It's funny that only Mexicans living in the United States celebrate the 5th of May, in Mexico proper is not even a holiday and nobody celebrates it.
For all of you that don't know what's the big deal about the 5th of May it was the day that a smaller, ill-armed Mexican army defeated Napoleo's III bigger and better French army, believe it or not that battle decided the fate United States history too, for if the Fench had won that battle, France would had been able to help and funnel arms to the Confederate army which was fighting a war against the North. The Mexicans prevented France from setting up a beachhead and bringing it tens of thousands of seasoned fighters that were going to be sent to help the South's rebel army.