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.