The Cristero War (), also known as the Cristero Rebellion or , was a widespread struggle in central and western Mexico from 1 August 1926 to 21 June 1929 in response to the implementation of secularist and anticlerical articles of the 1917 Constitution. The rebellion was instigated as a response to an executive decree by Mexican President Plutarco Elías Calles to strictly enforce Article 130 of the Constitution, a decision known as Calles Law. Calles sought to eliminate the power of the Catholic Church in Mexico, its affiliated organizations and to suppress popular religiosity. The rural uprising in north-central Mexico was tacitly supported by the Church hierarchy, and was aided by urban Catholic supporters. The Mexican Army received support from the United States. American Ambassador Dwight Morrow brokered negotiations between the Calles government and the Church. The government made some concessions, the Church withdrew its support for the Cristero fighters, and the conflict ended in 1929. The rebellion has been variously interpreted as a major event in the struggle between church and state that dates back to the 19th century with the War of Reform, as the last major peasant uprising in Mexico after the end of the military phase of the Mexican Revolution in 1920, and as a counter-revolutionary uprising by prosperous peasants and urban elites against the revolution's rural and agrarian reforms. Background Conflict between church and state The Mexican Revolution was the costliest conflict in Mexican history. The overthrow of the dictator Porfirio Díaz caused political instability, with many contending factions and regions. The Catholic Church and the Díaz government had come to an informal modus vivendi in which the state formally maintained the anticlerical articles of the liberal Constitution of 1857 but it failed to enforce them. A change of leadership or a wholesale overturning of the previous order were potential sources of danger to the Church's position. In the democratizing wave of political activity, the National Catholic Party (Partido Católico Nacional) was formed. After president Francisco I. Madero was overthrown and assassinated in a February 1913 military coup which was led by General Victoriano Huerta, supporters of the Porfirian regime were returned to their posts. After the ouster of Huerta in 1914, members of the National Catholic Party and high-ranking Church figures were accused of collaborating with the Huerta regime, and the Catholic Church was subjected to revolutionary hostilities and fierce anticlericalism by many northern