<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> <P> The Battle of Puebla was significant, both nationally and internationally, for several reasons . First, although considerably outnumbered, the Mexicans defeated a much - better - equipped French army . "This battle was significant in that the 4,000 Mexican soldiers were greatly outnumbered by the well - equipped French army of 8,000 that had not been defeated for almost 50 years ." Second, since the Battle of Puebla, some have argued that no country in the Americas has subsequently been invaded by any other European military force . Historian Justo Sierra has written in his Political Evolution of the Mexican People that, had Mexico not defeated the French in Puebla on May 5, 1862, France would have gone to the aid of the Confederacy in the U.S. Civil War and the United States' destiny would have been different . </P> <P> According to a paper published by the UCLA Center for the Study of Latino Health and Culture about the origin of the observance of Cinco de Mayo in the United States, the modern American focus on that day first started in California in 1863 in response to the resistance to French rule in Mexico . "Far up in the gold country town of Columbia (now Columbia State Park) Mexican miners were so overjoyed at the news that they spontaneously fired off rifle shots and fireworks, sang patriotic songs and made impromptu speeches ." </P> <P> A 2007 UCLA Newsroom article notes that, "the holiday, which has been celebrated in California continuously since 1863, is virtually ignored in Mexico ." TIME magazine reports that "Cinco de Mayo started to come into vogue in 1940s America during the rise of the Chicano Movement ." The holiday crossed over from California into the rest of the United States in the 1950s and 1960s but did not gain popularity until the 1980s when marketers, especially beer companies, capitalized on the celebratory nature of the day and began to promote it . It grew in popularity and evolved into a celebration of Mexican culture and heritage, first in areas with large Mexican - American populations, like Los Angeles, Chicago, Houston and San Jose . </P>

When did they start celebrating cinco de mayo