When Antiochus III (the Great) inherited the Seleucid throne, he was acting as governor of the eastern Satrapies of the empire. One of his first decisions was the appointment of his successors. He chose two brothers – Molon and Alexander, who received command of Media and Persia. The following year, while Antiochus was preparing for a war with Egypt, Molon went into open revolt, and was joined by his brother. Antichus first responded by sending one of his generals, Xenoetas, against Molon, but he was defeated in 221.
This forced Antiochus to take command of the war against Molon in person. Thanks to Polybius we can follow the route he took from Syria to the site of the final battle. The army assembled at Apamea, on the upper reaches of the Euphrates. From there they headed east, to Anthioch-Nisibis, close to the Tigris, where they rested for forty days during the middle of the winter or 221/220 BC. From there they then moved south to Libba, on the Tigris. There they crossed to the east bank of the river, and continued south towards Dura (or Doura), then under siege by the forces of Molon.
Molon had begun his rebellion in Media, with his main powerbase apparently in the region of Apollonia, in the west of Media, and east of Dura. After defeating Xenoetas, he had turned south, capturing Babylon then turning north, expanding his control along the Euphrates. When he learnt that Antiochus had reached the Tigris, Molon decided to return north to his stronghold in Apollonia. Accordingly, he crossed the Tigris and made a dash for Apollonia.
Unfortunately for Molon, after lifting the siege of Dura, Antiochus had also moved towards Apollonia. As Molon was approaching the hilly country that was his target, the Royal army was leaving Apollonia. Somewhere in the territory of Apollonia the two armies ran into each other when their respective advance guards met while crossing a range of hills.
Molon could not entirely trust his army. The phalanx contained Greek settlers, who tended to be loyal to the royal house. Accordingly he attempted a night raid on the royal army, which was abandoned after ten of his men deserted. The next morning the two armies took the field for a formal battle.
Polybius gives us an account of the deployment of the two armies. Antiochus placed his lancers on the far right, then from right to left placed his Cretan allies, then his Gallic mercenaries, then Greek mercenaries then the phalanx. He had ten elephants, which were placed at intervals in front of the line. He placed infantry and cavalry reserves between the two wings. Antiochus took command on the right, leaving command on the left to Hermeias and Zeuxis, two of his generals.
Molon’s camp was apparently in some confusion after the failure of the night raid. However, he was able to restore some order, placing his cavalry on the two wings, with all of his heavily armed troops in the centre. His light troops, amongst them slingers and archers, were placed behind the two wings. In place of elephants, he had scythed chariots, which he placed in front of the main line. Molon took command of the right wing, facing Hermeias and Zeuxis, and gave command of the left to his brother Neolaus, who would have to face Antiochus.
The battle was decided on Molon’s left. Once the troops there realised that they were facing the king, they changed sides. Even though the troops on the right remained loyal, Molon knew that the battle was lost and committed suicide on the battlefield. Neolaus escaped to Persia, where he too committed suicide, although only after killing Molon’s family to prevent them falling into Antiochus’s hands.
In the aftermath of the battle Antiochus regained control over Media and Persia. His advisor Hermeias was gaining a bad reputation, and in the aftermath of the battle Antiochus had him assassinated. Antiochus was now free to return to Syria and continue the war against Egypt (Fourth Syrian War).