Aratus, the somewhat melodramatic hero of the Achæan league, on mastering his native city Sicyon by a coup d'état, not only chose to accept a subsidy from Philadelphus rather than from himself, but added Sicyon to the neighboring ethnos of the Achæans. And almost immediately thereafter Ptolemy struck a second blow which made the first of importance. In 250 B.C. Alexander, Antigonus's nephew and chief lieutenant in Greece, egged on by Egypt doubtless, revolted and set himself up as an independent monarch, with Corinth and Calchis, which he had held for his uncle, and the Macedonian fleet of which these were the naval stations, as his basis for action. He at once allied himself with the Achæans and forced Argos and Athens to pay him tribute (before 250-249 B.C.). This rebellion paralyzed the naval power of Antigonus. It was doubtless precipitated by the disloyalty of Antiochus II to Macedon; for that monarch (now, in or before 249 B.C.) broke faith with Antigonus and allied himself with Egypt, retaining the conquests he had made during the war and receiving in marriage Berenice, the only daughter of Philadelphus, whose intrinsic worth was augmented by an enormous dowry. This base and, as it proved, foolish action freed Ptolemy to devote all his energies to the war with Macedon. The fleet of Egypt once more mastered the Ægean and regained control of the league of the Islanders (249 B.C.). Simultaneously, the pro-Egyptian party in Cyrene slew the fair Demetrius, and by the marriage of their young queen Berenice to Philadelphus's heir, effected the reunion of the two kingdoms, which had been estranged since the revolt of Berenice's father, Magas, in 274 B.C.[126] The triumph of Ptolemy was complete, and when his daughter promptly bore to her Seleucid husband a son, who by the marriage stipulation was to be his heir, the future of the Ptolemies seemed bright indeed.