Battle of Magnesia (190 BC): Rome Defeats Antiochus III

The Battle of Magnesia was fought in the winter of 190/189 BC near Magnesia ad Sipylum, modern Manisa in western Turkey. A Roman army under the consul Lucius Cornelius Scipio, supported by King Eumenes II of Pergamon, defeated the much larger army of the Seleucid king Antiochus III. The victory led to the Treaty of Apamea and made Rome the dominant power in Asia Minor.

Background

Antiochus III, called “the Great”, had restored the power of the Seleucid Empire from Syria to the borders of India. In the 190s BC he expanded into western Asia Minor and Thrace, regions Rome regarded as within its sphere after defeating Macedon at Cynoscephalae in 197 BC.

In 192 BC, invited by the Aetolian League, Antiochus crossed into Greece. The Romans defeated him at Thermopylae in 191 BC and forced him back to Asia. In 190 BC Roman and Rhodian fleets won at sea, including at Myonessus, and the Rhodians defeated a Seleucid fleet commanded by the exiled Hannibal off Side.

Rome then sent an army across the Hellespont for the first time. It was led by the consul Lucius Scipio, with his famous brother Publius Scipio Africanus, victor of Zama, as his legate.

The armies

Ancient sources give Antiochus a huge army. Livy describes around 60,000 infantry and more than 12,000 cavalry, including a heavy phalanx of 16,000 men, armoured cataphract cavalry, camel-mounted archers, scythed chariots and 54 elephants. The real figure may have been lower, but the Seleucid army was clearly much larger.

The Romans had two legions with Latin and Italian allies, plus the troops of Eumenes II and Greek allies, perhaps around 30,000 men in total. Africanus was ill and stayed behind at Elaea, and Livy indicates that the experienced Gnaeus Domitius Ahenobarbus played a leading role in the battle.

What happened

The battle began on a misty, damp day. On the Roman right, Eumenes sent archers, slingers and javelin men against the scythed chariots. The wounded horses turned back and threw the Seleucid left wing, including camel troops and auxiliaries, into confusion. Eumenes and the Roman cavalry then charged and broke that wing.

On the other side, Antiochus himself led his cavalry against the Roman left, which was anchored on a river. His charge succeeded and he pursued the fleeing Romans to their camp. There the tribune Marcus Aemilius rallied the guards and fugitives, and the king’s attack stalled.

Meanwhile, the Seleucid phalanx in the centre was left exposed. It was drawn up 32 ranks deep with elephants placed in the gaps between its sections. Roman missiles panicked the elephants, the formation lost cohesion, and the infantry was finally broken and slaughtered. Antiochus fled to Sardis and then to Apamea.

Key people

Antiochus III had ruled since 223 BC and earned his title “the Great” through an eastern expedition that took him as far as Bactria and the borders of India. He also won Coele-Syria from Ptolemaic Egypt at the Battle of Panium in about 200 BC. At Magnesia, his personal courage in leading the cavalry charge contributed to his defeat, because he lost control of the wider battle.

Eumenes II of Pergamon was Rome’s most important ally in Asia. He had every reason to want Antiochus weakened, and his cavalry and light troops did much to win the battle. Hannibal, who had joined Antiochus as an exile, did not command at Magnesia; ancient writers suggest the king made little use of his advice.

Losses

Livy reports Seleucid losses of about 50,000 infantry and 3,000 cavalry killed, with 1,400 captured. He gives Roman losses as only about 300 infantry and 24 cavalry, with 25 of Eumenes’s men. Modern historians regard these figures as greatly exaggerated in Rome’s favour, but agree that the Seleucid defeat was total.

The Treaty of Apamea

The peace was confirmed in 188 BC at Apamea in Phrygia. Antiochus gave up all territory west of the Taurus Mountains and agreed to pay 15,000 talents, 12,000 of them in annual instalments over 12 years, one of the largest indemnities in ancient history. He also surrendered his elephants and all but 10 warships, and handed over 20 hostages, including his son, the future Antiochus IV.

Rome took no land in Asia for itself. It gave most of the territory to its allies, Pergamon and Rhodes, which grew greatly in power. Lucius Scipio received the honorary name Asiaticus. The treaty also required the surrender of Hannibal, who fled and eventually found refuge in Bithynia.

Timeline

• 196 BC: Antiochus III crosses into Thrace, alarming Rome.
• 192 BC: Antiochus lands in Greece at the invitation of the Aetolians.
• 191 BC: The Romans defeat Antiochus at Thermopylae.
• 190 BC: Roman and Rhodian naval victories; a Roman army crosses into Asia.
• Winter 190/189 BC: Battle of Magnesia.
• 188 BC: Treaty of Apamea ends the war.
• 187 BC: Antiochus III dies while raiding a temple in Elymais.

Why it matters

Magnesia was the first great Roman victory in Asia. It broke the Seleucid hold on the Aegean and showed that the Hellenistic kingdoms could not match Rome. The heavy indemnity weakened the Seleucids, and Antiochus IV, raised as a hostage in Rome, later faced the Maccabean Revolt in Judea.