[1] In 338 BC,[2] Attalus's adopted niece Cleopatra Eurydice married king Philip II of Macedonia.
It is said that at the wedding, Attalus made a prayer that Cleopatra may give birth to a legitimate male heir to Philip.
[3][4][5][6] In the spring of 336 BC, Philip II appointed Attalus and Parmenion as commanders of the advance force that would invade the Persian Empire in Asia Minor.
After Philip II had been assassinated and Alexander became king (October 336 BC), his adopted niece Cleopatra Eurydice and her two children were all killed (Cleopatra Eurydice may have died by her own hand after the murders of her children).
[11] Even without the resentment between the two men that had occurred after the marriage of Cleopatra Eurydice, Alexander probably felt Attalus was too ambitious and popular with the Asian forces to remain alive, and would have good reason for revenge after the deaths of Cleopatra Eurydice and her children.