One Berenice had arrived in Egypt after the death of her first husband in the retinue of Eurydice, Ptolemy's second wife and queen, whom he had married as part of a political agreement with her father, Antipater of Macedonia.

Ptolemy in about 317 makes Berenice his third wife.

Ptolemy, adhering to a defensive foreign policy, has secured Egypt against external enemies and expanded it by means of directly controlled foreign possessions and hegemonic administrations.

He has not, however, neglected to devote attention to the internal organization of the country and to provide for a successor, in 290 making his third wife Berenice queen of Egypt.

Ptolemy I Soter now dominates Cyprus, Phoenicia and Palestine.

He abdicates the throne of Egypt and Libya in 285 (possibly on June 26) in favor of his son by Berenice, Ptolemy II Philadelphus, who had in 289 been made made coregent.

His eldest (legitimate) son, Ptolemy Keraunos, whose mother, Eurydice, the daughter of the Alexandrine regent Antipater, had been repudiated, flees to the court of Lysimachus, the king of Thrace, Macedon, and part of Asia Minor, who is married to Ptolemy’s half-sister, Arsinoe.