Each May 5th, Cinco de Mayo celebrations are held in cities throughout the United States. But few people know the holiday's significance. It's a story that began on a sweltering morning, May 5, 1862, in the city of Puebla, Mexico and surrounding forts, when an ill-equipped Mexican Army, along with Zacapoaxtla Indians and regular citizens, beat the invading French Army. Filmed in Mexico and the US, this is the riveting story--from events leading up to the bloody battle and the aftermath. Today, the memory of French occupation has faded, except for Cinco de Mayo--the day the Mexicans defeated the most powerful army in the world.