How do the achievements of the historical figure of octavius add meaning to the plays ending

The final act of Julius Caesar features a battle between the military forces of Brutus and Cassius and those of Antony and Octavius. When Antony and Octavius gain the upper hand, Cassius chooses to kill himself rather than be captured, and Brutus soon follows suit. After Brutus’s death, Antony and Octavius give short speeches in praise of Brutus. Antony characterizes Brutus as “the noblest Roman of them all,” indicating that he was the only conspirator who acted for the good of Rome. Octavius echoes Antony, concluding that Brutus was indeed an honorable man. Despite their celebration of Brutus’s honor, the two men still implicitly condemn the murder to which Brutus’s commitment to Rome led him. The play’s ending is therefore ambivalent, meaning that it registers mixed feelings about what has come to pass. For anyone who knows Roman history, the ending also proves ironic. Following the events depicted in the play, Octavius goes on to behave dishonorably toward Antony, which leads to a civil war that results in Antony dying and Octavius becoming the first emperor of the Roman Empire. For men who hold honor so highly, it’s ironic that their own honor would fail and bring out the very thing the conspirators had attempted to prevent: the crowning of an emperor.

Explanation:  https://www.sparknotes.com/shakespeare/juliuscaesar/what-does-the-ending-mean/

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