I know this is a bit late, but I had to post it! Well, for one thing, it is not about Mexican Independence! However, had this event not have occurred, the United States and Mexico might have a bit of a different outcome. So while you are sipping on your tequila, here are a few things to think about.
According to some sources on Wikipedia, the date is observed to commemorate the Mexican army's unlikely victory over French forces at the Battle of Puebla on May 5, 1862, under the leadership of General Ignacio Zaragoza Seguín. The actual event of Mexican Independence is on September 16th. Wow, that means it's two days before my birthday. How interesting, right? Had Mexico not won that particular battle, the United States might still have ended up a confederacy due to the fact that Napoleon was in a good relationship with the Confederacy and could supply weapons amongst other things. Mexico's battle resulted in France's forces weakened which allowed the Union Army to take advantage of the situation. Interesting news! Well, that about does it for the brief history. Take a little sip of Tequila and eat some good Mexican food! Authentic stuff! Enjoy!