The Third Mithridatic War (73–63 BC), the last and longest of the three Mithridatic Wars, was fought between Mithridates VI of Pontus and the Roman Republic. Both sides were joined by a great number of allies, dragging the entire Eastern Mediterranean and large parts of Asia (Asia Minor, Greater Armenia, northern Mesopotamia and the Levant) into the war. The conflict ended in defeat for Mithridates; it ended the Pontic Kingdom and the Seleucid Empire (by then a rump state), and also resulted in the Kingdom of Armenia becoming an allied client state of Rome.
Background
In 120 BC, Mithridates V, the king of Pontus was poisoned by unknown figures.Mayor, The Poison King: the life and legend of Mithradates, Rome's deadliest enemy p. 68 The conspirators were probably working for his wife Laodice.Philip Matyzak, Mithridates the Great, Rome's Indomitable Enemy, p. 6 In his will Mithridates V left the kingdom to the joint rule of Laodice, Mithridates VI and Mithridates Chrestus. Both of her sons were underage and Laodice retained all power as regent.Mayor, The Poison King: the life and legend of Mithradates, Rome's deadliest enemy p. 69 Laodice in her regency favored her second son (Chrestus was probably more pliable). During her regency 120–116 BC (perhaps even 113 BC), Mithridates VI escaped the court of his mother and went into hiding. He returned between 116 and 113 BC and was able to remove his mother and his brother from the Pontic throne, thus becoming the sole ruler of Pontus.Mayor, The Poison King: the life and legend of Mithradates, Rome's deadliest enemy p. 394
Mithridates entertained ambitions of making his state the dominant power in the east of Asia Minor and the Black Sea region. He first subjugated Colchis, a region east of the Black Sea, and prior to 164 BC, an independent kingdom. He then clashed for supremacy on the Pontic steppe with the Scythian King Palacus. The most important cities and people of the Crimea, the Tauric Chersonesus and the Bosporan Kingdom readily surrendered their independence in return for Mithridates' protection against the Scythians, their ancient enemies. The Scythians and their allies the Rhoxolanoi suffered heavy losses at the hands of the Pontic general Diophantus and accepted Mithridates as their overlord.Philip Matyzak, Mithridates the Great, Rome's Indomitable Enemy, pp. 13–18
The young king then turned his attention to Asia Minor, where Roman power was on the rise. He contrived to partition Paphlagonia and Galatia with King Nicomedes III of Bithynia. Yet it soon became clear to Mithridates that Nicomedes was steering his country into an anti-Pontic alliance with the expanding Roman Republic. When Mithridates fell out with Nicomedes over control of Cappadocia, and defeated him in a series of battles, the latter was constrained to openly enlist the assistance of Rome. The Romans twice interfered in the conflict on behalf of Nicomedes (95–92 BC), leaving Mithridates, should he wish to continue the expansion of his kingdom, with little choice other than to engage in a future Roman-Pontic war. By this time Mithridates had resolved to expel the Romans from Asia.Philip Matyzak, Mithridates the Great, Rome's Indomitable Enemy, pp. 19–24
The next ruler of Bithynia, Nicomedes IV of Bithynia, was a figurehead manipulated by the Romans. Mithridates plotted to overthrow him, but his attempts failed and Nicomedes IV, instigated by his Roman advisors, declared war on Pontus. Rome itself was involved in the Social War, a civil war with its Italian allies. Thus, in all of Roman Asia Province there were few Roman troops available. The Romans therefore mustered a great number of Asian levies and combined with Nicomedes' army they invaded Mithridates' kingdom in 89 BC. Mithridates won a decisive victory, scattering the Roman-led forces. His victorious forces were welcomed throughout Asia Minor. The following year, 88 BC, Mithridates orchestrated a massacre of Roman and Italian settlers remaining in several Anatolian cities, essentially wiping out the Roman presence in the region. 80,000 people are said to have perished in this massacre. The episode is known as the Asiatic Vespers.Philip Matyzak, Mithridates the Great, Rome's Indomitable Enemy, pp. 25–47
The Romans responded by organising a large invasion force (this time sending their own legions) to defeat him and remove him from power. The First Mithridatic War, fought between 88 BC and 84 BC, saw Lucius Cornelius Sulla force Mithridates out of Greece proper. After being victorious in several battles Sulla, being declared an outlaw by his political opponents in Rome, hurriedly concluded peace talks with Mithridates. As Sulla returned to Italy Lucius Licinius Murena was left in charge of Roman forces in Anatolia. The lenient peace treaty, which was never ratified by the Senate, allowed Mithridates VI to restore his forces. Murena attacked Mithridates in 83 BC, provoking the Second Mithridatic War from 83 BC to 81 BC. Mithridates defeated Murena's two green legions at the Battle of Halys in 82 BC before peace was again declared by treaty.Philip Matyzak, Mithridates the Great, Rome's Indomitable Enemy, pp. 57–100
Prelude The period between the Second and Third wars of Rome and the Pontic Kingdom (81–75 BC) is discussed under the Kingdom of Pontus. There it can be seen how the long piracy wars were a development out of the First Mithridatic War and especially of the alliance between Mithridates VI and Sertorius, which in joining those two threats into a unity much larger than its parts had the serious potential of overturning Roman power. The immediate cause of the Third War was the bequest to Rome by King Nicomedes IV of Bithynia of his kingdom upon his death (74 BC). Mithridates, who had been rebuilding his forces, launched an invasion of Bithynia.Philip Matyzak, Mithridates the Great, Rome's Indomitable Enemy, pp. 101–102
Forces and initial deployments, 74–73 BC Having launched an attack at the same time as a revolt by Sertorius swept through the Spanish provinces, Mithridates was initially virtually unopposed. The Senate responded by sending the consuls Lucius Licinius Lucullus and Marcus Aurelius Cotta to deal with the Pontic threat. The only other possible general for such an important command, Pompey, was in Hispania to help Metellus Pius crush the revolt led by Sertorius. Lucullus was sent to govern Cilicia and Cotta to Bithynia.Anthon, Charles & Smith, William, A New Classical Dictionary of Greek and Roman Biography, Mythology and Geography, 1860, p. 226 According to Appian and Plutarch Lucullus had 30,000 infantry and 1,600–2,500 cavalry while Mithridates was rumoured to have as many as 300,000 men in his force.Appian, Mithridatica, XI.72; Plutarch, Life of Lucullus, 8.
The original plan was that Cotta should tie down Mithridates' fleet, while Lucullus attacked by land. Cotta was therefore ordered to station his fleet at Chalcedon, while Lucullus marched through Phrygia with the intention of invading Pontus. Lucullus had not advanced far when news came through that Mithridates had made a rapid march westward, attacked and defeated Cotta at the Battle of Chalcedon, and forced him to flee behind the walls of Chalcedon. Sixty-four Roman ships had been captured or burnt, and Cotta had lost three thousand men.Holmes, T. Rice, The Roman Republic and the Founder of the Empire, Vol. I, 1923, p. 180Appian Mithridates. 71; Plutarch. Lucullus. 8 There Cotta was forced to remain until Lucullus could come to his rescue.T. Robert S. Broughton, The Magistrates of the Roman Republic, Vol II (1952), p. 99
Mithridates's defeat in western Asia, 73–72 BC Having made his way to Nicomedia, Cotta watched in frustration as Mithridates marched on taking Nicaea, Lampsacus, Nicomedia and Apameia, all major cities in the region. Only nearby Cyzicus held to the Roman cause, probably because many of its citizens (serving in Cotta's army as auxiliaries) had died fighting against Mithridates at Chalcedon. The Pontic army marched on Cyzicus and began a siege.Philip Matyszak, Mithridates the Great, Rome's indomitable Enemy, pp. 106–113; Plutarch Life of Lucullus, 8.
Lucullus was camped somewhere along the Sangarius river in Bithynia when he received news of Cotta's defeat. His soldiers urged him to leave Cotta to his own folly and march on undefended Pontus with its rich potential for loot. Lucullus ignored them and headed toward Chalcedon. Marcus Marius, a Roman rebel cooperating with Mithridates, blocked and confronted him. They faced off at Otroea near Nicaea (present-day Iznik).Keaveney, Lucullus, p. 77. Although Lucullus commanded 30,000 infantry and 2,500 cavalry, he was daunted by the size of the opposing army and reluctant to engage. The arrival of an omen, as reported by Plutarch, was thus fortuitous:Plutarch, Lucullus 8.
No battle occurred. For Marius, delay posed a logistical problem. He had only a few days of supplies for his troops. Lucullus learned of the shortage through prisoner interrogations and decided to wait him out. Marius was forced to move on without the fight he had sought.
Siege of Cyzicus
While Mithridates was besieging Cyzicus, Lucullus and his army arrived; the Romans, with the help of some turncoats, were able to establish a counter-siege, trapping Mithridates' army on the Cyzicus peninsula. During the siege Mithridates sent his cavalry away, with the sick and the wounded, but they were ambushed and slaughtered at the river Rhyndacus. In the middle of a snowstorm, Lucullus met these forces with ten cohorts and attacked them in mid-crossing on both sides of the river. Plutarch and Appian record 15,000 men and 6,000 horses as being captured during the battle.Lee Fratantuono, Lucullus, p. 60; Philip Matyszak, Mithridates the Great, p. 112. The disaster at the Rhyndacus combined with the famine and a plague which had struck his main army forced Mithridates to completely abandon his position, sailing north while his army marched overland. Lucullus pursued the army and defeated them at the confluence of the Aesepus and Granicus Rivers, slaughtering many (20,000 were killed while crossing the river Granicus). Eventually, of the 300,000 who had set out for Bithynia, only 20,000 effective troops remained. The siege of Cyzicus and the subsequent retreat could be considered an unmitigated disaster.Philip Matyszak, Mithridates the Great, Rome's Indomitable Enemy, pp. 112–113.
Naval campaign Marcus Marius, having survived the Cyzicus campaign, had taken to the sea. Along with Mithridates's admirals Alexandros the Paphlagonian and Dionysios Eunuchos ("the Eunuch"), he was placed in joint command of 50 ships and 10,000 handpicked men, among them, in the words of Mommsen, "the flower of the Roman emigrants."Theodor Mommsen, The History of Rome, vol. 4, p. 329. Their intention seems to have been to sail east into the Aegean, but Lucullus mounted an attack against them. He captured a detachment of 13 ships between the island of Tenedos and the mainland harbor of the Achaeans. The main Pontic force, however, had drawn their ships to shore at a site difficult of approach, the small island of Neae between Lemnos and Scyros; Lucullus then sent infantry by land across Neae to their rear, killing many and forcing the rest back to sea.Keaveney, Lucullus, p. 85. Lucullus sunk or captured 32 ships of the royal fleet provided by Mithradates and additional transport vessels. Dionysios committed suicide, but Alexandros was captured and held for display in Lucullus's anticipated triumph. Among the dead were a number of men who had been on Sulla's proscription lists. Marius at first escaped, possibly from a sinking ship, since he was later found ashore taking refuge in a cave.Orosius 6.2.21–22.