The holiday actually commemorates the Mexican army’s victory over French forces at the Battle of Puebla on May 5, 1862.

Cinco de Mayo commemorates the Mexican army's victory over the Second French Empire, led by Napoleon III, at the Battle of Puebla on May 5, 1862, hence the name. The holiday is celebrated across the U.S. and in parts of Mexico, particularly in the City of Puebla, where the battle took place.