(Μιθριδάτης) of PERGAMUS, was the son of Menodotus, a citizen of that place, by a daughter of Adobogion, a descendant of the tetrarchs of Galatia, but his mother having had an amour with Mithridates the Great, he was generally looked upon as in reality the son of that monarch. To this supposition the king himself lent some countenance by the care he bestowed on his education, having taken him into his own court and camp, where the young man was trained in all kinds of military exercises and studies. (Strab. xiii. p.625; Hirt. de B. Alex. 78.) His natural abilities, united to his illustrious birth, raised him to a high place in the estimation of his countrymen, and he appears as early as B. C. 64 to have exercised the chief control over the affairs of his native city. (Cic. pro Flacc. 7; Schol. Bob. ad loc.) At a subsequent period he was fortunate enough to obtain the favour and even personal friendship of Caesar, who, at the commencement of the Alexandrian war (B. C. 48), sent him into Syria and Cilicia to raise auxiliary forces. This service he performed with zeal and alacrity, and having assembled a large body of troops advanced by land upon Egypt, and by a sudden attack made himself master of Pelusium, though that important fortress had been strongly garrisoned by Achillas. But he was opposed at the passage of the Nile by the Egyptian army commanded by Ptolemy in person, and compelled to apply to Caesar for assistance. The dictator hastened to his support by sea, and, landing at the mouth of the Nile, united his forces with those of Mithridates, and immediately afterwards totally defeated the Egyptian king in a decisive action which put an end to the war. (Hirt. de B. Alex. 26-32; D. C. 42.41_43; J. AJ 14.8.1_3, B. J. 1.9.3-5.) It is probable that he afterwards accompanied Caesar on his campaign against Pharnaces, as immediately after the defeat of that monarch, Caesar bestowed his kingdom of the Bosporus upon Mithridates, on whom he conferred at the same time the tetrarchy of the Galatians that had been previously held by Deiotarus, to which he had an hereditary claim. (Hirt. de B. Alex. 78; Strab. xiii. p.625; D. C. 42.48; Appian, App. Mith. 121; Cic. Phil. 2.37, de Divin. 2.37.) But the kingdom of the Bosporus still remained to be won, the title being all that it was really in the power of Caesar to bestow, for Asander, who had revolted against Pharnaces and put him to death on his return to his own dominions, was in fact master of the whole country, and Mithridates having soon after attempted to establish himself in his new sovereignty and expel Asander, was defeated and slain. (Strab. l.c. ; D. C. 42.48, 47.26.)