Julius Caesar tells the story of how the Roman Republic came to its end. The Republic was viewed as a high point in history, both by its participants and by those who came after, because its institutions divided power among a number of people (senators and tribunes) rather than concentrating it in one person. Political decisions were made through public debate and persuasive argument, and in theory the ideas that would be best for Rome would prevail rather than the will of one ruler. At the beginning of the play the Republican mode of government is under serious threat, since Julius Caesar is ruling as a dictator and may soon be crowned as a king. In fact, the Republic doesn’t dissolve with Caesar’s coronation, but rather with his murder. In assassinating Caesar, Brutus thinks that he is striking a blow for Republican ideals and doing what is best for Rome, but in actuality he has let himself be manipulated by Cassius and the other conspirators. The assassination actually represents their personal grievances, fears, and self-interest more than the interest of Rome. Rather than restoring Republican balance, Caesar’s murder unleashes a brutal civil war in which the self-interest and power of the warring parties are all that matter.
The first scene of the play depicts the conflict between Rome’s Republican past and Caesar’s ascendance. The commoners march in celebration of Caesar’s victory over Pompey but the Tribunes scold them and chase them off, arguing that Pompey was a celebrated Roman too so Caesar’s triumph is not truly a triumph for Rome. As Caesar is loudly cheered by crowds offstage, we see Brutus admitting to Cassius that he is worried about what’s happening to the Republic. But while Brutus is not wrong to see Caesar as a threat to Republican institutions—Caesar really does see himself as set apart from other men and intends to rule by his own will, unswayed by other people’s arguments—we see clear signs throughout the first two acts that the idea of assassinating Caesar is a dark and mistaken path for Brutus to take. Cassius is the person tempting Brutus in this direction, and we see more clearly than Brutus does that Cassius’s motives are personal rather than idealistic. Caesar describes Cassius as having a “lean and hungry” look, as if he lies awake at night brooding. Cassius’s story to Brutus about rescuing Caesar from the river but then later finding himself Caesar’s inferior suggests his resentment about being undervalued personally rather than Rome’s institutions being threatened. Most significantly, we see Cassius deliberately mislead Brutus by arranging to have fake notes left on his chair and thrown in at his window as if the people were encouraging him to rise against Caesar. Brutus explicitly comments to the audience after Brutus leaves the stage at the end of Act I, Scene ii that he’s just manipulated him.
The first two acts of the play thus show the rise of the conspiracy and Brutus’s decision to join it. The conspirators present themselves as motivated by a desire to save the Roman Republic and overthrow tyranny, but the play teaches us not to take their claims at face value. The other conspirators openly admit to each other that they need Brutus to participate because they know that their actions would be seen as treasonous without his reputation to make them look better than they are. We see Cassius’s manipulation of Brutus in Act I, then Brutus’s debate with himself at the beginning of Act II, in which the tortured logic of his reasons shows how out of touch with the truth he is. We see Brutus reject his wife Portia, who represents the nobler side of his character. We see the sinister masked figures of the conspirators appearing at Brutus’s door, and finally, in Act III, Brutus and the others betray and stab Caesar to death.
After the assassination, the conspirators’ survival depends on their ability to convince the populace and the other senators of Rome that what they did was for the sake of the Republic. As Cassius points out, in order to control how their actions are understood, they must either kill or at least silence Mark Antony, Caesar’s loyal and powerful friend who is likely to speak against them. But Brutus makes the fatal error of allowing Antony to speak, because he is still deluded about himself and his own actions, clinging to the idea that he is the most honorable of Romans and that no one would dare dispute his honor. The climax of the play comes when Antony, by juxtaposing Caesar’s accomplishments, his generous will, and his corpse’s brutal wounds with the repeated statement that “Brutus is an honorable man,” persuades the people of Rome that Brutus and his co-conspirators aren’t honorable at all. Brutus and Cassius are forced to flee Rome and the country is plunged into civil war.
When Brutus and Cassius meet in Act IV, at the head of their armies, and begin arguing with each other, we can see that they’re doomed. Both of them have weakened their own cause by continuing to display the same flaws each exhibited in the early acts. Cassius has acted out of self-interest and now has angered Brutus by selling important offices for personal gain and refusing to send Brutus funds to raise an army. Brutus continues to be crippled by the delusion that he is more honorable than other people; he thus attacks his chief ally for his dishonorable actions and has himself failed to raise funds for his army because he refuses to get money “by vile means.” Though the two reconcile, Brutus refuses to listen to Cassius (who at least usually has good instincts for self-preservation) and leads their forces into an ill-fated assault. Because they don’t actually represent a political movement for republicanism and because the assassination was a tragic crime, Cassius and Brutus end by killing themselves, power in Rome passes into the hands of Mark Antony and Octavius, and the tyranny that Brutus hoped to avert comes to pass.