In Chapter 8 of In the Time of Butterflies, Minerva, Manolo, Nelson, and Leandro arrive at Patria's mother's new house in Conuco where Patria is staying. They awaken her in the night to announce that Ernesto "Che" Guevara and Fidel and Raul Castro in a coup d'etat have ousted Batista in Cuba. Happy to learn this news, Patria celebrates with her husband; later, she learns that after eighteen years of marriage, she is again pregnant.
With Minerva and Mate away fighting in the revolution, Patria unwittingly becomes involved as she cares for the children of Minerva and Mate. Even though Patria's husband Pedrito does not want her involved in the revolution, Patria is so moved by the killing of boys and men that she cannot help becoming involved; moreover, she soon enlists Pedrito in the causes of the revolution.
And, it is at this point in the novel that the title is also explicated,
I couldn’t believe this was the same Padre de Jesus talking who several months back hadn’t known his faith from his fear! But then again, here in that little room was the same Patria Mercedes, who wouldn’t have hurt a butterfly, shouting, “Amen to the revolution.”