This led Phraates III to put Tigranes the Younger in charge of the Armenian expedition, reinforcing him with some Parthian soldiers.

Tigranes the Younger, however, was ultimately defeated by his father, leading him to desert Phraates III and join the Roman commander Pompey instead.

[6] The Artaxiad king of Armenia, Tigranes the Great (r. 95–55 BC), took advantage of the Parthians' weakness and retook the "seventy valleys" he had previously ceded to Mithridates II.

[8] However, this began to change; in the same year, the Roman commander Lucullus pushed Tigranes out of Syria and Cilicia, forcing him to retreat to Armenia, where Mithridates VI took refuge with him.

[9] Lucullus then marched towards Armenia, where he was likewise successful, forcing Tigranes and Mithridates VI to withdraw to the northern part of the country.

From there they implored Phraates III to aid them in exchange for the lost Parthian lands of Gordyene, Adiabene, and northern Mesopotamia.

A few years earlier (72 BC), Mithridates VI had asked Phraates III's father Sinatruces to join him; he declined, preferring to remain neutral.

[11] At the same time, Phraates III was in correspondence with Lucullus, who proposed an alliance between the two powers, seemingly with the guarantee that he would acknowledge Parthian demands against Tigranes.

[12] Although Lucullus had been successful in his war against the two monarchs initially, their forces remained a threat to the Romans and still possessed the strength to repel him.

[13] Phraates III seemingly made promises to both parties but remained passive to await the outcome of the war.

[14] In 66 BC, Phraates III entered into negotiations with Lucullus' successor Pompey, who possibly offered Roman acknowledgement of Parthian authority over Mesopotamia, Adiabene, and Gordyene in exchange for military aid.

[15] This marriage, which took place in 66/65 BC, gave Phraates III the opportunity to involve himself in the affairs of Armenia, including preventing Pompey from putting Parthian interests in jeopardy.

Initially successful, their efforts were halted by a long siege at Artaxata, which led Phraates III to put Tigranes the Younger in charge of the Armenian expedition, reinforcing him with some Parthian soldiers.

According to Rahim M. Shayegan, it was because he remained an ally of Phraates III, with whom he still conspired with to overthrow Tigranes the Elder, whilst Michał Marciak states it was due to his dispute with Pompey over Sophene's treasury.

[39] In the Parthian era, Iranians used Hellenistic iconography to portray their divine figures,[40][41] thus the eagle can be associated with the Avestan Verethragna, the royal falcon.

[44] With the support of the Suren clan, Orodes II defeated his brother and established himself as the sole ruler of the Parthian Empire in 55 BC.