After decades of revolutionary upheaval and political violence that began early in the 20th century, Mexico had seemingly achieved stability and a relative level of social peace by the 1940s. The peasant revolution of 1910—beginning with its armed, insurrectionary phase (1910–1920) to the subsequent decades (1920–1940) that involved making “The Revolution” manifest in the everyday lives of Mexicans who (to borrow historian Jeffrey Pilcher’s metaphor) chose à la carte from the revolutionary menu—produced a durable political order characterized by an active level of popular participation and legitimacy. The peace was durable, yet potentially fragile since postrevolutionary rulers, contained within the confines of the Partido Revolucionario Institucional (PRI) and its previous incarnations, could not take the peasant masses for granted. Revolution had taught these masses something about their power, both its limitations and potential, to shape the content and form of the Mexican state.
After 1940, as the PRI gradually exhibited its preference for political authoritarianism and an economic project that rapidly industrialized and urbanized the country while pauperizing the countryside, a series of disparate popular protest movements continually emerged. Usually peaceful and basing their alternative modernizing visions on the 1917 Constitution and the radical policies of President Lázaro Cárdenas during the 1930s, these movements—peasant, organized labor, and student movements—often faced repression and violence at the hands of state agents and/or local-regional caciques when demanding political democracy and economic justice. The spectacular massacre of protestors in public spaces and the selective assassination of dissident movement leaders represent two of the tactics employed by the PRI to quell popular resistance in the post–1940 era. Yet, such instances of state violence also stimulated political and tactical radicalization as some protestors organized revolutionary expressions of armed struggle and guerrilla warfare. From 1940 to 1982, more than three dozen armed organizations emerged in almost every region, in both urban and rural settings, displaying a wide variety of revolutionary ideologies and practices. Beginning with Rubén Jaramillo’s 1943 armed resistance in Morelos and ending with the formal dissolution of the urban Liga Comunista 23 de Septiembre in 1982, these armed struggles generally shared the goal of overthrowing the PRI regime, seizing state power, and articulating a socialist vision for a post-PRI Mexico.