<P> Cinco de Mayo is sometimes mistaken for Mexico's Independence Day--the most important national holiday in Mexico--which is celebrated on September 16, commemorating the Cry of Dolores that initiated the war of Mexican independence from Spain . </P> <P> Cinco de Mayo has its roots in the Second French intervention in Mexico, which took place in the aftermath of the 1846--48 Mexican--American War and the 1858--61 Reform War . The Reform War was a civil war that pitted Liberals (who believed in separation of church and state, and freedom of religion) against Conservatives (who favored a tight bond between the Catholic Church and the Mexican state). These wars nearly bankrupted the Mexican Treasury . On July 17, 1861, Mexican President Benito Juárez issued a moratorium in which all foreign debt payments would be suspended for two years . In response, Britain, France, and Spain sent naval forces to Veracruz to demand reimbursement . Britain and Spain negotiated with Mexico and withdrew, but France, at the time ruled by Napoleon III, decided to use the opportunity to establish an empire in Mexico that would favor French interests, the Second Mexican Empire . The empire was part of an envisioned "Latin America" (term used to imply cultural kinship of the region with France) that would rebuild French influence in the American continent and exclude Anglophone American territories . </P> <P> Late in 1861, a well - armed French fleet stormed Veracruz, landing a large French force and driving President Juárez and his government into retreat . Moving on from Veracruz towards Mexico City, the French army encountered heavy resistance from the Mexicans close to Puebla, at the Mexican forts of Loreto and Guadalupe . The French army of 8,000 attacked the poorly equipped Mexican army of 4,000 . On May 5, 1862, the Mexicans decisively defeated the French army . The victory represented a significant morale boost to the Mexican army and the Mexican people at large and helped establish a sense of national unity and patriotism . </P> <P> The Mexican victory, however, was short - lived . A year later, with 30,000 troops, the French were able to defeat the Mexican army, capture Mexico City, and install Emperor Maximilian I as ruler of Mexico . The French victory was itself short - lived, lasting only three years, from 1864 to 1867 . By 1865, "with the American Civil War now over, the U.S. began to provide more political and military assistance to Mexico to expel the French". Upon the conclusion of the American Civil War, Napoleon III, facing a persistent Mexican guerilla resistance, the threat of war with Prussia, and "the prospect of a serious scrap with the United States", retreated from Mexico starting in 1866 . The Mexicans recaptured Mexico City, and Maximilian I was apprehended and executed, along with his Mexican generals Miguel Miramón and Tomás Mejía Camacho in Cerro de las Campanas, Querétaro . "On June 5, 1867, Benito Juárez finally entered Mexico City where he installed a new government and reorganized his administration ." </P>

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