
Contrary to widespread popular belief, Cinco de Mayo is not Mexico's Independence Day—the most important national patriotic holiday in Mexico—which is actually celebrated on September 16.
Cinco de Mayo celebrates the will and courage of the Mexican people to fight the French occupation in 1862. After the Mexican-American war, Mexico had an enormous debt to several nations and its treasury had no way of paying back. The French, aided by a few Mexican people who helped them, saw this as a good opportunity to gain territory in the Americas. One of the initial battles, which took place on May 5th, was the battle of Puebla, a town 100 miles from Mexico city. Here, the French Army was humiliated and defeated by the Mexican people who defended their city armed with a few weapons and household tools; Cinco de Mayo commemorates this battle.
Although the French continued to advance to Mexico and succeeded in installing Maximilian of Hapsburg as the new Emperor of Mexico (1864-1867), the battle of Puebla unified and inspired the people of Mexico to continue to fight the French until they were defeated. Benito Juarez, then president of Mexico at that time, fled Mexico City and from Northern Mexico and from the US directed the operations to fight the invaders and finally succeeded. Source: Gayle Brock YMCA of USA 2012