The function of the letter from Luis Cervantes to Venancio in Part 3, Chapter 1, of The Underdogs serves the function of pointing out the alternatives to fighting and the futility of unreasoned choices. Cervantes suggests the irrationality that underpins the peasants unreasoning devotion to the revolution when he expresses in his letter that he is not surprised that Pancracio and Manteca killed each other something so banal, so trivial, as gambling. In juxtaposition to this he draws a picture of hope and luxurious nurturing life by suggesting they open a restaurant in the United States.
Additionally, it causes the revolutionaries to begin to question and reason since they know that the Federation they began the fight to oppose has been defeated. In juxtaposition to this stands the suggestion of the decaying futility of unreasoned actions once set in motion. This idea is highlighted by the comparison in The Underdogs between Demetrio--who has a peasants unreasoned for the revolution--and Navera--who has a knowledgeable commitment to the facts and ideology of the revolution.