It is now October 42 b.c., more than two and a half years since the assassination of Caesar, and Cassius says to his aide:

—Act V, scene i, lines 70-72

Since we don't know in what year Cassius was born, we can't say how old he was on the day of the Battle of Philippi. However, Plutarch refers to him as older than Brutus (a view Shakespeare adopts) and Brutus may have been born in 85 b.c. It would seem then that Cassius must be in his mid-forties at least and possibly pushing fifty.

Cassius does not find the fact that the battle will be fought on his birthday to be a good omen. He does not want to fight it. He says to Messala:

—Act V, scene i, lines 73-75

This is a reference to the fact that it is Brutus, not Cassius, who is pushing for battle. Cassius, who let himself be overruled, reminds himself, sadly, that Pompey was similarly forced into battle at Pharsalia, six years before, by the hotheads among his councilors, when cautious delay might have served his cause better.

To unavailing regret that he had allowed himself to be swayed by Brutus, Cassius finds trouble in supernatural omens. He says:

—Act V, scene i, lines 76-78

Epicurus of Samos was a Greek philosopher who was a contemporary of the Zeno who had founded Stoicism. Epicurus' philosophy (Epicureanism) adopted the beliefs of certain earlier Greek philosophers who viewed the universe as made up of tiny particles called atoms. All change consisted of the random breakup and rearrangement of groups of these atoms and there was little room in the Epicurean thought for any purposeful direction of man and the universe by gods. Omens and divine portents were considered empty superstition.

Now, however, Cassius begins to waver. It seems two eagles, having accompanied the army from Sardis to Philippi, have now flown away, as though good luck were departing. On the other hand, all sorts of carrion birds are now gathering, as though bad luck were arriving.

Cassius' pessimism forces him to question Brutus as to his intentions in case the battle is lost. Brutus answers in high Stoic fashion. His actions will follow:

—Act V, scene i, lines 100-2

Stoicism held it wrong to seek refuge in suicide. The good man must meet his fate, whatever it is, unmoved. Cassius asks, sardonically, if Brutus is ready, then, in case of defeat, to be led in triumph behind the conqueror's chariot through the Roman streets (and, undoubtedly, with the jeers of the Roman populace ringing in his ears).

At once, Brutus' Stoicism fails him. As long as his Stoic demeanor brings him praise, it is well. If it is going to bring him disgrace he abandons it But he does so with characteristic self-praise:

—Act V, scene i, lines 110-12

Since both plan to die in case of defeat, they may never meet again. Brutus says:

—Act V, scene i, line 116

Cassius answers in kind and both are now ready for the battle, which takes up the rest of the play.

On both sides there was double command. Cassius on the seaward side opposed Antony; Brutus on the inland side opposed Octavius. The fortunes differed on the two flanks. Brutus had the advantage over Octavius and advanced vigorously. He sends messages of victory to the other flank by Messala, saying:

—Act V, scene ii, lines 3-6

But even now, in the midst of victory, Brutus judges wrongly. Brutus should, at all cost, have kept his part of the army from advancing in such a way that they could not support the other part in case of need. Instead, his men are overvictorious and fall to looting, when they ought to have wheeled down upon Antony's men.

Antony's army manages instead to drive hard against Cassius' wing. That wing breaks and flies and can receive no help. Titinius, Cassius' aide, says bitterly:

—Act V, scene iii, lines 5-8

Cassius' depression now costs him the final price. He does not realize the exact magnitude of Brutus' victory and therefore does not understand that even allowing for his own defeat, the battle is no worse than drawn.

A band of Brutus' horsemen making their way toward him is mistaken by him for the enemy. When his aide, Titinius, reconnoitering, embraces them gladly, the nearsighted Cassius thinks he is taken prisoner and that his own capture is imminent.

Cassius therefore calls his servant, Pindarus, saying:

—Act V, scene ii, lines 37-40

In Parthia, at the Battle of Carrhae, eleven years before, Cassius had carried through the greatest military achievement of his life. He had carefully husbanded the downhearted remnants of a defeated army and had safely brought them back to Syria.

He had not despaired then, but he did now. He orders his slave to kill him with the same sword that had once pierced Caesar. It is done and Cassius dies.