=22.= The ambition of Antigonus now began to alarm his colleagues, for he was evidently not to be satisfied with less than the entire dominion of Alexander. He gave away the eastern satrapies according to his pleasure. From Babylonia he drove Seleu´cus, who took refuge with Ptolemy in Egypt, and formed a league with Cassander, Lysim´achus, and Asander. A war of four years followed (B. C. 315-311), which resulted in the re-establishment of Seleucus in Babylon and the East, while Antigonus gained power in Greece, Syria, and Asia Minor. The peace of B. C. 311 provided for the independence of the Greek cities, but allowed each general to keep what he had gained, and left Cassander regent of Macedonia until Alexander IV. should be of age. It was probably understood between the contracting parties that this last event was never to occur. The young king and his mother were murdered, by order of Cassander. =23.= At the end of a year, Ptolemy broke the peace, on the pretense that Antigonus had not liberated the Greek cities of Asia Minor. He was opposed in Cilicia by Deme´trius, son of Antigonus, who gained in this war the title of _Po´liorce´tes_, the Besieger. Ptolemy, entering Greece, seized Sicyon and Corinth, and aimed to marry Cleopatra, the last survivor of the royal house of Macedon; but the princess was assassinated, by order of Cassander, B. C. 308. Demetrius now arriving with a fleet to the relief of Athens, Ptolemy withdrew to Cyprus, and gained possession of the island. A great battle followed off Salamis, one of the most severe in the world’s history. Ptolemy was defeated, with the loss of all but eight of his ships, leaving 17,000 prisoners in the hands of the enemy. =24.= The five principal generals now assumed the kingly title. Demetrius spent a year in the siege of Rhodes, which, by its brave and memorable defense, secured the privileges of a neutral in the remaining years of the war. Returning to Greece, he assembled a congress at Corinth, which conferred upon him the titles formerly bestowed on Philip and Alexander, and then marched northward against the regent, or, rather, king of Macedon. Alarmed at his endangered position, Cassander stirred up his allies to invade Asia Minor.