son Pacorus (Pacorus I) was also seemingly the result of a union with a princess from the peripheries of eastern Parthia. Struggle for the Parthian throne In 57 BC, Orodes and his elder brother Mithridates IV murdered Phraates III. Mithridates IV was at first supported by Orodes, however, this was short-lived. The two brothers quickly fell out, and Orodes revolted with the support of the Suren clan, as well as probably the Scythians of Sakastan. They both assumed the title of King of Kings to demonstrate their claims of superiority over each other. This changed the meaning of the title; originally being used as a symbol of political dominance over other realms, the title became known as a symbol of power and legitimacy for contenders in a royal family. Mithridates IV was forced to flee to Roman Syria. He took refuge with Aulus Gabinius, the Roman proconsul and governor of Syria. Mithridates IV then returned to invade Parthia with Gabinius in support. The Roman proconsul marched with Mithridates IV to the Euphrates, but turned back to restore another ruler, Ptolemy XII Auletes of Egypt, to his throne. Despite losing his Roman support, Mithridates IV advanced into Mesopotamia and managed to conquer Babylonia. He ousted Orodes and briefly restored his reign as king in 55 BC, minting coins in Seleucia until 54 BC. However, king Mithridates IV was besieged by Orodes' Surenid general, Surena, in Seleucia, and after a prolonged resistance, offered battle to Orodes' forces and was defeated. Mithridates IV was afterwards executed in 54 BC by Orodes. Orodes was crowned by Surena, as was the hereditary right of his clan. War with Crassus Around the same time, Marcus Licinius Crassus, one of the Roman triumvirs, who was now proconsul of Syria, had been preparing to invade the Parthian realm in belated support of Mithridates IV. Orodes' emissaries had initially attempted to convince Crassus to abandon his expedition, which the latter replied by saying he would give an answer in Seleucia. The eldest Parthian emissary, Vagises, showed the palm of his hand, stating "Hair will grow here before you see Seleucia." The Artaxiad king of Armenia, Artavasdes II (), who was an ally of Rome, advised Crassus to take a route through Armenia to avoid the desert and offered him reinforcements of a further 10,000 cavalry and 30,000 infantry. His reasoning was that the Parthian cavalry would be less potent