To strengthen his control over the empire, Perdiccas agreed to marry Nicaea, the daughter of the satrap of Macedonia, Antipater. However, he broke off the engagement in 322 BC when Olympias, mother of Alexander the Great, offered him the hand of Alexander's full sister Cleopatra. Given the intellectual disability of Philip III and the limited acceptance of the boy, Alexander IV, due to his mother being a Persian, the marriage would have given Perdiccas a claim as Alexander's true successor, not merely as regent.