A period of political and social turmoil in Mexico. The roots of the revolution can be traced to the demographic, economic, and social changes that occurred during the rule of President Porfirio Díaz, known as the Porfiriato (1876–1911). The regime became increasingly centralized and authoritarian, favouring Mexico’s traditional and newly emerging élites, but failing to incorporate growing urban middle-class and labour groups into national politics. In 1910 Francisco Madero, the leader of the Anti-Re-electionist movement, received an enthusiastic response to his call to arms to overthrow the dictator. Although Díaz resigned in May 1911 and Madero was elected President, he failed to satisfy either his radical supporters or his Porfirian enemies, and was assassinated in a counter-revolutionary coup led by General Victoriano Huerta in 1913. Huerta was defeated by an arms embargo, diplomatic hostility from the USA, and a coalition of revolutionary factions led by Emiliano Zapata, Pancho Villa, Venustiano Carranza, and Alvaro Obregon. The victorious revolutionaries split into Constitutionalists (Carranza and Obregon), who sought to reform the 1857 Liberal Constitution, and Conventionists (Zapata and Villa) who wished to implement the radical proposals of the convention of Aguascalientes (1914). The civil war which ensued was protracted and bitter. In February 1917 the reformed Constitution was promulgated. However, the document was largely ignored, and Carranza’s procrastination prompted his overthrow and assassination in 1920. Mexico’s new revolutionary leaders faced the difficult tasks of economic regeneration and the reconstitution of central political authority, but were hampered by strong opposition from the Catholic Church. Tension culminated in the so-called War of the Cristeros (1928–30), in which thousands of Christian peasants arose in protest against the new “godless” state, and were finally defeated at the battle of Reforma (1930). When President Avila Camacho (1940–46) was elected, a period of consolidation and reconciliation began, marking the end of the revolution.