By tragic accident.
In a common device of Greek tragedy, in an attempt to evade a fate given him by the Oracle at Delphi (that stated he would slay his father and marry his mother), he ended up doing it anyway without even knowing it. In this case, Oedipus never knew that his real father was Laius King of Thebes, but when Laius offended Oedipus by cutting him off at a crossroads, the latter retaliated by killing the former. Later on, he ends up outsmarting a sphinx. Then, he comes upon Thebes itself, where the people didn't realize that Oedipus had killed their king, but overjoyed that he had ended the sphinx's reign of terror and gave him the throne as reward.
The priest's speech reveals that Laius, the previous ruler of Thebes has been murdered. Oedipus has become ruler by succession, as he is Laius' son. The priest says that Thebes will not be released from the plague until the murderer has been found and either executed or banished.
Thebes is the setting of Oedipus Rex because it is the place where the story begins.
Yes, Oedipus is a tyrannical ruler in "Oedipus Rex" by Sophocles (495 B.C.E. - 405 B.C.E.).Specifically, a ruler is tyrannical if he seizes power illegally in ancient Greece. That description fits Theban King Oedipus. He ends up as King of Thebes because the job is open and because he marries Thebes' widowed queen. But King Laius dies because he is killed, and that killer turns out to be Oedipus. Oedipus therefore ascends the throne by illegal means.
Oedipus is king of Thebes
Thebes was the land that Oedipus ruled.
Jocasta is the Queen of Thebes and the mother of Oedipus.
Thebes Thebes
Thebes is the home of Oedipus throughout most of the book although he was born in Cadmus.
To bring an end to the failing harvests, declining birth rate and ailing livestock is what the high priest of Thebes asks Oedipus to do in the play "Oedipus Rex" by Sophocles (495 B.C.E. -- 405 B.C.E.).Specifically, the priest considers Oedipus a savvy ruler who successfully makes it up as he goes along. According to him, Oedipus is adept at figuring things out on his own or getting good advice from the gods and his peers. So there is no reason why Oedipus cannot get Thebes through its latest crisis ... or so the priest assumes.
Oedipus is King of Thebes.
Corinth in actuality but Thebes in Oedipus' mind is what Oedipus' adopted hometowns is in "Oedipus Rex" by Sophocles (495 B.C.E. - 405 B.C.E.).Specifically, Oedipus is born in Thebes. But he is fostered at a very, very early age into the royal house of Thebes. Years later, he leaves Corinth and settles down in Thebes. Even more years pass before Oedipus realizes that Thebes is his actual, not adopted, hometown.
Thebes.