Battle of Magnesia The Battle of Magnesia was the concluding battle of the Roman – Syrian War , fought in 190 BC near Magnesia ad Sipylum on the plains of Lydia ( modern Turkey ) between Romans , led by the consul Lucius Cornelius Scipio and his brother , the famed general Scipio Africanus , with their ally Eumenes II of Pergamum , and the army of Antiochus III the Great of the Seleucid Empire . The resulting decisive Roman victory resulted in Roman domination over the internal affairs of a large part of the territory once controlled by the Seleucid Empire . The main historical sources for this battle are Livy and Appian . The two armies . Antiochus was driven out of Greece following the defeat of his expeditionary force at the Battle of Thermopylae ( 191 BC ) . The Roman navy with the Rhodians and other allies outmaneuvered and defeated the Seleucid navy , permitting the Roman army to cross the Hellespont . The Roman army operated under the commands of the consul Lucius Cornelius Scipio Asiaticus , younger brother of Scipio Africanus , who accompanied him as legatus . The Carthaginian general and dire enemy of the Roman Republic Hannibal Barca , had fled to Antiochus ' court after his defeat at the Battle of Zama and the end of the Second Punic War . Some believe that Hannibal was present at Magnesia . This is false , however , because Hannibal , who had commanded the fleet and lost at Eurymedon , had retreated and then fled to Crete for fear that Antiochus would lose and turn him over to the Romans . In anticipation of the battle , Antiochus set up an entrenched camp protecting the approach to Sardis and his fleet base at Ephesus . According to both Livy and Appian , he posted his 16 , 000 strong phalanx , armed in the Macedonian fashion in the center in brigades ( taxeis ) of 1 , 600 men , 50 men wide and 32 men deep . He ordered intervals to be formed among the taxeis in which he placed 2 elephants each . On the right wing , next to the phalanx , he arrayed 1 , 500 Gallograecian infantry , 3 , 000 Galatian mail clad cavalry ( cataphract i ) and 1 , 000 agema cavalry , his royal household guards . Behind them he kept 16 elephants in reserve . Next to the agema , he placed a cavalry corps Livy calls argyraspides , 200 or 1 , 200 Dahae horse archers , 3 , 000 Cretan and Trallean light infantry , 2 , 500 Mysian bowmen , Cyrtian slingers and Elymaean archers . On the left , Antiochus arrayed another 1 , 500 Gallograecian infantry , according to Appian men from the tribes of the Tectosagi , the Trocmi and the Tolistoboii , 2 , 000 Cappadocians similarly armed and a miscellaneous force of 2 , 700 . Next to them , he posted 1 , 000 heavy horsemen , the Companions , 3 , 000 more cataphracti and probably another 1 , 000 men of the agema . In front of them , he placed the scythed chariots and a unit of dromedary , camel - borne Arab archers . His left wing was completed with a corps of Tarentines , 2 , 500 Gallograecian cavalry , 1 , 000 newly enlisted Cretans , 1 , 500 Carians and Cilicians similarly armed , and the same number of Tralles . Then came 4 , 000 peltast s , Pisidians , Pamphylians and Lydians , next to these Cyrtian and Elymaean troops equal in number to those on the right wing , and finally sixteen elephants a short distance away . Antiochus retained command of the horse on the right wing in person ; his son Seleucus and his nephew Antipater commanded the left . Philip , the master of the elephants , commanded the phalanx , and Mendis and Zeuxis the skirmishers . The Romans arrayed in their customary triple line formation with their left wing resting on the river . The Roman reinforced legions occupied the center of this formation and the Latins , the Ally legions , on their wings . In all , there were 20 , 000 men of the legion . Behind them , Scipio held his 16 elephants in reserve , fully aware that the African elephants could not face the larger Indian stock on equal terms . On the right Scipio placed the allied Pergamene army under Eumenes and the Achaean peltasts , 3 , 000 in all to cover the flank of the legions . Next to them he placed his cavalry , nearly 3 , 000 strong , 800 of them Pergamenes , the rest legionary cavalry . According to Livy , in the extreme right he posted the Trallian and Cretan horsemen , each body numbering 500 troopers , but most probably , these are the light troops and archers named by Appian to be intermingled among the cavalry . Livy also mentions 2 , 000 Macedonian and Thracian volunteers , who are left to guard the Roman camp . Domitius was stationed with 4 squadrons of cavalry on the right wing , Scipio kept command of the center and gave command of the left to Eumenes . In all , both writers agree that the Roman army was about 30 , 000 strong and the Seleucids about 70 , 000 . However , historian Grainger argues that the two armies might have been not that numerically different and supports that the Romans fielded about 50 , 000 men as did Antiochus . A popular anecdote regarding the array of the two armies is that Antiochus supposedly asked Hannibal whether his vast and well - armed formation would be enough for the Roman Republic , to which Hannibal tartly replied , " " quite enough for the Romans , however greedy they are . " " The battle . The Romans wished to fight this battle , before a new consul was sent out from Rome and winter would lead the campaign to a halt . Scipio had successfully crossed the river and set up a camp only about 4 km from the camp of Antiochus . Scipio ' s further advance from his camp was made with the river protecting his left , where he would rest his arrayed legions . Except for 4 squadrons ( turmae ) all the allied cavalry was on its right when the battle started . As in almost all ancient battles , different reconstructions are possible . Appian has the battle start on the Seleucid left with a failed attack by the scythed chariots which disrupted the Seleucid cavalry on that wing . Roughly at the same time , there was a charge on the right by the Seleucid cavalry wing commanded by the king himself , which broke their opposing infantry leading to a pursuit by the Seleucid horse , leaving the field to unsuccessfully attack the Roman camp . The Roman ally Eumenes , commanding all their cavalry on the right of the Roman - Allied army counterattacked the Seleucid left , already disrupted by the scythed chariots , and broke it . In the center of the battle line , the Seleucids had arrayed their pike phalanx with elephants in intervals between the taxeis . They seem to have been unable to really participate in the battle , having soon been encircled by the victorious enemy horsemen . Forming squares facing all sides , the phallangitai tried to march off the battlefield but their efforts were not successful , as they broke when the elephants panicked . Eventually , after further fighting , the Seleucid camp fell . Aftermath . After an armistice was arranged between Antiochus and Rome , the Roman army waged a campaign against the Galatia ns which politically undermined the Seleucid position in Asia Minor . The Romans had had a tremendous advantage throughout their campaign from their much more limited political objective . All the small powers could ally themselves to Rome because Rome sought no political annexations at this time . Conversely , Antiochus desired to conquer Asia Minor , as he saw himself in the vein of Alexander the Great . The Aegean Sea was a natural frontier for a state based in Babylonia , as Xerxes discovered long ago . If Antiochus had wanted to advance west into Greece , he needed to turn his state into the leading naval power in the Mediterranean , from nowhere , before sending his army west . The treaty forced upon Antiochus III by the victorious Romans was crippling , in the Treaty of Apamea Antiochus was forced to pay a huge war indemnity of 15 , 000 Talents along with giving up significant territory in Asia Minor . The Taurus Mountains became the new frontier . The Seleucid navy was limited by treaty , and their squadrons of war elephants destroyed . It weakened the already fractious Seleucid Empire and halted all ambitions of Antiochus III in becoming a latter day Alexander in his own right . Polybius states the financial burden of war indemnity forced Antiochus III to loot temple treasuries . This alienated Seleucid subjects and further reducing the dynasty ' s prestige already sharply reduced by the decisive defeat suffered against the Romans .