Cinco de Mayo is an exciting festival. But there are plenty of myths around it as well. Here are 5 of those. Cinco de Mayo is not the celebration of Mexico’s independence from Spain – that anniversary happens in September. May 5th, 1862 is when Mexico defeated French colonizers in the battle at Puebla and told them to hit the road. In addition, he May holiday is not considered a national one in Mexico. It's only celebrated in several regions.