Shortly after 100 BC, King Tigran (Tigranes) I of Armenia founded Tigranocerta as his southern capital and populated it with colonists forceably relocated from Cappadocia and other conquered territories. In 69 BC, after defeating Mithridates of Pontus to the north, a Roman army under Lucius Licinus Lucullus invaded Armenia to punish Mithridates' erstwhile allies. Tigran abandoned Tigranocerta and began to gather an army at Taurus. Despite vigorous Roman attacks designed to disrupt the muster, Tigran soon had gathered a large force of Armenians and allied contingents. According to Plutarch,
"He had twenty thousand archers and slingers, fifty-five thousand horse, of which seventeen thousand were in complete armour, as Lucullus wrote to the senate, a hundred and fifty thousand heavy-armed men, drawn up partly into cohorts, partly into phalanxes, besides various divisions of men appointed to make roads and lay bridges, to drain off waters and cut wood, and to perform other necessary services, to the number of thirty-five thousand, who, being quartered behind the army, added to its strength, and made it the more formidable to behold."
Undaunted, Lucius Licinus Lucullus invested Tigranocerta and pressed the seige. Goaded into action, Tigran advanced, confident of easy victory due to the disproportionate size of his forces. As Tigran's host approached, Lucullus then split his army, leaving 6,000 foot under Murena to maintain the seige and marching forth with a force of 12,000 infantry and 5,000 cavalry to block Tigran's host. They formed a line along a deep river facing the advancing Armenians, who deployed opposite them across the river, with a large force of cataphracts forming their right wing.
Rather than hold the river against a crossing, the Romans formed a march column and filed off to the left, as if in retreat. Coming to a ford at a bend in the river, they then crossed over and quickly fell on Tigran's right flank, with Lucullus personally leading the way with sword in hand. Taken by surprise, Tigran and his generals hurriedly rushed to adjust their battle lines. Plutarch describes the subsequent battle as follows:
"Having so said, he bade them take courage, passed over the river, and himself first of all led them against the enemy, clad in a coat of mail, with shining steel scales and a fringed mantle; and his sword might already be seen out of the scabbard, as if to signify that they must without delay come to a hand-to-hand combat with an enemy whose skill was in distant fighting, and by the speed of their advance curtail the space that exposed them to the archery. But when he saw the heavy-armed horse, the flower of the army, drawn up under a hill, on the top of which was a broad and open plain about four furlongs distant, and of no very difficult or troublesome access, he commanded his Thracian and Galatian horse to fall upon their flank, and beat down their lances with their swords. The only defence of these horsemen-at-arms are their lances; they have nothing else that they can use to protect themselves or annoy their enemy, on account of the weight and stiffness of their armour, with which they are, as it were, built up.
"He himself, with two cohorts, made to the mountain, the soldiers briskly following, when they saw him in arms afoot first toiling and climbing up. Being on the top and standing in an open place, with a loud voice he cried out, "We have overcome, we have overcome, fellow-soldiers!" And having so said, he marched against the armed horsemen, commanding his men not to throw their javelins, but coming up hand-to-hand with the enemy, to hack their shins and thighs, which parts alone were unguarded in these heavy-armed horsemen. But there was no need of this way of fighting, for they stood not to receive the Romans, but with great clamour and worse flight they and their heavy horses threw themselves upon the ranks of the foot, before ever these could so much as begin the fight, insomuch that without a wound or bloodshed, so many thousands were overthrown. The greatest slaughter was made in the flight, or rather in the endeavouring to fly away, which they could not well do by reason of the depth and closeness of their own ranks, which hindered them."
With the Armenian cataphracts all destroyed or driven off, the rest of Tigran's army of light foot took flight, closely pursued by the Romans. According to Plutarch, "above a hundred thousand foot were lost, and that of the horse but very few escaped at all. Of the Romans, a hundred were wounded and five killed
