Crassus one of the most powerful politicians in the era of corruption, Marcus Licinius Crassus (115-53 B.C.), not surprisingly was also one of the richest Roman. Born into a wealthy family, he acquired his riches, according to Plutarch, through "fire and rapine." Crassus became so powerful that he financed the army that put down the slave revolt led by Spartacus.
Marcus Crassus decided to invade Parthia with seven legions and succeeded in capturing a number of border cities. In 53 BC, Crassus crossed the Euphrates in search of the military glory that had so far eluded him in his successful career. His goal was the Parthian capital of Seleucia but, as he advanced, Parthian mounted troops enveloped the large but cumbersome Roman army in the desert, using sustained archery to weaken and wear down their opponents.
As the Roman force advanced further into Parthia they met up with the Parthian army, all cavalry, mostly horse archers with around a thousand heavily armoured cataphracts in support. The Battle of Carrhae was fought in June 53 BC.
Forces sent to drive the horse archers away were surrounded by Parthians and destroyed. With more than 20.000 soldiers killed (Crassus among them) and another 10.000 legionaries taken into captivity by the Parthian cavalry, as a result of the Battle of Carrhae . Only 6,000 Romans managed to fight their way out of the situation.
The battle of Carrhae exposed the art of Parthian warfare, essentially based on the cooperative actions of two cavalry branches: the lightly armed regiments of highly skilled mounted bowmen, known as the ‘pelatai’, and the squads of heavy armed horsemen called the ‘cataphracti’, together capable of inflicting devastating damage to the enemy.
The outcome of the 53 B.C. confrontation had also signalized the need of improving the overall range of battle tactics employed by the Romans, though it does not seem to have had a decisive influence on the overall structure of the imperial army as such.
Battle of Carrhae in 53 BC