The Mexican Revolution (Spanish: Revolución mexicana) was a major armed struggle that started in 1910, with an uprising led by Francisco I. Madero against longtime autocrat Porfirio Díaz, and lasted for the better part of a decade until around 1920. Over time the Revolution changed from a revolt against the established order to a multi-sided civil war. This armed conflict is often categorized as the most important sociopolitical event in Mexico and one of the greatest upheavals of the 20th century.
 
After prolonged struggles, its representatives produced the Mexican Constitution of 1917. The Revolution is generally considered to have lasted until 1920, although the country continued to have sporadic, but comparatively minor, outbreaks of warfare well into the 1920s. The Cristero War of 1926 to 1929 was the most significant relapse into bloodshed.
 
The Revolution led to the creation of the Partido Nacional Revolucionario ("National Revolutionary Party") in 1929; it was renamed the Partido Revolucionario Institucional (Institutional Revolutionary Party) (PRI) in 1946. Under a variety of leaders, the PRI held power until the general election of 2000.

After Benito Juárez's death in 1872, Porfirio Díaz took over as Mexico's leader. As allies the two men had fought against the French in the Battle of Puebla, but once Juárez rose to power Díaz tried to unseat him. Díaz began his tenure as president in 1876 and ruled until May 1911 when Francisco I. Madero succeeded him, taking office in November. Díaz's regime is remembered for the advances he brought in industry and modernization, at the expense of human rights and liberal reforms.
 
Díaz's rule from 1876 to 1911 has become known as the Porfiriato era. Díaz had a strict "No Re-election" policy whereby presidents could not serve consecutive terms in office. He followed this rule when he stepped down (1880) after his first term and was succeeded by Manuel González. Gonzalez was controlled by Diaz and was commonly known as Diaz's puppet. The new president's period in office was marred by political corruption and official incompetence. When Díaz ran in the next election (1884), he was a welcome replacement. In future elections Díaz conveniently put aside his "No Re-election" slogan and ran for president in every election.
 
Diaz was an early liberal, but changed his views after Juarez took office. He became the dictator against whom he had warned the people. Through the army, the Rurales—a paramilitary force that kept order in the countryside—and gangs of thugs, Diaz frightened people into voting for him. When bullying citizens into voting for him failed, he simply rigged the votes in his favor. He justified his stay in office by claiming that Mexico was not yet ready to govern itself; only he knew what was best for his country and he enforced his belief with a strong hand. "Order followed by Progress" were the watchwords of his rule.

In 1910 Francisco I. Madero, a young man from a wealthy family in the northern state of Coahuila, stated that he would be running against Díaz for the presidency in the next election. To ensure Madero did not win, Díaz had him thrown in jail, then declared himself the winner. Madero soon escaped and fled for a short period of time to San Antonio, Texas, United States. On October 5, 1910, Madero issued a "letter from jail" called the Plan de San Luis Potosí, with its main slogan Sufragio Efectivo, No re-elección ("free suffrage and no re-election"). It declared the Díaz regime illegal and called for revolt against Díaz, starting on November 20. Though Madero's letter was not a plan for major socioeconomic revolution, it offered the hope of change for many disadvantaged Mexicans.
 
Madero's vague promises of agrarian reforms attracted many peasants throughout Mexico. He received the support from them that he needed to remove Díaz from power and raised an army consisting mostly of ordinary farmers, miners, and other working-class Mexicans, along with much of the country's Indian population. Madero's army fought Diaz's forces with some success, and he attracted the forces of other rebel leaders like Pancho Villa, Emiliano Zapata and Venustiano Carranza, and they eventually joined together to fight Diaz. Diaz's army suffered several major defeats, and his administration started to fall apart..
 
In late 1910 revolutionary movements broke out in response to Madero's letter. Pascual Orozco, along with governor Abraham González, formed a powerful military union in the north and took Mexicali and Chihuahua City, although they were not especially committed to Madero. These victories encouraged alliances with other revolutionary leaders, including Pancho Villa. Against Madero's wishes, Orozco and Villa fought for and won Ciudad Juárez, bordering El Paso, Texas, along the Rio Grande.

In early 1913, Gen. Victoriano Huerta, who commanded the armed forces, conspired with U.S. Ambassador Henry Lane Wilson and Mexican politicians Félix Díaz and Bernardo Reyes to remove Madero from power. La decena trágica was an event in which ten days of sporadic fighting in a faked battle occurred between federal troops led by Huerta and Díaz's conservative rebel forces. This fighting stopped when Huerta, Félix Díaz and Henry Lane Wilson met and signed the "Embassy Pact" in which they agreed to move against Madero and install Huerta as president. After this was accomplished, however, Zapata reunited with Villa and the other revolutionaries. Orozco, however, sided with Huerta and Huerta made him one of his generals.
 
When Huerta gained power and became president, most world governments acknowledged him as the rightful leader. However, incoming U.S. President Woodrow Wilson not only refused to recognize Huerta's government, but replaced Henry Lane Wilson as U.S. Ambassador with John Lind, a Swedish-American. Wilson and his Secretary of State William Jennings Bryan—and many Mexicans—saw Huerta as a usurper of presidential power in violation of the Constitution of Mexico.
 
Venustiano Carranza, a politician and rancher from Coahuila, was at the forefront of opposition to Huerta, and organized his own rebel army, called the Constitutionalists, with the secret support of the United States. On March 26, 1913, Carranza issued the Plan de Guadalupe, which refused to recognize Huerta as president and called for war between the two factions. Leaders such as Villa, Zapata, Carranza and Álvaro Obregón led the fight against Huerta. In April 1914, U.S. opposition to Huerta had reached its peak when American forces seized and occupied the port of Veracruz, cutting off arms, supplies and money from Germany, which supported Huerta. In late July the situation worsened for Huerta, and after his army suffered several defeats, he stepped down and fled to Puerto México.

José Doroteo Arango Arámbula, better known as Francisco "Pancho" Villa, came from the northern state of Durango. With his army, known as "Villistas", he joined the ranks of the Madero movement. He led his Villistas in many battles, including the attack on Ciudad Juárez in 1911, which led to the defeat of Mexican President Gen. Porfirio Díaz.
 
In March 1912, in Chihuahua, Gen. Pascual Orozco revolted. In April, President Francisco Madero commanded Gen. Victoriano Huerta of the Federal Army, to put down the revolt. The governor of Chihuahua mobilized the state militia to supplement General Huerta. Pancho Villa was a colonel in the Chihuahua state militia, and he was called up at this time. In mid-April, Villa, at the head of 400 irregular troops, joined the forces commanded by General Huerta. In May, one of Villa's subordinates appropriated an expensive horse. When the owner complained to Huerta, Huerta ordered Villa’s subordinate to be executed. Villa objected, and Huerta relented, but Huerta nursed a grudge. In June, Villa notified Huerta that inasmuch as the Orozco revolt has been put down, he and his irregulars would consider themselves no longer under Huerta's command, and would depart. Huerta became furious, and ordered that Villa be executed. Raúl Madero, Madero's brother, intervened to save Villa's life. Jailed in Mexico City, Villa fled to the United States. Soon after the assassination of President Madero he returned to Mexico to fight Huerta, although he had only a handful of companions with him. However, by 1913 his forces had swelled into an army of thousands, called the División del Norte (Northern Division). Villa and his army, along with Carranza and Obregón, joined forces to fight against the Huerta dictatorship.
 
Villa and Carranza had different goals. Because Villa wanted to continue the revolution, he became an enemy of Carranza. After Carranza took control in 1914, Villa and other revolutionaries who opposed him met at what was called the Convention of Aguascalientes. The convention deposed Carranza in favor of Eulalio Gutiérrez. In the winter of 1914 Villa's and Zapata's troops entered and occupied Mexico City. Villa's treatment of Gutiérrez, and the citizenry in general, outraged more moderate elements of the population, and Villa was forced from the city in early 1915.

Venustiano Carranza became president in 1914, after the overthrow of the Huerta government. He was driven out of Mexico City by Villa and Zapata in December 1914, but later gained the support of the masses by the development of a program of social and agrarian reform. He was elected president in 1917. To try to restrain the revolutionary slaughter, Carranza formed the Constitutional Army to try to bring peace by the adoption—albeit reluctantly—of the majority of the rebels' social demands into the new constitution. The socialist constitution addressed foreign ownership of resources (Article 27), an organized labor code (Article 123), the role of the Roman Catholic Church in education (Article 3), and land reform.

Emiliano Zapata was a leading figure in the Mexican Revolution. He is considered one of the national heroes of Mexico: towns, streets and housing developments named "Emiliano Zapata" are common across the country. His image has been used on Mexican banknotes. People have long taken different sides on their evaluation of Zapata and his followers: some considered them bandits, but to others they were true revolutionaries who worked for the peasants. Presidents Porfirio Díaz and Venustiano Carranza called Zapata a womanizer, barbarian, terrorist and bandit. Conservative media nicknamed Zapata "The Attila of the South".
 
Many peasants and indigenous Mexicans admired Zapata as a practical revolutionary whose populist battle cry, "Tierra y Libertad" (Land and Liberty), was spelled out in the Plan de Ayala for land reform. He fought for political and economic emancipation of the peasants in southern Mexico. Zapata's trademark saying was, "It's better to die on your feet than to live on your knees." Zapata was killed in 1919 by Gen. Pablo González and his aide, Col. Jesús Guajardo, in an elaborate ambush. Guajardo set up the meeting under the pretext of wanting to defect to Zapata's side. At the meeting, Gonzalez's men assassinated Zapata.