PHRAATES III., surnamed Θεός
(Phlegon, l.c.), the son of the preceding. Mithridates of Pontus and
Tigranes applied to Phraates for assistance in their war against the Romans, although Phraates
was at enmity with Tigranes, because he had deprived the Parthian empire of Nisibis and part
of Mesopotamia. Among the fragments of Sallust (Hist. lib. iv.) we have a
letter purporting to be written by Mithridates to Phraates on this occasion. Lucullus, as soon
as he heard of this embassy, also sent one to Phraates, who dismissed both with fair promises,
but according to Dio Cassius, concluded an alliance with the Romans. He did not however send
any assistance to the Romans, and eventually remained neutral. (Memnon, apud Phot. Cod. 224, p. 239, ed. Bekker ; D. C. 35.1, 3, comp. 6; Appian, App. Mith. 87 ;
Plut. Luc. 30.) When Pompey succeeded Lucullus in the command,
B. C. 66, he renewed the alliance with Phraates, to whose court
meantime the youngest son of Tigranes, also called Tigranes, had fled after the murder of his
two brothers by their father. Phraates gave the young Tigranes his daughter in marriage, and
was induced by his son-in-law to invade Armenia. He advanced as far as Artaxata, and then
returned to Parthia, leaving his son-in-law to besiege the city. As soon as he had left
Armenia, Tigranes attacked his son and defeated him in battle. The young Tigranes then fled to
his grandfather Mithridates, and afterwards to Pompey, when he found the former was unable to
assist him. The young Tigranes conducted Pompey against his father, who surrendered on his
approach. Pompey then attempted to reconcile the father and the son, and promised the latter
the sovereignty of Sophanene; but as he shortly after offended Pompey, he was thrown into
chains, and reserved for his triumph. When Phraates heard of this, he sent to the Roman
general to demand the young man as his son-in-law, and to propose that the Euphrates should be
the boundary between the Roman and Parthian dominions. But Pompey merely replied, that
Tigranes was nearer to his father than his father-in-law, and that he would determine the
boundary in accordance with what was just. (D. C. 36.28, 34_36; Plut.
Pomp. 33; Appian, App. Syr. 104, 105.) Matters now
began to assume a threatening aspect between Phraates and Pompey, who had deeply injured the
former by refusing to give him his usual title of "king of kings." But although Phraates
marched into Armenia, and sent ambassadors to Pompey to bring many charges against him, and
Tigranes, the Armenian king, implored Pompey's assistance, the Roman general
judged it more prudent not to enter into war with the Parthians, alleging as reasons for
declining to do so, that the Roman people had not assigned him this duty, and that Mithridates
was still in arms. (D. C. 37.6, 7;
Plut. Pomp. 38, 39.) Phraates
was murdered soon afterwards by his two sons, Mithridates and Orodes. (D. C. 39.56.)