'5 de Mayo parade in Alpine' photo (c) 2010, Matthew Rutledge - license: https://creativecommons.org/licenses/by/2.0/

Cinco de Mayo, May 5th, commemorates the defeat of the French by the Mexican Army in 1862. It’s a holiday celebrated in parts of Mexico, and is celebrated by Mexican immigrants and Mexican-Americans in the United States.

You might be interested in The Best Sites For Teaching & Learning About Cinco de Mayo.