Cinco de Mayo

From Wikipedia:

In 1861, in response to Mexico's refusal to pay off its debt, Britain, Spain & France sent troops to Mexico; they arrived in January of 1862. The new democratically-elected government of President Benito Juárez made agreements with the British & the Spanish, who promptly recalled their armies, but the French stayed, thus beginning the period of the French intervention in Mexico. Emperor Napoleon III wanted to secure French dominance in the former Spanish colony, including installing one of his relatives, Archduke Maximilian of Austria, as ruler of Mexico. Confident of a quick victory, 6,500 French soldiers marched on to Mexico City to seize the capital before the Mexicans could muster a viable defense. Along their march, the French already encountered stiff resistance before Zaragoza struck out to intercept the invaders.
The battle between the French & Mexican armies occurred on May 5th when Zaragoza's ill-equipped militia of 4,500 men encountered the better-armed French force. However, Zaragoza's small & nimble cavalry units were able to prevent French dragoons from taking the field & overwhelming the Mexican infantry. With the dragoons removed from the main attack, the Mexicans routed the remaining French soldiers with a combination of their tenacity, inhospitable terrain, & a stampede of cattle set off by local peasants. The invasion was stopped and crushed. Zaragoza won the battle but lost the war. The French Emperor, upon learning of the failed invasion, immediately dispatched another force, this time numbering 30,000 soldiers. By 1864, they succeeded in defeating the Mexican army & occupying Mexico City. Archduke Maximillian became Emperor of Mexico.
Maximilian's rule was short-lived. Mexican rebels opposed to his rule resisted, seeking the aid of the United States. Once the American Civil War was over, the U.S. military began supplying Mexicans with weapons & ammo, & by 1867, the rebels finally defeated the French & deposed their puppet Emperor. The Mexican people then reelected Juárez as president.
In the U.S., the "Batalla de Puebla" came to be known as simply "5 de Mayo" & many people wrongly equate it with Mexican Independence which was on September 16th, 1810, nearly a 50 year difference. Cinco de Mayo has become more of Chicano holiday than a Mexican one. Cinco de Mayo is celebrated on a much larger scale here in the U.S. than it is in Mexico. People of Mexican descent in the United States celebrate this significant day by having parades, mariachi music, folklorico dancing & other types of festive activities.