Cinco de Mayo marks a Mexican win over Napoleon III's invading army
In 1862 France invaded Mexico, officially to collect unpaid debts, really to install a European monarch and check American power. A Mexican victory at Puebla on 5 May stalled the march for a year, and five years later the emperor France had imported faced a firing squad.
The trigger came in July 1861, when President Benito Juárez, fresh from winning the Reform War against Mexico's conservatives, suspended payments on foreign debt and expelled Spanish diplomats. Spain, France and a hesitant Britain signed the Convention of London to force repayment. Spanish troops from Cuba seized Veracruz that December, and French and British contingents joined them in January 1862, while the Spanish general Juan Prim publicly denied any plan to conquer or change the government.
The alliance fell apart at Orizaba in April 1862 once France made plain it meant to invade and interfere. Britain and Spain withdrew after securing a share of Veracruz customs revenue for creditors, leaving France alone. Napoleon III had been courted by Mexican monarchist exiles through his Spanish wife, Eugénie, and the American Civil War gave him an opening: the United States was too busy to object. He spoke of free trade and access to Mexican silver, but a French-dependent Mexico was also meant to curb Washington's influence across Latin America. Defeated Mexican conservatives, the Church and much of the elite welcomed the plan.
About 6,500 French soldiers marched inland. At Puebla on 5 May 1862, some 5,000 Mexicans under Ignacio Zaragoza and Porfirio Díaz held the heights of Cerro de Guadalupe against 6,000 French troops, inflicting 476 casualties for 227 of their own. The win strengthened Juárez and rallied national feeling, though French and imperial forces went on to take most major cities and crown Archduke Maximilian. He turned out to lean liberal, keeping some of Juárez's reforms, while republican guerrillas fought on and Juárez never left Mexican soil.
The tide turned after the Confederacy surrendered in 1865. The reunited United States, which had never stopped recognising Juárez, invoked the Monroe Doctrine and sent material aid. With Prussia threatening France's own borders and discontent rising at home, Napoleon began pulling troops out in 1866. The Second Mexican Empire collapsed, and on 19 June 1867 a firing squad shot Maximilian alongside two conservative commanders, Miguel Miramón and Tomás Mejía.
Source: Second French intervention in Mexico
