romans and Eumunes targeted the horses with javelins, arrows, and sling stones until they became uncontrollable. The panicking horses turned back into their own lines disrupting the cataphracts. Seeing the disorder, Eumenes charged, and suddenly the Seleucid left was fleeing. In the center a similar story played out. The elephants stationed among the phalanx to give it extra strength became uncontrollable when targeted. As they broke they disrupted the cohesion the phalanx relied on to survive, and the Seleucid center joined the left in its rout.By the time Antiochus understood what was happening it was too late. Roman sources claim more than 50,000 Seleucids were killed at the cost of less than 400 Romans and Greeks. The numbers are probably exaggerated but once the infantry in the center was isolated it is unlikely many survived the massacre.Where the Battle Was LostSilver coin of Antiochus III with a Seleucid elephant, 3rd-2nd century BCE, Syria. Source: British MuseumAntiochus approach to the battle deserves some comment. A much later historian, Appian, criticizes Antiochus for concentrating on his cavalry rather than the phalanx which he left crowded in a narrow space. The innovation of placing elephants within the phalanx also did more harm than good. However, it is possible that the focus on cavalry shows a clear line of thought from Antiochus and an attempt to overcome previous failures.Antiochus was well aware that Hellenistic armies with their focus on the phalanx had struggled and been defeated by Roman legions. He was well-informed about the defeat of the Macedonian phalanx at Cynoscephalae in 197 BCE. During the expedition to Greece he had sent officers to the battlefield. There, Roman legions had broken up and destroyed a phalanx. Antiochus, therefore, avoided another contest of phalanx and legion.The turn to heavy cavalry and chariots was an attempt to innovate and win the battle elsewhere rather than simply waiting for the phalanx to lose against the legions. On the right this plan worked. Modern historians like Grainger and Bar-Kochva argue that the failure was in the use of chariots, a previously unreliable weapon, and the inadequate protection for them against enemy skirmishers.The plan he came up with for the battle of Magnesia shows Antiochus was an intelligent and innovative commander. Unfortunately he may have learnt the wrong lesson from Cynoscephalae. That battle was fought on uneven ground allowing the more flexible Roman legionnaires to disrupt the tight formation of the phalanx. The flat plain of Magnesia could have been a more suitable place to test the phalanx against the legion on its favored terrain.End of Seleucid Asia MinorMap showing the increase in Pergamene (blue) and Rhodian (green) following the Treaty of Apamea, 188 BCE. Source: Wikimedia CommonsAs Antiochus fell back toward Syria after the defeat, Seleucid power in Asia Minor and Anatolia went with him. A peace was soon agreed, the Peace of Apamea. Its terms spelled the end of Seleucid rule north of the Taurus mountains, essentially the Seleucids lost all of modern Turkey. As they had done in Greece, the Romans would not take these lands directly. Instead, Rhodes and Pergamon, who had both been essential to the Roman victory, divided the lands between them.The Seleucid Empire was not finished yet. But, in a short war that lasted just over two years, 192-190 BCE, the Romans had wiped out the progress Antiochus had spent decades on in the west. Stripped of some of its richest provinces, the Seleucids would never recover.Bibliography:Bar-Kochva, B (2008). The Seleucid Army:Organization and Tactics in the Great Campaigns. Cambridge University Press. New YorkChaniotis, A (2018). Age of Conquests:The Greek World from Alexander to Hadrian. Harvard University Press. Cambridge, Mass.Grainger, J.D (2015). The Seleukid Empire of Antiochus III: 223-187 BC. Pen & Sword.Gruen, E (1984). The Hellenistic World and the Coming of Rome, vol.1. University of California Press. London