Antigone is the third installment in Sophocles' trilogy about the disastrous fate which torments the royal house of the Greek city-state of Thebes. The first two stories mainly concern Oedipus, who kills his father and marries his own mother (hence, the "Oedipus complex" in Freudian psychology). Eventually, Oedipus, who has four children, two sons and two daughters, is exiled from Thebes while his brother-in-law, Creon, rules as king. Oedipus's two sons soon clash over who will assume their father's throne. Creon sides with Eteocles and Polyneices is forced into exile where he raises an army and attempts to invade Thebes. At one of the gates of city, the brothers meet and wind up killing each other. As Antigone opens, it is the day after the battle and Eteocles has been buried with full military honors, but Polyneices has been deemed an enemy of the state and left unburied. This was a very harsh sentence to the Greeks because their religious laws required the performance of certain burial rites. If a body was left to decay in the open, then its soul would never be at rest. The play concerns itself with the clash between Antigone, one of Polyneices's sisters, and Creon over the burial of the brother.