Octavius and Antony enter the battlefield at Philippi with their armies. A messenger arrives to report that the enemy is ready for battle. Antony, the more experienced soldier, tells Octavius to attack from the left. Octavius refuses and replies that he will attack from the right and Antony can come from the left. Antony asks Octavius why he questions his authority, but Octavius stands firm.

The enemy factions—consisting of Brutus, Cassius, and their armies—enter; Titinius, Lucillius, and Messala are among them. Octavius asks Antony if their side should attack first, and Antony, now calling Octavius “Caesar,” responds that they will wait for the enemy to attack. Antony and Octavius go to meet Brutus and Cassius. The leaders exchange insults. Octavius draws his sword and calls for Caesar’s death to be avenged; he swears that he will not lay the sword down again until another Caesar (namely himself) adds the deaths of the traitors to the general slaughter. The leaders insult each other further before parting to ready their armies for battle.

After the departure of Antony and Octavius, Brutus calls Lucillius to talk privately. Cassius calls Messala to do the same. Cassius tells the soldier that it is his birthday and informs him of recent bad omens: two mighty eagles alighted on the foremost banners of their army and perched there, feeding from the soldiers’ hands; this morning, however, they are gone. Now ravens, crows, and other scavenger birds circle over the troops as if the men were diseased and weak prey. Cassius walks back to join Brutus and comments that the future looks uncertain; if they lose, they may never see each other again. Cassius asks Brutus if Brutus would allow himself to be led through Rome as a captive should they lose. Brutus replies that he would rather die than go to Rome as a defeated prisoner; he declares that this day “must end that work the ides of March begun”—that is, the battle represents the final stage in the struggle for power that began with the murder of Caesar (V.i.114). He bids Cassius “for ever and for ever farewell” (V.i.117). Cassius echoes these sentiments, and the men depart.

The battle begins between the scenes, and the next scene, comprising a scant total of six lines, depicts the two sides’ first surge against each other. Brutus sends Messala to Cassius to report that he senses a weakness in Octavius’s army and will push forward to exploit it.

The next scene finds Cassius standing on a hill with Titinius, watching the battle and lamenting its course. Though Brutus was correct in noting Octavius’s weakness, he proved overeager in his attack, and the tide of battle has turned against him. Pindarus now runs up to Cassius with a report: Antony’s troops have entered Cassius’s camp. He advises Cassius to flee to some more distant spot. Cassius refuses to move but, catching sight of a group of burning tents, asks if those tents are his. Titinius confirms that they are. Cassius then notices a series of advancing troops in the distance; he gives Titinius his horse and instructs him to find out whose troops they are. Titinius obeys and rides off.

Cassius asks Pindarus to ascend a nearby hill and monitor Titinius’s progress. Pindarus calls down his reports: Titinius, riding hard, is soon surrounded by the unknown men; he dismounts the horse and the unknown men cheer. Distraught at this news of what he takes to be his best friend’s capture, Cassius tells Pindarus to watch no more. Pindarus descends the hilltop, whereupon Cassius gives Pindarus his sword, covers his own eyes, and asks Pindarus to kill him. Pindarus complies. Dying, Cassius’s last words are that Caesar has now been revenged by the very sword that killed him.

Unexpectedly, Titinius now enters with Messala, observing that the battle rages on without sign of ending. Although Antony’s forces defeated those of Cassius, Brutus’s legions rallied to defeat those of Octavius. The men then discover Cassius’s body. Titinius realizes what has happened: when he rode out to the unknown troops, he discovered the troops to be Brutus’s; the men’s embrace of Titinius must have appeared to Pindarus a capture, and Cassius must have misperceived their joyful cheers of reunion as the bloodthirsty roars of the enemy’s men. Messala departs to bring the tragic news to Brutus. Titinius mourns over Cassius’s body, anguished that a man whom he greatly admired died over such a mistake. Miserable, Titinius stabs himself and dies.

Brutus now enters with Messala and his men. Finding the bodies, Brutus cries, “O Julius Caesar, thou art mighty yet”: even in death, Caesar is reaping revenge; he seems to turn events against his murderers from beyond the grave (V.iii.93). Brutus orders that Cassius’s body be taken away, and the men set off to struggle again with the armies of Antony and Octavius.

When Octavius refuses to agree to Antony’s strategic instructions before the battle, his obstinate resolution to follow his own will and his clarity of command echo Caesar’s first appearance in the play. In Act I, scene ii, Antony comments, “When Caesar says ‘Do this,’ it is performed”; such authority is the mark of a powerful leader (I.ii.12). Octavius, Caesar’s chosen successor, now has this authority too—his word equals action. Antony, noticing this similarity between adopted son and father, begins calling Octavius “Caesar.” Just as Caesar transforms his name from that of a mere mortal into that of a divine figure, Antony converts “Caesar,” once one man’s name, into the generic title for the ruler of Rome. In at least one way, then, Caesar’s permanence is established.

The exchange between the four leaders profits from close reading, as it compares the respective powers of words and swords to harm. When Brutus insists that “good words are better than bad strokes,” Antony replies, “In your bad strokes, Brutus, you give good words. / Witness the hole you made in Caesar’s heart, / Crying ‘Long live, hail Caesar’” (V.i.29–32). Antony suggests that Brutus’s use of rhetoric has been just as damaging to Rome as his physical blows, for by falsely swearing allegiance to Caesar he deceived and betrayed him—hypocritically, he murdered Caesar even as he cheered in support of him. Cassius returns the insult by comparing Antony’s words to an annoying bee’s buzzing, and Antony condemns Cassius and Brutus as “flatterers” (V.i.45). The politicians engage in a skillful rhetorical skirmish, but, ultimately, their words have no effective power. Since Brutus’s actions have proved his words treacherous and untrustworthy, the murder of Caesar can now be answered only in blood.

The tragic circumstances of Cassius’s death represent another instance of misinterpretation. They refer strongly to Caesar’s death: like Caesar, Cassius dies after failing to perceive the truth; and he dies from his own sword, the same sword that killed Caesar. Indeed, the entire scene attests to Caesar’s continuing power of influence from beyond the grave: as Cassius dies, he credits the murdered leader with his defeat. Brutus, with the ghostly visitor of the previous night fresh in his mind, also interprets Cassius’s death as the doings of a vengeful Caesar. In believing himself immortal, Caesar opened himself up to his murder by the conspirators, and his death seemed to disprove his faith in his own permanence. Yet now the power of Caesar appears to linger on, as events unfold in exact compliance with what Caesar would have wished.

Just as the misinformation that causes Cassius to commit suicide cheapens his death, so too do the manner and consequence of his death render it less noble. Cassius desires a virtuous death, and he believes that dying out of respect and sympathy for his captured friend will afford him just such an end: “O coward that I am, to live so long / To see my best friend ta’en before my face!” (V.iii.34–35). He cannot, however, bring himself to perform the necessary act; though he implies that his choice to die is brave, he does not possess the requisite bravery. Cassius’s last line widens this gap between his conception and reality: “Caesar, thou art revenged, / Even with the sword that killed thee” (V.iii.44–45). Cassius attempts to situate his death as a righteous, even graceful, working of dignified fate, and perhaps even to compare himself to the great Caesar. Yet while the sword that kills both is, fatefully, the same, the hands that drive it are not, ruining Cassius’s parallel. Immediately after Cassius’s death, no dedicated friend delivers a praise-filled, tearful eulogy celebrating his life. Rather, the only witness, Pindarus, a lowly slave, flees to his freedom, “where never Roman shall take note of him” (V.iii.49). Pindarus’s idea of escaping notice reflects upon Cassius and his ignoble deeds, for which history will not remember him kindly.