What is the main conflict in The Tower by Hugo von Hofmannsthal?

The Tower concerns the fate of Sigismund, a young prince whose father, King Basilius, has kept him locked in the tower because of a prophecy that claimed he would rise up against his father in rebellion. As the play opens, Sigismund, now twenty-one years of age, has been locked in a cage like an animal, unaware of his royal heritage. A physician who has examined Sigismund convinces Julian, the tower governor, to persuade the king to restore his son as heir to the throne. But, as soon as the king grants Sigismund this power, the son rises up and attacks his father. After the king's attendants overpower him, Sigismund is sentenced to death. On the day of his execution, however, a planned rebellion among the noblemen dethrones the king and Sigismund ascends the throne as the new king. A peasant rebellion, however, lead by Oliver, results in the assassination of Sigismund.