II launched an attack on Ptolemaic outposts in Asia. Most of the information about the Second Syrian War has been lost. It is clear that Antigonus' fleet defeated Ptolemy's at the Battle of Cos in 261 BC, diminishing Ptolemaic naval power. Ptolemy appears to have lost ground in Cilicia, Pamphylia, and Ionia, while Antiochus regained Miletus and Ephesus. Macedon's involvement in the war ceased when Antigonus became preoccupied by the rebellion of Corinth and Chalcis in 253 BC, possibly instigated by Ptolemy, as well as an increase in enemy activity along Macedon's northern frontier. The war was concluded around 253 BC with the marriage of Antiochus to Ptolemy's daughter, Berenice Syra. Antiochus repudiated his previous wife, Laodice, and turned over substantial domain to her. He died in Ephesus in 246 BC, poisoned by Laodice according to some sources. Ptolemy II died in the same year. Third Syrian War (246–241 BC) Also known as the Laodicean War, the Third Syrian War began with one of the many succession crises that plagued the Hellenistic states. Antiochus II left two ambitious mothers, his repudiated wife Laodice and Ptolemy II's daughter Berenice Syra, in a competition to put their respective sons on the throne. Laodice claimed that Antiochus had named her son heir while on his deathbed, but Berenice argued that her newly born son was the legitimate heir. Berenice asked her brother Ptolemy III, the new Ptolemaic king, to come to Antioch and help place her son on the throne. When Ptolemy arrived, Berenice and her child had been assassinated. Ptolemy declared war on Laodice's newly crowned son, Seleucus II, in 246 BC, and campaigned with great success (his forces possibly being commanded by Xanthippus of Sparta, aka Xanthippus of Carthage, the mercenary general responsible for defeating a Roman army at Tunis/Bagrades in 255 BC). He won major victories over Seleucus in Syria and Anatolia, briefly occupied Antioch and, as a recent cuneiform discovery proves, even reached Babylon. These victories were marred by the loss of the Cyclades to Antigonus Gonatas in the Battle of Andros. Seleucus had his own difficulties. His domineering mother asked him to grant co-regency to his younger brother, Antiochus Hierax, as well as rule over Seleucid territories in Anatolia. Antiochus promptly declared independence, undermining Seleucus' efforts to defend against Ptolemy. In exchange for a peace in 241 BC, Ptolemy was awarded new territories on the northern coast of