The Battle of Ipsus was fought between some of the Diadochi (the successors of Alexander the Great) in 301 BCE near the town of Ipsus in Phrygia. Antigonus I Monophthalmus, ruler of Phrygia, and his son Demetrius I of Macedon were pitted against the coalition of three other successors of Alexander: Cassander, ruler of Macedon; Lysimachus, ruler of Thrace; and Seleucus I Nicator, ruler of Babylonia and Persia. The battle was a decisive defeat for Antigonus, who died during the battle.

The last chance to reunite the Alexandrine Empire had already been passed when Antigonus lost the Babylonian War and two thirds of his empire. Ipsus confirmed this failure. As Paul K. Davis writes, "Ipsus was the high point of the struggle among Alexander the Great’s successors to create an international Hellenistic empire, which Antigonus failed to do." Instead, the empire was carved up between the victors, with Ptolemy retaining Egypt, Seleucus expanding his power to eastern Asia Minor, and Lysimachus receiving the remainder of Asia Minor.