The Battle of Tigranocerta (Տիգրանակերտի ճակատամարտը, Tigranakerti Tchakatamartuh) was fought on October 6, 69 BC between the forces of the Roman Republic and the army of the Kingdom of Armenia led by King Tigranes the Great. The Roman force was led by Consul Lucius Licinius Lucullus, and Tigranes was defeated. His capital city of Tigranocerta was lost to Rome as a result.
The battle arose from the Third Mithridatic War being fought between Roman Republic and Mithridates VI of Pontus, whose daughter Cleopatra was married to Tigranes. Mithridates fled to seek shelter with his son-in-law, and Rome invaded the Kingdom of Armenia. Having laid siege to Tigranocerta, the Roman forces fell back behind a nearby river when the large Armenian army approached. Feigning retreat, the Romans crossed at a ford and fell on the right flank of the Armenian army. After the Romans defeated the Armenian cataphracts, the balance of the Armenian army, which was mostly made up of raw levies and peasant troops from Tigranes' extensive empire, panicked and fled, and the Romans won the battle.
This period of Armenian hegemony in the region, however, was coming close to an end with a series of Roman victories in the Roman-Mithirdatic wars that were taking place in the west. Friction between the two had existed for several decades, although it was during the Third Mithridatic War that the Roman armies under Lucius Licinius Lucullus made significant progress against Mithridates, forcing him to take refuge with Tigranes. Lucullus sent an ambassador named Appius Claudius to Antioch to demand that Tigranes surrenders his father-in-law; should he refuse, Armenia would face war with Rome. Tigranes refused Appius Claudius' demands, stating that he would prepare for war against the Republic.
Lucullus was astonished upon hearing this in the year 70, and he began immediately to prepare for an invasion of Armenia. Although he had no legal mandate to authorize such a move, he attempted to justify his invasion by distinguishing as his enemy as Tigranes and not his subjects. In the summer of 69, he marched his troops across Cappodocia and the Euphrates river and entered the Armenian province of Tsopk, where Tigranocerta was located.
Tigranes, who was residing at Tigranocerta in the summer of 69, was not only astonished by the speed of Lucullus' rapid advance into Armenia but by the fact that he had even launched such an operation in the first place. Unable to reconcile with this reality for a certain period of time, he belatedly sent a general named Mithrobarzanes with 2,000 to 3,000 men to slow down Lucullus' advance but his forces were cut to pieces and routed by the 1,600 cavalry led by one of the legates serving under Lucullus, Sextilius. Learning of Mithrobarzanes' defeat, Tigranes entrusted the defense of his namesake city to Mancaeus and left to recruit a fighting force in the Taurus Mountains. Nevertheless, Lucullus' legates were able to disrupt two separate detachments coming to Tigranes aid and even located and engaged the king's forces in a canyon in the Taurus. Lucullus, nevertheless, chose not to pursue Tigranes while he had an unimpeded path towards Tigranocerta; he advanced and began to lay siege to it.
Tigranocerta was still an unfinished city when Lucullus laid to siege it in the late summer of 69. The city was heavily fortified and according to the Greek historian Appian, had towering walls that stood 25 meters high, providing a formidable defense against a prolonged siege. The Roman siege engines that were employed at Tigranocerta were effectively repelled by the defenders by the use of naphtha, making Tigranocerta, according to one scholar, the site of "perhaps the world's first use of chemical warfare.
The loyalty of the city's population was untested: since Tigranes had forcibly removed many of its inhabitants from their native lands and brought them to Tigranocerta, their allegiance to the king was cast into doubt. They soon proved their unreliability: when Tigranes and his army appeared on a hill overlooking the city, the inhabitants "greeted his [Lucullus] appearance with shouts and din, and standing on the walls, threateningly pointed out the Armenians to the Romans.
Appian claims that Lucullus had embarked from Rome with only a single legion; upon entering Anatolia to make war against Mithridates, he added four more legions to his army. The overall size of this force consisted of 30,000 infantry and 1,600 cavalry. Following Mithridates' retreat to Armenia, Appian estimates Lucullus' invading force to be only two legions and 500 horses, although it is highly improbably that he would have undertaken the invasion of Armenia with such a small army. Historian Adrian Sherwin-White places the size of Lucullus' force to 12,000 seasoned legionaries (composed of three legions), and 4,000 provincial cavalry and light infantry. The Roman army was further bolstered by several thousand allied Gallic, Thracian, and Bithynian infantry and cavalry.
Tigranes' army clearly held a numerical superiority over that of Lucullus'. According to Appian, it numbered 250,000 infantry and 50,000 cavalry. Many scholars, however, doubt these figures accurately reflect the true number of Tigranes' numerically superior army and are regarded to be highly inflated. Some historians, most notably Plutarch, wrote that Tigranes considered Lucullus' army to be far too small, and upon seeing it, is quoted to have said that "If they are come as ambassadors, they are too many; if as soldiers, too few, although some have expressed doubt on the veracity of this quote. Tigranes also had in his possession several thousand cataphracts, formidable heavily armored cavalry that were clad in chain mail and often armed with lances, spears or bows.
The two armies converged toward the Batman-Su river slightly to the southwest to Tigranocerta. Tigranes' army was positioned on the east bank of the river while Lucullus, who had left a rear guard to continue the siege of the city, met the Armenian army on the river's west bank. The Armenian army was formed of three sections: a left flank, a center, and a right flank. Two vassal kings from Tigranes' empire led the left and right flanks while Tigranes was with his cataphracts in the center; the rest of his army stood in front of a hill which Lucullus would soon exploit to his advantage. His troops at first attempted to dissuade him from engaging in battle since October 6 marked the day of the disastrous battle of Arausio, where the general Quintus Servilius Caepio and his Roman army were delivered a crushing defeat by the Germanic Cimbri and Teuton tribes. Ignoring his troops' superstitious beliefs, Lucullus is said to have responded, "Verily, I will make this day, too, a lucky one for the Romans. Lucullus marched his men towards the river in a simplex acies formation, making it appear much larger than it really was. He took several of his troops downriver, where the river was the most easiest to ford, and at one moment, Tigranes believed that this move meant Lucullus was withdrawing from the battlefield.
Lucullus had initially decided to make a running charge with his infantry, a Roman military tactic that minimized the amount of time an enemy could utilize its archers and sling infantry prior to close combat engagement. However, he decided against this at the last moment when he realized that the Armenian cataphracts posed the greatest threat to his men, ordering instead a diversionary attack with his Gallic and Thracian cavalry against the cataphracts. With the cataphracts' attention fixated elsewhere, Lucullus formed two cohorts into maniples and then ordered them to ford across the river. His objective was to outflank Tigranes' cataphracts by circling counterclockwise around the hill and attacking them from the rear.
Lucullus personally led the charge on foot and upon reaching the top of the hill, he yelled to his soldiers in an effort to buoy their morale: "The day is ours, the day is ours, my fellow soldiers! With this, he gave special instructions to the cohorts to attack the horses' legs and thighs, since these were the only areas of the cataphracts which were not armored. Lucullus charged downwards along with his cohorts and his orders soon proved fatal: the lumbering cataphracts were caught by surprise and, in their attempts to break free from their attackers, ran against the ranks of their own men as the lines began to collapse.
The infantry, which was also made up of many foreigners, began to break rank and confusion spread to the rest of the body of Tigranes' army. While the king himself took to flight with his baggage train northwards, the entire line of the Armenian army gave way. The casualties suffered by Tigranes' army were immense, with estimates given from as little as 10,000 to as many as 100,000 men. Plutarch says that on the Roman side, "only a hundred were wounded, and only five killed, although such low figures are highly unrealistic.
The battle is highlighted by many historians specifically because Lucullus overcame the numerical odds facing his army. The Italian philosopher Niccolo Machiavelli remarked upon the battle in his book, The Art of War, where he critiqued Tigranes' heavy reliance on his cavalry over his infantry.