Now, Cinesias and the Men's Chorus complain about how sexually frustrated they are.
Just then, a Herald shows up from Sparta. Even though he denies it at first, eventually Cinesias makes the Herald admit that he is sporting a massive erection.
The Herald explains that all the men of Sparta are in the same state—and so are their allies. The trouble all got stirred up by Lampito, he says, who organized the women in a sex strike.
Cinesias now realizes that all the women of the world are taking part in one big conspiracy. Figuring that the only solution now is to make peace, he sends the Herald back to Sparta to fetch delegates. Cinesias says that, in the meantime, he'll get the Athenians ready to receive them. He leaves the stage.
Once those guys have left, the Women's Leader tries to make friends with the Men's Leader. She helps him put his shirt back on, and helps remove a gnat from his eye. Then she kisses him, even though he protests.
After this, the Men's Chorus and Women's Chorus join together into a single Chorus. Together, they sing a short song about how they are happy now, and how they want to be friends with everyone—only they don't really want to have to share all their stuff.
Just then, who should show up but… the delegates from Sparta. What's more, they're all sporting massive boners. They say that they can't stand it anymore: they're ready for peace.
Next, the Athenians show up. They, too, are sporting seriously swollen members.
Once the Athenians learn that the Spartans are there to negotiate a peace treaty, they suggest bringing Lysistrata along to help smooth out the deal. The Spartans are cool with that.