Cinco de mayo ("Fifth of May" in Spanish) is a national holiday in Mexico which commemorates the victory of Mexican forces led by General Ignacio Zaragoza over the French expeditionary forces in the Battle of Puebla on May 5, 1862.
Contrary to popular belief in the United States, Cinco de mayo is not considered the most important national holiday in Mexico. That distinction is reserved for Dieciséis de septiembre (September 16), which is celebrated from the eve of September 15 with a re-creation of the Grito de Dolores at all executive government branch offices' courts (from the President down to the municipal governments) and lasts through the night.
Celebration of the Cinco de mayo is most intense in the state and city of Puebla.
In the Southwest United States, Cinco de Mayo has become a somewhat important holiday celebrated by Mexican-Americans. Non-Mexican Americans also use the holiday as an excuse to party. Consumption of Tequila and Mexican beer increases on this day. The celebration of the day by non-Mexicans is similar to the celebration of St. Patrick's Day by non-Irish.