The holiday of Cinco De Mayo, The Fifth Of May, commemorates the victory of the Mexicans over the French army at The Battle Of Puebla in 1862. It is primarily a regional holiday celebrated in the Mexican state capital city of Puebla and throughout the state of Puebla, but is also celebrated in other parts of the country and in U.S.cities with a significant Mexican population. It is not, as many people think, Mexico's Independence Day, which is actually September 16.