Since the disaster of Carrhae in the last times of the ancient Republic, the eastern frontier was become one of the major preoccupations of Roma.
In this perspective, Augustus Caesar had set up a system of client kingdoms in this frontier, to act as buffers between the Romans and the Parthians.
The kingdom of Armenia was surely the most important of these ones. Its control was crucial.
After the fall of the Artaxiad dynasty, there was a succession of pro-roman and pro-parthian kings.
In 787, the Parthians had imposed their candidate, Arsaces, on the armenian throne to succeed to Artaxias III, but Tiberius Caesar, unwilling to abandon Armenia ordered the poisonning of the so-called usurper. Shortly after, the Iberians driven by the Romans to invade Armenia. Thus, the prince Mithridates, who belonged as the rest of his family to an iberian branch of the former Artaxiad dynasty, was crowned king.
But soon, King Artabanus II of Parthia tried to impose a second of his sons, the prince Orodes, as king.
However, he was was overthrown by pro-roman magnates who crowned Phraates VI, son of the former king Phraates IV. But shortly after, this one fell ill and died. Supported by a roman army under Lucius Vitellius, the prince Tiridates III, a grandson of Phraates IV, took the succession.
But this king, appearing to be almost a puppet of Roma, couldn't manage to maintain himself. Profiting of this, the deposed king Artabanus levied an army of scythian mercenaries in Hyrcania then retook power.
But still unable to wage a war against Roma, he had to recognize Mithridates of Iberia as legitimate king of Armenia.
Although this was a great victory, the situation in Armenia was still far from be definitively settled.
Thus, in 804, fearing the ambition of his son, the king Pharasmanes Ist of Iberia convinced him to invade Armenia and take the throne for himself.
Rhadamistus quickly overran the Armenians. King Mithridates, refugee in the fortress of Gorneas, was betrayed by the roman garrison which had been bribed by his nephew and surrendered, only to be executed.
Claudius Caesar, desiring to avoid provoking the Parthians, demanded only nominally that the Iberians withdraw. An incursion from Cappadocia was of course led, but an expedition from Syria was cancelled to prevent the war.
But the year after, the events took a new turn which will force the Romans to intervene directly.
Taking the opportunity, the parthian king Vologases invaded Armenia and put his brother Tiridates on the throne. Nevertheless, in winter, the Parthians are victim of epidemics and the new of the revolt of the prince Vardanes drove them to leave, what permitted to Rhadamistus to retake advantage.
However, his tyrannic behaviour caused a rebellion and less than two years after,he was forced to flee at his father's court where he was put to death. Tiridates was then recalled to the throne by the Armenians.
At the same time, Claudius Caesar prepared the war. Indeed, by invading Armenia, Vologases had broken a treaty signed with Roma seventy years earlier which accorded to the Romans the right to appoint the armenian kings. Forced to react, the Princeps sent in 808 one of his better generals, Gnaeus Domitius Corbulo in Oriens with the control of Cappadocia and Galatia to organize the offensive.
During more than two years, he trained his troops in the eastern anatolian mountains, acclimatizing them to the snows of Armenia.
In the diplomatic scene, however, none of the attempts from the Princeps did succeeded.
So in 811, the war broke out.
Occupied by nomadic incursions in his eastern provinces and a revolt in Hyrcania, the king Vologases was unable to support his brother. So, with three legions and a great number of auxiliaries given by client kings of Pontus, Armenia Minor, Iberia, Sophene and Commagene, Corbulo entered in Armenia. At first, the Romans advanced unopposed as the king Tiridates wanted avoid an open battle.
Although harassed, they arrived before the walls of Artaxata, one of the two armenian capitals. Forced to do battle to not lose face in the eyes of his subjects, Tiridates was defeated.
Then, Corbulo marched south, towards Tigranocerta, Armenia's second capital. After an exhausting march through the harsh and dry terrain of northern Mesopotamia.
Tigranocerta was quickly taken.
Indeed, it seems that during the march, a plot to muder Corbulo was uncovered and several armenian nobles, falsely rallied to Roma, were executed. The Romans, once arrived to their goal launched the heads in the town, heads which are said to have landed right where the city council was assembled; thus, the town is said to have surrendered.
Now in control of Armenia, the Romans crowned their own candidate on the throne, Tigranes VI, the last descendant of the former cappadocian royal house.
Thereafter, they left the country, letting only some thousands of men to protect it.
The situation seemed settled but two years later, Tigranes VI launched an attack upon Adiabene, theorically a vassal of Armenia but de facto a parthian vassal. Reluctant before to attack again Armenia bacause of the roman success, King Vologases decided to counter-attack.
In 815, after having made peace with the Hyrcanians, he attacked quickly Tigranocerta but, having failed to take the town by assault, he was forced to besiege the town.
Corbulo, become legate of Syria, attempted to convince the Parthians to leave Armenia, but the negociations failed and the war resumed.
Fearing to see Syria invaded, he requested from Roma a separate commander for the armenian front. Lucius Caesennius Paetus, consul of the previous year, was thus sent.
Although Corbulo made progress by establishing a bridgehead on the parthian bank of the Euphrates, the situation in north was a disaster.
Indeed, with the arrival of Paetus, the discipline became low. What's more, the new commander made a great error by dispersing his troops. This led to the battle of Rhandeia where two legions were almost annihilated by King Vologases.
Unfortunately for the Parthians, far to lower the will of the Romans, this setback drove Claudius Caesar to give exceptionnal powers and reinforcements to general Corbulo.
So, by spring 816, he was ready to launch an other offensive which will never come.
Indeed, aware of the abilities of Corbulo as general and of the size of its army, the Parthians accepted to negociate a peace. They met at Rhandeia.
In the end, Tiridates accepted to travel to Roma and seek confirmation of his crown from the Princeps.
Thus ended the war.
