Mexican republicans United States (material support and volunteers)
Leonardo Márquez Miguel Miramón Tomás Mejía Camacho Napoléon III Élie Frédéric Forey Abel Douay François Achille Bazaine King Carlos V José Manuel Pareja Casto Méndez Núñez
President Benito Juárez Ignacio Zaragoza Porfirio Díaz† Ignacio Comonfort†
At least 80,000 46,000 35,000
At least 90,000
Casualties and Losses
9,000–15,000 6,284 2,799
The Mexican Civil War (Spanish: La Guerra Civil Mexicana) was a civil war fought in Mexico in the early 1860s. The war began as a result of outbreaks of violence between different political camps during the writing of the country's first constitution; Mexico had just achieved independence in a brief but violent war with the Kingdom of Spain. Monarchists, in favor of either an absolute or constitutional monarchy, faced a broad coalition of conservative, liberal, and radical republicans, and thus found their ability to coordinate and wage war much easier. The war was also a proxy war, as the Mexican monarchists were supported militarily and diplomatically by the French Empire, the Kingdom of Spain, and other European powers. Likewise, the Mexican republicans received supplies and volunteers (in smaller amounts) from the United States.
After securing independence in March 1861, Mexican governors, politicians, and generals that had fought for independence sought to organize a constitutional convention to form Mexico's first sovereign government. However, tensions were heightened when protesters in favor of a monarchy were arrested and, later, opened fire on by a local governor in Mexico City, who soon after declared martial law. After gun battles between republican and monarchists militias throughout late April, leading monarchist officials promulgated the Imperial Declaration of Government, a document declaring their intent to form a new Mexican Empire. As provisional emergency governments were formed and militias organized, French Emperor Napoléon III, intent on extending France's influence in the Americas, gathered his ally in Spain and organized a military expedition to support the Mexican monarchists. A fleet of coalition warships and over 80,000 troops landed in Veracruz in July 1861.
Several campaigns were fought in central and south Mexico throughout the war, in which the republicans held their own against the combined strength of the monarchists and their European allies. By autumn 1863, however, the tide had very clearly turned, and a final campaign in the north, in which coalition and monarchist troops chased the retreating and dwindling republican army through the desert, sealed the fate of the republican cause. The execution of Porfirio Díaz, the ranking republican general, and the flight of Benito Juárez officially ended the civil war. After months of apprehension and political debate, Ferdinand Maximilian Joseph, a member of the Habsburgs, was invited (and accepted) to take the crown of the Mexican Emperor.