# Siege of Antioch (51 BC)

The Battle/Siege of Antioch (or Battle of Antigonia) was fought in October 51 BC between the Romans and the Parthians, following an invasion by the latter against the region of Antioch in Syria and their unsuccessful attempt to besiege the city.

## Historical context

Roman–Parthian relations had deteriorated following the reckless expedition of Marcus Licinius Crassus (the triumvir), which had culminated in the disaster of the Battle of Carrhae and the death of Crassus himself in 53 BC. Surena's victory over the Romans at Carrhae was devastating and had enormous consequences. It halted Roman expansion, gave Mesopotamia back to the Parthians, and consolidated the Euphrates as the boundary between the two powers. It placed Persia on an equal footing with Rome, making them political rivals for the next seven centuries. Partly to avenge that unjustified aggression and partly to take advantage of the weakness of the Romans in the East, in 51 BC the Parthians organized an incursion against the Roman province of Syria and in particular against its capital Antioch.

### Prelude

The Parthian expedition was nominally led by Prince Pacorus I, who was, however, a child. The actual command therefore fell to the experienced general Osaces. Cicero, who was at the time governor of the neighbouring province of Cilicia, reported that he had learned of the invasion on a date which corresponds to 20 September 51 BC. The province of Syria was governed by Gaius Cassius Longinus, one of the future assassins of Julius Caesar, who had few troops at his disposal and who was also waiting to be replaced by the new governor Bibulus, who had already left Rome for that purpose but of whom there was no news at the time.
Having crossed the Euphrates, the Parthians initially had an easy time plundering the surroundings of Antioch. Their aim was raiding, not territorial conquest, and their forces traditionally had their core in the cavalry. One of their detachments also penetrated into Cilicia, but was annihilated near Epifenae in an equestrian battle by Cicero's troops, who even rushed in person to guard the pass of Mount Amanus to block the enemy's entrance and also to bring help to Cassius if necessary. In fact, he reached Tarsus by forced marches on 5 October 51 BC.
Meanwhile, Cassius, whose forces were not sufficient to face Osaces in the open field, had to remain shut up in Antioch. This inaction pushed the Parthians even to attempt a siege of the city, a type of operation in which the Parthians had no experience and for which they lacked adequate equipment. The Romans thus succeeded in repelling them. The Parthians then turned against the city of Antigonia in Syria.

## Theatre of military operations
### Battle

According to Cassius Dio, in this case the obstacle the Parthians encountered were the thick woods surrounding the city. They planned to cut them down, but the undertaking took a long time and did not yield the desired results, while in the meantime Cassius' forces attacked the groups they surprised dispersed. In the end, the Parthians gave up and planned to strike other areas, but Cassius, who had participated in the disaster of Carrhae a few years earlier and had performed better than his commander in chief at the time, had made his bones and turned against the Parthians a stratagem in which they were masters: a small group of Romans confronted them and immediately afterwards feigned a flight. Pursued, he led the Parthians into an ambush, where many of them were killed. On a scale and with an indisputably lesser importance, the defeat of Carrhae was returned to the Parthians, and in Rome it was considered a "revenge for Carrhae". It must have been a battle of some importance, if only because Osaces himself died there. According to Cassius Dio, he perished in the battle, while according to Cicero, who was present in the same theater of operations and was therefore probably better informed, he was seriously wounded and died from the consequences of the wound some time later. Cassius informed the Senate of the victory with a message dated October 7, 51 BC, which places the battle, if not on the same day, then immediately before. The parthians later retreated beyond the Euphrates, and Rome annexed back the province Osroene, including the city of Carrhae.

### Consequences

After the battle, the Parthians abandoned the region of Antioch, while the Romans wintered in the fortified camps of the Cyrrhestica to guard the fords of the Euphrates. In a letter as early as 8 October 51 BC, Cicero reported that there were no more Parthians in the area and, although some armed bands had been observed, he judged them to be composed of Arabs armed in the manner of the Parthians. For the latter, the defeat and death of Osaces must have represented a considerable blow, but it is also true that Cicero admitted to having the impression that the Parthians were retreating more because there was nothing left to raid than because of the defeat they had suffered and with the annihilation of their own army.