I've always had a special place in my heart for Hispanic holidays. I have had Spanish class since kindergarten (that's 12 years of Spanish!) and every year we would celebrate Cinco de Mayo, Three Kings, Dia de los Muertos, and Marde Gras. These holidays - they're so festive and fun, with beautiful dresses and dances, costumes, and delicious food.
Cinco de Mayo is a Mexican holiday (just Puebla) which celebrates the Mexican army's amazing defeat of the French. They were huge underdogs at this battle (The battle of Puebla). First, they were outnumbered 2:1; second, they equipment they were using was subpar and could not compare to the weapons of France. Normally Cinco de Mayo is confused with Mexican Independence Day (September 16th).
In the United States, Cinco de Mayo is a celebration of Mexican heritage (similar to St.Patrick's Day for the Irish) observed by all.