2. The younger son of Alexander Jannaeus and Alexandra. (J. AJ 13.16.1; Bell. Jud. 1. 5.1.) During the nine years of his mother's reign he set himself against the party of the Pharisees, whose influence she had restored; and after her death, B. C. 70, he made war against his eldest brother Hyrcanus, and obtained from him the resignation of the crown and the high-priesthood, chiefly through the aid of his father's friends, whom Alexandra had placed in the several fortresses of the country to save them from the vengeance of the Pharisees. (J. AJ 13.16, 14.1.2; Bell. Jud. 1.5, 6.1.) In B. C. 65 Judaea was invaded by Aretas, king of Arabia Petraea, with whom, at the instigation of Antipater the Idumaean, Hyrcanus had taken refuge. By him Aristobulus was defeated in a battle and besieged in Jerusalem but Aretas was obliged to raise the siege by Scaurus and Gabinius, Pompey's lieutenants, whose intervention Aristobulus had purchased. (J. AJ 14.2, 3.2; Bell. Jud. 1.6. §§ 2, 3.) In B. C. 63, he pleaded his cause before Pompey at Damascus, but, finding him disposed to favour Hyrcanus, he returned to Judaea and prepared for war. On Pompey's approach, Aristobulus, who had fled to the fortress of Alexandreion, was persuaded to obey his summons and appear before him; and, being compelled to sign an order for the surrender of his garrisons, he withdrew in impotent discontent to Jerusalem. Pompey still advanced, and Aristobulus again met him and made submission; but, his friends in the city refusing to perform the terms, Pompey besieged and took Jerusalem, and carried away Aristobulus and his children as prisoners. (J. AJ 14.3, 4; Bell. Jud. 1.6, 7; Plut. Pomp. cc. 39, 45; Strab. xvi. p.762; D. C. 37.15, 16.) Appian (Bell. Mith. 100.117) erroneously represents him as having been put to death immediately after Pompey's triumph. In B. C. 57, he escaped from his confinement at Rome with his son Antigonus, and, returning to Judaea, was joined by large numbers of his countrymen and renewed the war; but he was besieged and taken at Machaerus, the fortifications of which he was attempting to restore, and was sent back to Rome by Gabinius. (J. AJ 14.6.1; Bell. Jud. 1. 8.6; Plut. Ant. 100.3; D. C. 39.56.) In B. C. 49, he was again released by Julius Caesar, who sent him into Judaea to forward his interests there; he was, however, poisoned on the way by some of Pompey's party. (J. AJ 14.7.4; Bell. Jud. 1.9.1; D. C. 41.18.)