Lysimachus, Seleucus, and Ptolemy now divided the empire of Alexander between them. In Egypt the aged Ptolemy had abdicated in 285 in favour of his son by Berenice afterwards known as Ptolemy Philadelphus, and to the exclusion of his eldest son, Ptolemy Ceraunus, by his wife Eurydice. Ptolemy Ceraunus quitted Egypt in disgust, and fled to the court of Lysimachus; and Arsinoe, the wife of Lysimachus, jealous of her stepson Agathocles, the heir apparent to the throne, and desirous of securing the succession for her own children, conspired with Ptolemy Ceraunus against the life of Agathocles. She even procured the consent of Lysimachus to his murder; and after some vain attempts to make away with him by poison, he was flung into prison, where Ptolemy Ceraunus despatched him with his own hand. Lysandra, the mother of Agathocles, fled with the rest of her family to Seleucus, to demand from him protection and vengeance; and Seleucus, induced by the hopes of success, inspired by the discontent and dissensions which so foul an act had excited among the subjects of Lysimachus, espoused her cause. The hostilities which ensued between him and Lysimachus were brought to a termination by the battle of Corupedion, fought near Sardis in 281, in which Lysimachus was defeated and slain. By this victory, Macedonia, and the whole of Alexander's empire, with the exception of Egypt, southern Syria, Cyprus, and part of Phoenicia, fell under the sceptre of Seleucus. That monarch, who had not beheld his native land since he first joined the expedition of Alexander, now crossed the Hellespont to take possession of Macedonia. Ptolemy Ceraunus, who after the battle of Corupedion had thrown himself on the mercy of Seleucus, and had been received with forgiveness and favour, accompanied him on this journey. The murder of Agathocles had not been committed by Ptolemy merely to oblige Arsinoe. He had even then designs upon the supreme power, which he now completed by another crime. As Seleucus stopped to sacrifice at a celebrated altar near Lysimachia in Thrace, Ptolemy treacherously assassinated him by stabbing him in the back (280). After this base and cowardly act, Ptolemy Ceraunus, who gave himself out as the avenger of Lysimachus, was, by one of those movements wholly inexplicable to our modern notions, saluted king by the army; but the Asiatic dominions of Seleucus fell to his son Antiochus, surnamed Soter. The crime of Ptolemy, however, was speedily overtaken by a just punishment. In the very same year his kingdom of Macedonia and Thrace was invaded by an immense host of Celts, and Ptolemy fell at the head of the forces which he led against them. A second invasion of the same barbarians compelled the Greeks to raise a force for their defence, which was intrusted to the command of the Athenian Callippus (B.C. 279). On this occasion the Celts attracted by the report of treasures which were now