The military history of Mexico encompasses armed conflicts within that nation's territory, dating from before the arrival of Europeans in 1519 to the present era. Mexican military history is replete with small-scale revolts, foreign invasions, civil wars, indigenous uprisings, and coups d'état by disgruntled military leaders. Mexico's colonial-era military was not established until the eighteenth century. After the Spanish conquest of the Aztec Empire in the early sixteenth century, the Spanish crown did not establish on a standing military, but the crown responded to the external threat of a British invasion by creating a standing military for the first time following the Seven Years' War (1756–63). The regular army units and militias had a short history when in the early 19th century, the unstable situation in Spain with the Napoleonic invasion gave rise to an insurgency for independence, propelled by militarily untrained men fighting for the independence of Mexico. The Mexican War of Independence (1810–21) saw royalist and insurgent armies battling to a stalemate in 1820. That stalemate ended with the royalist military officer turned insurgent, Agustín de Iturbide persuading the guerrilla leader of the insurgency, Vicente Guerrero, to join in a unified movement for independence, forming the Army of the Three Guarantees. The royalist military had to decide whether to support newly independent Mexico. With the collapse of the Spanish state and the establishment of first a monarchy under Iturbide and then a republic, the state was a weak institution. The Roman Catholic Church and the military weathered independence better. Military men dominated Mexico's nineteenth-century history, most particularly General Antonio López de Santa Anna, under whom the Mexican military were defeated by Texas insurgents for independence in 1836 and then the U.S. invasion of Mexico (1846–48). With the overthrow of Santa Anna in 1855 and the installation of a government of political liberals, Mexico briefly had civilian heads of state. The Liberal Reforms that were instituted by Benito Juárez sought to curtail the power of the military and the church and wrote a new constitution in 1857 enshrining these principles. Conservatives comprised large landowners, the Catholic Church, and most of the regular army revolted against the Liberals, fighting a civil war. The Conservative military lost on the battlefield. But Conservatives sought another solution, supporting the French intervention in Mexico (1862–65). The Mexican army loyal to the liberal republic were unable to stop the French army's invasion, briefly halting it with a victory at Puebla on 5 May 1862. Mexican Conservatives supported the installation of Maximilian Hapsburg as Emperor of Mexico, propped up by the French and Mexican armies. With the military aid of the U.S. flowing to the republican government in exile of Juárez, the French withdrew its military supporting the monarchy and Maximilian was caught and executed. The Mexican army that emerged in the wake of the French Intervention was young and battle tested, not part of the military tradition dating to the colonial and early independence eras.
Liberal General Porfirio Díaz was part of the new Mexican military, a hero of the Mexican victory over the French on Cinco de Mayo 1862. He revolted against the civilian liberal government in 1876, and remained continuously in the presidency from 1880 to 1911. Over the course of his presidency, Díaz began professionalizing the army that had emerged. By the time he turned 80 years old in 1910, the Mexican military was an aging, largely ineffective fighting force. When revolts broke out in 1910–11 against his regime, a rebel forces scored decisive victories over the Federal Army in the opening chapter of the Mexican Revolution (1910–1920). Díaz resigned in May 1911, but Francisco I. Madero, on whose political behalf rebels rose against Díaz, demobilized the rebel forces and kept the Federal Army in place. "This single decision cost [Madero] the presidency and his life." Army General Victoriano Huerta seized the presidency of Madero in 1913, with Madero murdered in the coup d'état. Civil war broke out in the wake of the coup. Huerta's Federal Army racked up one defeat after another by the revolutionary armies, with Huerta resigning in 1914. The Federal Army ceased to exist. A new generation of fighting men, most of whom with no formal military training but were natural soldiers, now fought against each other in a civil war of the winners. The Constitutionalist Army under the civilian leadership of Venustiano Carranza and the military leadership of General Álvaro Obregón were the victors in 1915. The revolutionary military men were to continue to dominate Mexico's postrevolutionary period, but the military men who became presidents of Mexico brought the military under civilian control, systematically reining in the power of the military and professionalizing the force. The Mexican military has been under civilian government control with no President of Mexico being military generals since 1946. The fact of Mexico's civilian control of the military is in contrast the situation in many other countries in Latin America.
