Act 4, scene 1
During the truce, Aeneas welcomes the Greeks Deiphobus and Diomedes to Troy. Paris explains to Aeneas that they are to go to Calchas’s house and exchange the now freed Antenor for Cressida, as agreed. Paris in an aside says he knows Troilus will not be pleased about this arrangement.
Everyone exits except Paris and Diomedes. Paris asks Diomedes who deserves Helen more, himself or Menelaus. Diomedes responds scornfully, saying they both have equal claim to Helen but that she is absolutely dishonored by her situation and so is worth little. He calls her a whore. He is equally damning about Menelaus, calling him a cuckold, and he calls Paris a lecher. Diomedes also reminds Paris of the number of lives lost on both sides because of the war over Helen.
In no more than twenty lines Diomedes gives a stinging indictment of the war and its cause. He speaks in vituperative terms about Helen and is obviously disgusted that such a long, bitter, and costly war is being fought over such a worthless cause. He states explicitly what has been implied many times up to this point in the play.
Act 4, scene 2
Troilus and Cressida have spent the night together and it is now morning. Troilus says it is time for him to go, although Cressida protests. Pandarus enters, to Cressida’s annoyance. She chides him, and then another visitor, Aeneas, arrives, asking for Troilus. Pandarus pretends that Troilus is not there, but Troilus soon appears. Aeneas tells him that Cressida must be handed over to the Greeks. Troilus is dismayed but knows there is nothing he can do to alter the situation. He tells Aeneas not to tell anyone that he, Troilus, was found at Calchas’s house, with Cressida.
Pandarus is infuriated with the decision to exchange Cressida for Antenor.
He breaks the news to Cressida, who says she refuses to go.
Cressida again indulges in unintended irony when she says “Make Cressid’s name the very crown of falsehood / If she ever leave Troilus!” (lines 103-04). (This is actually known as dramatic irony, when the audience understands something different from the speaker’s words than what the speaker intends or realizes.)There is also a hint that Cressida is not quite the innocent young maiden that Troilus seems to think she is. She is in fact rather worldly wise. When Troilus says early in the morning that he has to leave, Cressida responds, “You men will never tarry,” (line 16) which seems to suggest more knowledge of the ways of men than might be thought proper for a young unmarried woman. This is just one of several hints in the play about Cressida’s character.