The Parthian counterthrust in 52–50 bc under the command of Prince Pacorus (Pakores) was not crowned with success. The Arsacid army did not know how to organize long campaigns or how to lay siege to fortified cities. But soon, civil war in Rome reinforced the position of the Parthians, and Pompey, after being defeated by Caesar, thought of taking refuge among them. It is thought that Orodes, taking advantage of this lull, succeeded in resolving difficulties in the east with the Yuezhiuezhi, even perhaps with the Kushān. In 48 bc, with Pompey dead, Caesar was the absolute master of the Roman world. He was preparing to avenge Crassus’s defeat when he was assassinated in 44 bc. The duty of following through on Caesar’s project fell to Mark Antony. Pacorus, anticipating Antony, crossed into Syria after having concluded an agreement with Quintus Labienus, a Roman commander on the side of Caesar’s assassins who had gone over to the Parthians. The successes of the two armies were startling: Labienus took all of Asia Minor, Pacorus all of Syria and Palestine. For nearly two years all the western provinces of the Achaemenids remained in Parthian hands. In Rome it was rumoured that the Parthians were planning to invade Italy itself. But the successes of the Arsacid armies were as ephemeral as they were remarkable. Disagreement between the two generals weakened their effect. In 39 bc Labienus was conquered by Roman forces under Publius Ventidius and slain. Asia Minor was recovered by the Romans, and the following year the same fate struck Pacorus and his conquests.
Under Orodes II the Parthians had reached the zenith of their power: in the west the Arsacids had for a short time reestablished the empire of the Achaemenids almost in its entirety. Their successes in the east seem to have been equally important. Their capital was moved to Ctesiphon, where a military camp was transformed into a great metropolis, facing Seleucia across the Tigris. At Nisā the city was expanded, the royal palaces were enlarged, and the royal hypogea (catacombs) were enriched with precious pieces of fine Greco-Iranian art.
In 37 bc Orodes was assassinated by his son Phraates IV, who also did away with his brothers and his eldest son. In 36 bc Mark Antony began to carry out the revenge Caesar had planned. He brought his army to Armenia, through which he planned to enter Media and attack Parthia from the north. But cold weather and Phraates’ cavalry combined to force Antony to abandon the fight and return to Syria. In 34 bc he launched another campaign and again suffered heavy losses, and his power struggle with Octavian forced him to abandon his plans for war against the Parthians.
About 30 bc Tiridates II, a pretender to the throne of Parthia supported by Rome, forced Phraates IV to leave Mesopotamia and take refuge with his eastern neighbours, the Scythians, who restored him to power. Driven out, Tiridates took refuge at Rome. He returned again in 26 bc, after which Phraates was able to definitively reestablish his power at the same time that Octavian was inaugurating the imperial period of Roman history. Settlement with Rome
The new stage in the phil-Hellenistic period began about 31 bc, when, after his victory over Mark Antony, Octavian (now Caesar Augustus) was the sole master in Rome. Before that, however, he had already proposed to Phraates an alliance and a treaty ending the war. The Battle of Carrhae and Antony’s defeat had raised Parthia to a major power in the eyes of Rome. Augustus put pressure on Phraates IV through the pretender Tiridates and even tried military intervention. In the end a pact was signed in 20 bc that allowed Roman prisoners and the insignia of the conquered legions to be returned. A new stage began in relations between the two states, marked by the conclusion of a real peace that recognized the Euphrates as a frontier between them. Phraates was dealt with as the sovereign of a great nation. Rome renounced its ambitions in the east, and Augustus inaugurated a policy of respect. The two states could do nothing but profit from the agreement, for a defeat would have been fatal to either power and a victory hazardous. The caravan route to India and China was reopened. Augustus received ambassadors from the many eastern peoples, including the Indo-Scythians and the Sarmatians. The only country in the east where Rome remained active was Armenia.
All obstacles, however, were not necessarily eliminated. There remained the question of Armenia: if it was controlled by Rome, it would be a channel for penetration into Parthia from the north, but if it was controlled by Parthia, it would offer an outlet on the Black Sea, over which Rome asserted its authority. The rivalry of the two powers over this country would remain for centuries a stumbling block to peace.
Toward 10 or 9 bc Phraates sent his four sons and grandsons to Rome, a gesture that was both one of confidence in a “friendly” power and also a guarantee that his throne would pass to his son by Musa, an Italian slave girl given him by Augustus. This son would assassinate his father with his mother’s help and occupy the throne as Phraates V from 2 bc to ad 4 after having married his mother.
The end of the “phil-Hellenistic” period is marked by the clash of the ruling class with foreign influences that had penetrated life in Parthian society. These influences came from Rome and were often introduced by princes of the Arsacid house returning from stays abroad. The short reign of Orodes III (ad 4–6/7) was followed by that of Vonones I (7/8–11), a son of Phraates IV who, because of his Roman habits, was driven out by the Parthian nobility, whose role by that time had become dominant in internal politics and dynastic questions. Vonones’ fall brought about a change in the destinies of the country. The “anti-Hellenistic” period (ad 12–162)
A new and important period in Parthian history, often called “anti-Hellenistic,” embraces a century and a half, from ad 12 to 162. It is characterized by an expansion of the native Parthian culture and an opposition to all things foreign. The weakness of the reigning dynasty opened wide avenues to the nobility to involve themselves in the official existence of the state. They chose the sovereign whose reign opened the first stage in this new period. Artabanus III
The king chosen by the barons to replace Vonones was Artabanus III (reigned 12–38). They were certainly mistaken in believing they would find in him an easy instrument to manipulate. Artabanus was the son of a viceroy of Hyrcania and was Arsacid only on his mother’s side. Under his rule Parthia entered a brilliant but troubled era, one completely dominated by the personality of this violently anti-Roman sovereign who was eager to drive Rome out of Asia. However, after he failed to place his son on the throne of Armenia, for years Artabanus avoided precipitating matters with Rome and dedicated himself to internal reforms, among which centralization was the most important.
The humbling of the great nobles, an enterprise in which he was sustained by the lesser nobles, became necessary. He had to reduce the hereditary privileges the barons had carved out for themselves. It was also necessary to reorganize the states that made up the kingdom. He put princes of his family on the thrones of Mesene, Persis, Elymais, Atropatene—all little states that were governed by men loyal to the throne. But it proved impossible for him to put down a revolt in the eastern possessions, where the Indo-Parthian king Gondophares declared himself independent (c. 19) and took the title “king of kings.”
It is thought that the position taken toward the city-states, about which precise information is lacking, was the reason for the seven-year-long revolt of Seleucia on the Tigris. The fighting there took place between the Greek and Hellenized elements and the Semites, who demanded their right to participate in the autonomy of the city and who supported pretenders against Artabanus III.