Marcus Licinius Crassus arrived in Syria in the spring of 54 bc with plans to invade the Parthian Empire, which centered on present-day Iran. Plutarch, who wrote the most detailed account of the campaign, suggests Crassus wanted to match the military exploits of Caesar and Pompey, his partners in the First Triumvirate.
Crassus started slowly. During the latter half of 54 bc, he garrisoned several cities in northern Mesopotamia before wintering in Syria. He was awaiting his son Publius, who was headed east with 1,000 Gallic cavalrymen.
When Crassus finally got moving the next year, subordinates urged him to advance down the Euphrates. Instead, he marched directly into Parthia past the fortified city of Carrhae (present-day Harran in southeastern Turkey). The Roman force consisted of seven legions (roughly 35,000 infantry), accompanied by 4,000 light infantry and a similar number of cavalry. Crassus deployed the army in hollow squares.
The smaller Parthian force under General Surena consisted entirely of cavalry. There were 9,000 mounted archers and 1,000 cataphracts—armored men with long spears on armored horses.
Battle was joined sometime in June of 53 bc. The cataphracts initially charged, but were frustrated by the Romans’ close formation and interlocked shields. Then the Parthian-mounted archers went to work. Their composite bows launched arrows with enormous force, sufficient to penetrate armor.
The Romans expected the Parthians to run out of arrows, after which they could advance to close quarters. It didn’t happen. Surena had organized a camel train to resupply his archers. In frustration, Crassus ordered Publius to take a detachment (including the Gallic cavalry) and charge the enemy. The Parthians feigned retreat, and Publius fell for it, pursuing enthusiastically until isolated from the main Roman body. Then the Parthians turned, killing Publius and nearly annihilating his force. With Publius’ head mounted on a spear, they rode back to renew the main assault.
By nightfall, the desperate Romans resolved to slip away. The retreating force abandoned 4,000 wounded legionaries, whom the Parthians slaughtered. The Romans first fell back to Carrhae, but lacking provisions, were again forced to withdraw. Surena then arranged to meet Crassus, ostensibly to discuss terms. But it was a trap. In the resulting fight, Crassus was killed, his severed head sent north to Parthian King Orodes II, who was campaigning in Armenia. In the end, the Parthians killed some 20,000 Romans and captured 10,000.
- l Strike while your political objectives are attainable. In 55 bc Orodes II was facing rebellion by his brother, Mithridates III, who had sought Roman assistance. If Crassus had moved then, he could have helped Mithridates and installed a pro-Roman king on the Parthian throne. But Crassus dawdled, and Mithridates was defeated and killed in 54 bc.
- Firm up your allies. Artavasdes of Armenia offered to aid Rome if Crassus would agree to swing north and advance through his kingdom. Crassus declined. Later, during the Roman retreat, Crassus hoped to reach the Armenian highlands and the protection of his supposed ally. But by then, Orodes had invaded Armenia and secured Artavasdes’ allegiance. In fact, Orodes and Artavasdes were watching a play by Euripides when Crassus’ severed head arrived and was tossed onstage.
- Arms work best in combination. The Parthian cataphracts and mounted archers achieved more together than either could alone.
- Don’t present an obvious target. The cataphracts hovered in front of the Roman line, forcing the Romans to maintain a close formation. This made them an easy target for the Parthian archers, who rode around both flanks and subjected the Romans to a deadly fire.
- Keep your forces together. Publius rushed out with his Gallic cavalry to an unsupportable position. Once cut off by the cataphracts, they were beyond help.
- Numbers aren’t everything. Superior weapons, superior tactics, superior logistics (that camel train), psyops (Publius’ head on a spear) and treachery can carry the day, even against 3-to-1 odds.
- Watch your back. Surena won great fame for his victory over the Romans at Carrhae. But Orodes II grew to resent this and had him executed.