Marc Antony lost to Augustus in a battle for control of Rome and then went to Egypt to be with Cleopatra?
The Battle of Actium. The official story is that Marc Antony saw Cleopatra's ship leaving the battle, so he abandoned his ship and chased after her, eventually reuniting with her in Egypt. Without them, their fleet was easily polished off by the Roman fleet, and the last significant resistance to Rome was thereby finished. Rome would become an empire, and Augustus would have it all. There is modern speculation that Cleopatra and Marc Antony had previously intended to run rather than fight this battle.