May 5th or Cinco de Mayo is not a national Mexican holiday, it is not Mexico’s Independence Day, and from what we have read, and for some reason or other, it is more celebrated in the U.S. than it is in Mexico--except in the city of Puebla.
On May 5, 1862 there was battle between some out numbered and untrained Mexican troops in a city named Puebla near Mexico City who repelled Napoleon’s massive army which he had sent to collect a debt that Mexico couldn’t pay. Remember that the French army was probably the best army in the world at the time. What is generally not known is that a successful invasion of Mexico by the French in 1862 may have led to a (planned) French alliance with the Southern states. That alliance would strengthen the South and help solidify the Civil War division between the North and South resulting in two countries which could have been Napoleon’s plan all along. Although not a major strategic win in the overall war, the success at Puebla represented a great symbolic victory for the Mexican government and bolstered the resistance movement.
Read more at: The Battle of Puebla and Cinco de Mayo
Wikipedia: Cinco de Mayo