The Mexican Revolution, from 1910 to about 1920, was a period of great political upheaval during which the majority of the stanzas known today were written. Political symbolism was a common theme in these verses, and explicit and implicit references were made to events of the war, major political figures, and the effects of the war on the civilians in general. Today, few pre-Revolution verses are known, and the most commonly quoted portion of the song are the two Villist anti-Huerta stanzas: