In Troy, Pandarus converses with a servant while he waits to speak with Paris and Helen. When they come in, he compliments Helen profusely, and asks her to excuse Troilus if Priam asks about him at dinner that night. Paris and Helen ask where Troilus will be dining, and Pandarus refuses to tell him—but they both guess that he will be in pursuit of Cressida, and they make bawdy jokes about it as they depart to greet the returning warriors.
Pandarus finds Troilus pacing about impatiently in an orchard, and assures him that his desire for Cressida will soon be satisfied. He goes out, leaving Troilus giddy with expectation, and brings in Cressida; after urging them to embrace, Pandarus departs. Left alone, they profess their love for one another, and each pledges to be faithful to the other. Pandarus returns, and Cressida worries about what she is doing and considers leaving, but Troilus reassures her and again pledges to be faithful, declaring that thereafter history will say of all lovers that they were as "true as Troilus." Cressida declares that if she ever strays from him, she hopes that people will say of false lovers that they were as "false as Cressidas." Pandarus observes the compact, and then leads them off to a secluded bedchamber to consummate their passion.
Meanwhile, in the Greek encampment, Cressida's father, Calchas, who has betrayed Troy in order to join the Greeks, asks the Greek general to grant him a favor. He asks that they exchange the Trojan commander Antenor, whom they have recently captured, for his daughter, so that he might be reunited with her. Agamemnon agrees, and orders Diomedes to supervise the exchange. On Ulysses's advice, the Greek commanders then file past Achilles's tent, and scorn the proud warrior, ignoring his greetings and making him uneasy. He goes to Ulysses and asks him why he is being scorned, and Ulysses tells him that he is no longer a hero—that Ajax is the man of the hour, and that because Achilles's own heroic exploits are past, he will be forgotten quickly. That, says Ulysses, is the way the world works: good deeds are quickly forgotten, and only the present is remembered. He then informs Achilles that he knows a secret, namely, that Achilles is in love with a Trojan princess, and suggests that Achilles could restore his fame and honor if he stopped dallying with enemy women and took the field.
When Ulysses is gone, Patroclus tells Achilles to follow Ulysses's advice; seeing that his "reputation is at stake" (III.iii.227), and Achilles agrees. Thersites comes in and reports that Ajax is now striding about the camp, completely puffed up with his own importance. Patroclus persuades the foul-tongued slave to talk Ajax into bringing Hector, safely conducted by Agamemnon, to Achilles's tent after their fight the next day, so that Achilles may speak with Hector.
After a long hiatus amid the Greek camp and the political counsels of the Trojans, the action finally returns to the romance of the play's title. (It is, indeed, one of the weaknesses in the story that the romance and the political action are not integrated until late in the play.) These scenes mark the culmination of Troilus and Cressida's romance—one cannot exactly call it courtship, since it seems pointed toward consummation of their passion, not marriage. Their professions of love are poetic and contain a number of memorable phrases, including Troilus's comment that "this is the monstrosity in love, lady, that the will is infinite and the execution confined; that the desire is boundless and the act a slave to limit" (III.ii.75-77). This idea is appropriate to the play, in which the lovers are "confined" and "slaves to limit"—the limits imposed by the political situation in which they find themselves. Cressida's pledge to remain true to Troilus carries a poignant sense of foreshadowing, since the audience knows that she will not remain true—and that "false as Cressida" will actually become a common expression.
However, the scene is not nearly as poignant as it might be, since the eager Pandarus—who seems to derive an almost voyeuristic pleasure from his role as go-between—is constantly popping in, interjecting a sordid note into the proceedings. The contrast with, say, Romeo and Juliet, is striking: in that play, too, there is a go-between (Friar Laurence) who brings the lovers together, but their love is consummated after marriage, whereas Troilus and Cressida never even mention matrimony. For them, despite the pretty poetry, lust is the driving emotion, and so Pandarus's parting comment is entirely appropriate: "and Cupid grant all tongue-tied maidens here / Bed, chamber, Pandar to provide this gear" (III.ii.212-13).
In the Greek camp, Ulysses's cunning is on display in the way he manipulates Achilles. His lengthy discourse on time and reputation, which is his second great philosophical speech, convinces Achilles that his reputation is on the wane: "Time hath, my lord, a wallet at his back, / Wherein he puts alms for oblivion. / A great-sized monster of ingratitudes. / These scraps are good deeds past, which are devoured / As fast as they are made, forgot as soon / As done" (III.ii.145-150). Even more effective, though, is the blackmail that follows, as Ulysses reveals that he knows all about Achilles's affair with a Trojan princess. Here, his earlier speech about the importance of a strong state takes on a sinister cast:
There is a mystery—with whom relation Durst never meddle—in the soul of state, Which hath an operation more divine Than breath or pen can give expressure to. All the commerce you have had with Troy As perfectly is ours as yours, my lord.(III.iii.201-206)
It is Ulysses's role as spymaster—perhaps meant to resemble the sinister spymasters of Queen Elizabeth in Shakespeare's England—that has led some critics to suggest that he, and not the brutish Achilles, is the true villain of the piece.