In the novel The Underdogs by Mariano Azuela, in what ways is the theme of "futility" demonstrated?

Mariano Azuela's novel Los de Abajo, or The Underdogs reads, almost in its entirety, as an essay on futility in a variety of ways. 

Let's start with Demetrio's entry in the Revolution. Rather than joining to defend his principles, he actually does it just to get back at los federales. Being that the revolution is bloody and futile on its own, joining it for shallow reasons makes everything all the more senseless. 

Then come the products of the revolution itself. What starts as a united front ends up in disaster. The relationship between Camila and La Pintada, for example, becomes marred by jealousy and ends with the killing of Camila by La Pintada.

Another example of futility is that, as much as the revolutionaries shouted and attempted to battle against the federales and oppression, their inner factions and ongoing fighting and dissatisfaction contributed to the disbanding of many revolutionary groups, making the struggle even more futile: They were fighting within a fight, against one another and against the system that wanted to put them down at the same time. What is purposeful, useful, or even sensible about that?

More futility: Pancho Villa and Venustiano, once united by the vision of revolutionary victory, become rivals. El Manteca and Pancracio, also meant to be comrades, literally kill one another over a game of cards. El güero Margarito commits suicide.

Meanwhile, the revolution keeps roaring along, taking lives with it and changing absolutely nothing. The oppression continues, as well as the injustice.

The ending of the novel is perhaps more ironic than anything else. Demetrio and the few left in his troop make one last attempt at fighting the Carranza troops as one last futile act of rebellion...only to get killed, each and every one of them, by the enemy.