[2] The battle arose from the Third Mithridatic War being fought between the Roman Republic and Mithridates VI of Pontus, whose daughter Cleopatra was married to Tigranes.

With his father-in-law and ally securing the empire's western flank, Tigranes was able to conquer territories in Parthia and Mesopotamia and annex the lands of the Levant.

In Syria, he began the construction of the city of Tigranocerta (also written Tigranakert), which he named after himself, and imported a multitude of peoples, including Arabs, Greeks, and Jews, to populate it.

The city soon became the king's headquarters in Syria and flourished as a great centre for Hellenistic culture, complete with theatres, parks and hunting grounds.

Friction between the two had existed for several decades, although it was during the Third Mithridatic War that the Roman armies under 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 surrender his father-in-law; should he refuse, Armenia would face war with Rome.

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.

Learning of Mithrobarzanes' defeat, Tigranes entrusted the defence of his namesake city to Mancaeus and left to recruit a fighting force in the Taurus Mountains.

[5] Lucullus' legates were able to disrupt two separate detachments coming to the aid of Tigranes, and even located and engaged the king's forces in a canyon in the Taurus.

The city was heavily fortified and according to the Greek historian Appian, had thick and towering walls that stood 25 meters high, providing a formidable defence against a prolonged siege.

[14] Historian Adrian Sherwin-White places the size of Lucullus' force at 12,000 veteran legionaries (three understrength legions), and 4,000 provincial cavalry and light infantry.

"[24] Cowan and Hook suggest that Lucullus would have deployed the Romans in a simplex acies, that is to say a single line, so making the frontage of the army as wide as possible as a counter to the cavalry.

[20] He took several of his troops downriver, where the river was the easiest to ford, and at one point, Tigranes believed that this move meant Lucullus was withdrawing from the battlefield.

[30][31] Lucullus charged downhill with his cohorts and his orders soon proved decisive: the lumbering cataphracts were caught by surprise and, in their attempts to break free from their attackers, careered into the ranks of their own men as the lines began to collapse.

[12] The Italian philosopher Niccolò Machiavelli remarked upon the battle in his book, The Art of War, where he criticised Tigranes' heavy reliance on his cavalry over his infantry.